The plant-signaling molecules salicylic acid ( SA ) and jasmonic acid ( JA ) play an important role in induced disease resistance pathways .

Cross-talk between SA- and JA-dependent pathways can result in inhibition of JA-mediated defense responses .

We investigated possible antagonistic interactions between the SA-dependent systemic acquired resistance ( SAR ) pathway , which is induced upon pathogen infection , and the JA-dependent induced systemic resistance ( ISR ) pathway , which is triggered by nonpathogenic Pseudomonas rhizobacteria .

In Arabidopsis thaliana , SAR and ISR are effective against a broad spectrum of pathogens , including the foliar pathogen Pseudomonas syringae pv . tomato ( Pst ) .

Simultaneous activation of SAR and ISR resulted in an additive effect on the level of induced protection against Pst .

In Arabidopsis genotypes that are blocked in either SAR or ISR , this additive effect was not evident .

Moreover , induction of ISR did not affect the expression of the SAR marker gene PR-1 in plants expressing SAR .

Together , these observations demonstrate that the SAR and the ISR pathway are compatible and that there is no significant cross-talk between these pathways .

SAR and ISR both require the key regulatory protein NPR1 .

Plants expressing both types of induced resistance did not show elevated Npr1 transcript levels , indicating that the constitutive level of NPR1 is sufficient to facilitate simultaneous expression of SAR and ISR .

These results suggest that the enhanced level of protection is established through parallel activation of complementary , NPR1-dependent defense responses that are both active against Pst .

Therefore , combining SAR and ISR provides an attractive tool for the improvement of disease control .


High-frequency bud break and multiple shoots were induced in apical shoot buds and nodal explants ofMorus cathayana , M. lhou andM. serrata on Murashige and Skoog ( MS ) medium containing 0.5 - 1.0 mg/l 6-benzylaminopurine ( BAP ) .

Addition of gibberellic acid ( 0.4 mg/l ) along with BAP induced faster bud break both in apical shoot buds and nodal explants and also enhanced the frequency of bud break in all three species .

Shoot culture initiation was greatly influenced by explant type , explant age and explanting season .

The shoots were successfully rooted on half-strength MS medium containing a combination of indole-3-acetic acid , indole-3-butyric acid and indole-3-propionic acid , each at 1.0 mg/l .

The plantlets were successfully acclimated and eventually established in soil .


In tobacco ( Nicotiana tabacum ) , nicotine is the predominant alkaloid .

It is produced in the roots and accumulated mainly in the leaves .

Jasmonates play a central signaling role in damage-induced nicotine formation .

The genome sequence of tobacco provides us an almost complete inventory of structural and regulatory genes involved in nicotine pathway .

Phylogenetic and expression analyses revealed a series of structural genes of the nicotine pathway , forming a regulon , under the control of jasmonate-responsive ETHYLENE RESPONSE FACTOR ( ERF ) transcription factors .

The duplication of NAD and polyamine metabolic pathways and the subsequent recruitment of duplicated primary metabolic genes into the nicotine biosynthesis regulon were suggested to be the drivers for pyridine and pyrrolidine ring formation steps early in the pathway .

Transcriptional regulation by ERF and cooperatively acting MYC2 transcription factors are corroborated by the frequent occurrence of cognate cis-regulatory elements of the factors in the promoter regions of the downstream structural genes .

The allotetraploid tobacco has homologous clusters of ERF genes on different chromosomes , which are possibly derived from two ancestral diploids and include either nicotine-controlling ERF189 or ERF199 A large chromosomal deletion was found within one allele of the nicotine-controlling NICOTINE2 locus , which is part of one of the ERF gene clusters , and which has been used to breed tobacco cultivars with a low-nicotine content .


A novel method based on off-line membrane-supported liquid-liquid-liquid microextraction ( MS-LLLME ) combined with on-column anion-selective exhaustive injection ( ASEI ) capillary electrophoresis-ultraviolet ( CE-UV ) detection was established for the analysis of seven phytohormones ( abscisic acid ( ABA ) , jasmonic acid ( JA ) , 2,4-dichlorophenoxyacetic acid ( 2,4-D ) , 1-naphthalene acetic acid ( NAA ) , indole-3-acetic acid ( IAA ) , salicylic acid ( SA ) and gibberellic acid ( GA ) ) .

In MS-LLLME , the target phytohormones were extracted from the acid donor phase to the alkaline acceptor phase , and the acceptor solutions were directly analyzed by ASEI-CE-UV .

Under the optimal experimental conditions , the analytical performance of the method was evaluated .

The limits of detection ( LODs ) of ABA , JA , 2,4-D , NAA , IAA , SA and GA were determined to be 1.00 , 2.21 , 0.33 , 0.17 , 0.67 , 0.05 and 16.5ng/mL , respectively .

The relative standard deviations ( RSDs , n=7 ) ranged from 4.7 % to 12.9 % , and the enrichment factors were in the range of 307 to 20,160 .

The proposed method was successfully applied for the determination of multiple phytohormones in banana , cabbage and cucumber extracts , and ABA , IAA and SA were detected in these samples .

The recoveries for the spiked samples were in the range of 79.0 to 116.4 % .

The proposed method was demonstrated to be suitable for the simultaneous quantification of multiple phytohormones with high sensitivity and good sample cleanup ability .


The ability to adjust growth and development to the availability of mineral nutrients in the soil is an essential life skill of plants but the underlying signaling pathways are poorly understood .

In Arabidopsis thaliana , shortage of potassium ( K ) induces a number of genes related to the phytohormone jasmonic acid ( JA ) .

Using comparative microarray analysis of wild-type and coi1 - 16 mutant plants , we classified transcriptional responses to K with respect to their dependence on COI1 , a central component of oxylipin signaling .

Expression profiles obtained in a short-term experiment clearly distinguished between COI1-dependent and COI1-independent K-responsive genes , and identified both known and novel targets of JA-COI1-signaling .

During long-term K-deficiency , coi-16 mutants displayed de novo responses covering similar functions as COI1-targets except for defense .

A putative role of JA for enhancing the defense potential of K-deficient plants was further supported by the observation that plants grown on low K were less damaged by thrips than plants grown with sufficient K.


The Arabidopsis Jasmonate ZIM-domain proteins ( JAZs ) act as substrates of SCF(COI1 ) complex to repress their downstream targets , which are essential for JA-regulated plant development and defense .

The bHLH transcription factor MYC2 was found to interact with JAZs and mediate JA responses including JA-inhibitory root growth .

Here , we identified another bHLH transcription factor MYC3 which directly interacted with JAZs by virtue of its N-terminal region to regulate JA responses .

The transgenic plants with overexpression of MYC3 exhibited hypersensitivity in JA-inhibitory root elongation and seedling development .

The JAZ-interacting pattern and the JA-induced expression pattern of MYC3 were distinguishable from those of MYC2 .

We speculate that MYC3 and MYC2 may have redundant but also distinguishable functions in regulation of JA responses .


Health effects of subacute treatment of combinations of gibberellic acid and ethephon ( 2-chloroethylphosphonic acid ) were investigated .

Mice was used as an experimental model .

Ten groups of male ICR ( CD-1 ) mice were treated with oral doses of 25 , 50 and 100 mg of either gibberellic acid ( GA3 ) , ethephon ( 2-chloroethylphosphonic acid ) alone or in combination / kg body weight for 11 weeks .

A significant dose dependent reduction in weight gain and low dry matter intakes were recorded in animals treated with the combination of both chemicals .

Treated groups showed statistically significant increases in mean liver , kidney and spleen weights .

Hemoglobin ( Hb ) and total erythrocyte count ( TEC ) decreased while total leukocyte count ( TLC ) was raised in all treated groups .

Gibberellic acid ( alone ) treated animals showed the highest activity of liver aspartate aminotransferase ( AST ) while no significant variations were recorded among other groups .

No significant differences were recorded in the activity of hepatic alanine aminotransferase ( ALT ) .

A highly significant variation was recorded among the three treatments in serum urea level .

No significant difference was noted among the three treatments in serum creatinine .

All treatments caused significant dose dependent increases in creatinine than that of the control group .

A highly significant dose dependent variation occurred in acetyl choline esterase ( AChE ) activity among treated groups .

Groups treated with ethephon alone showed the greatest inhibition in brain AChE.


The cytokinin activity has been isolated and identified from extracts of immature mango ( Mangifera indica L. ) seeds .

The structures of zeatin , zeatin riboside , and N(6)-(Delta(2)-isopentenyl)adenine riboside were confirmed on the basis of their chromatographic behavior and mass spectra of trimethylsilyl derivatives .

Both trans and cis isomers of zeatin and zeatin riboside were also identified by the retention times of high performance liquid chromatography .

In addition , an unidentified compound appeared to be a cytokinin glucoside .

The concentration of cytokinins in the panicle and pulp of mango reached a maximum 5 to 10 days after full bloom and decreased rapidly thereafter .

The cytokinin level in the seed remained high until the 28th day after full bloom .

The quantity of cytokinins in pulp per fruit increased from the 10th day after full bloom , the maximum being attained around the 50th day after full bloom .

Similarly , the amount of cytokinins per seed increased from the 10th day after full bloom , reaching a peak on the 40th day and decreasing gradually thereafter .

A high percentage of fruit set in mango was persistently maintained by supplying 6-benzylaminopurine ( 1.5 x 10(3 ) micromolar ) onto the panicle at the anthesis stage and by supplying gibberellic acid ( 7.2 x 10(2 ) micromolar ) and naphthalene acetamide ( 3.1 x 10 micromolar ) at the young fruit stage .


Gibberellin ( GA ) , a diterpene hormone , plays diverse roles in plant growth and development , including seed germination , stem elongation , and flowering time . Although it is known that GA accelerates flowering through degradation of transcription repressors , DELLAs , the underlying mechanism is poorly understood .

We show here that DELLA directly binds to microRNA156 (miR156)-targeted SQUAMOSA PROMOTER BINDING-LIKE ( SPL ) transcription factors , which promote flowering by activating miR172 and MADS box genes .

The interaction between DELLA and SPL interferes with SPL transcriptional activity and consequently delays floral transition through inactivating miR172 in leaves and MADS box genes at shoot apex under long-day conditions or through repressing MADS box genes at the shoot apex under short-day conditions .

Our results elucidate the molecular mechanism by which GA controls flowering and provide the missing link between DELLA and MADS box genes .


Gibberellic acid ( GA(3 ) ) promotes and continuous gold light inhibits germination of seeds of a dwarf strain ( WB-2 ) of watermelon [ Citrullus lanatus ( Thunb . ) Matsu . and Nakai ] .

Osmotic inhibition of germination with mannitol in light-grown seeds of WB-2 was only slightly reversed by GA(3 ) at the concentrations used , whereas , GA(3 ) substantially relieved osmotic inhibition in dark-grown seeds .

The effects of GA(3 ) and gold light on development of catalase and invertase activities and on levels of free amino acids in germinating seeds of WB-2 were examined .

Light depressed development of catalase and invertase activity .

Levels of free amino acids increased more slowly in embryonic axes of light- than dark-incubated seeds , but in cotyledons higher levels of amino acids were maintained in light-grown seeds .

GA(3 ) accelerated the development of catalase activity in whole embryos and invertase activity in embryonic axes , but did not significantly affect invertase activity in cotyledons during germination .

GA(3 ) had little effect on amino acid pools in cotyledons and embryonic axes .


Plant growth and development are controlled by nine structurally distinct small molecules termed phytohormones .

Over the last 20 years , the molecular basis of their signal transduction , from receptors to transcription factors , has been dissected using mainly Arabidopsis thaliana and rice as model systems .

Phytohormones can be broadly classified into two distinct groups on the basis of whether the subcellular localization of their receptors is in the cytoplasm or nucleus , and hence soluble , or membrane-bound , and hence insoluble .

Soluble receptors , which control the responses to auxin , jasmonates , gibberellins , strigolactones and salicylic acid , signal either directly or indirectly via the destruction of regulatory proteins .

Responses to abscisic acid are primarily mediated by soluble receptors that indirectly regulate the phosphorylation of targeted proteins .

Insoluble receptors , which control the responses to cytokinins , brassinosteroids and ethylene , transduce their signal through protein phosphorylation .

This chapter provides a comparison of the different components of these signalling systems , and discusses the similarities and differences between them .


High temperature ( HT ) , high humidity ( HH ) , and pathogen infection often co-occur and negatively affect plant growth .

However , these stress factors and plant responses are generally studied in isolation .

The mechanisms of synergistic responses to combined stresses are poorly understood .

We isolated the subgroup IIb WRKY family member CaWRKY6 from Capsicum annuum and performed quantitative real-time PCR analysis .

CaWRKY6 expression was upregulated by individual or simultaneous treatment with HT , HH , combined HT and HH ( HTHH ) , and Ralstonia solanacearum inoculation , and responded to exogenous application of jasmonic acid ( JA ) , ethephon , and abscisic acid ( ABA ) .

Virus-induced gene silencing of CaWRKY6 enhanced pepper plant susceptibility to R. solanacearum and HTHH , and downregulated the hypersensitive response ( HR ) , JA- , ethylene (ET)- , and ABA-induced marker gene expression , and thermotolerance-associated expression of CaHSP24 , ER-small CaSHP , and Chl-small CaHSP .

CaWRKY6 overexpression in pepper attenuated the HTHH-induced suppression of resistance to R. solanacearum infection .

CaWRKY6 bound to and activated the CaWRKY40 promoter in planta , which is a pepper WRKY that regulates heat-stress tolerance and R. solanacearum resistance .

CaWRKY40 silencing significantly blocked HR-induced cell death and reduced transcriptional expression of CaWRKY40 .

These data suggest that CaWRKY6 is a positive regulator of R. solanacearum resistance and heat-stress tolerance , which occurs in part by activating CaWRKY40 .


Jasmonates are essential engineers of plant defense responses against many pests , including herbivorous insects .

Herbivory induces the production of jasmonic acid ( JA ) and its bioactive conjugate jasmonoyl-L-isoleucine ( JA-Ile ) , which then triggers a large transcriptional reprogramming to promote plant acclimation .

The contribution of the JA pathway , including its components and regulators , to defense responses against insect herbivory can be evaluated by conducting bioassays with a wide range of host plants and insect pests .

Here , we describe a detailed and reproducible protocol for testing feeding behavior of the generalist herbivore Spodoptera littoralis on the model plant Arabidopsis thaliana and hence infer the contribution of JA-mediated plant defense responses to a chewing insect .


In nature , herbivorous insects and plant pathogens are generally abundant when plants are flowering .

Thus , plants face a diversity of attackers during their reproductive phase .

Plant responses to one attacker can interfere with responses to a second attacker , and phytohormones that orchestrate plant reproduction are also involved in resistance to insect and pathogen attack .

We quantified phytohormonal responses of flowering plants exposed to single or dual attack and studied resistance mechanisms of plants in the flowering stage .

Flowering Brassica nigra were exposed to either a chewing caterpillar , a phloem-feeding aphid or a bacterial pathogen , and plant hormonal responses were compared with dual attack situations .

We quantified phytohormones in inflorescences and leaves , and determined the consequences of hormonal changes for components of direct and indirect plant resistance .

Caterpillars were the main inducers of jasmonates in inflorescences , and the phytohormonal profile of leaves was not affected by either insect or pathogen attack .

Dual attack increased plant resistance to caterpillars , but compromised resistance to aphids .

Parasitoid performance was negatively correlated with the performance of their hosts .

We conclude that plants prioritize resistance of reproductive tissues over vegetative tissues , and that a chewing herbivore species is the main driver of responses in flowering B. nigra .


During a compatible interaction , the sebacinoid root-associated fungi Piriformospora indica and Sebacina vermifera induce modification of root morphology and enhance shoot growth in Arabidopsis thaliana .

The genomic traits common in these two fungi were investigated and compared with those of other root-associated fungi and saprotrophs .

The transcriptional responses of the two sebacinoid fungi and of Arabidopsis roots to colonization at three different symbiotic stages were analyzed by custom-designed microarrays .

We identified key genomic features characteristic of sebacinoid fungi , such as expansions for gene families involved in hydrolytic activities , carbohydrate-binding and protein-protein interaction .

Additionally , we show that colonization of Arabidopsis correlates with the induction of salicylic acid catabolism and accumulation of jasmonate and glucosinolates ( GSLs ) .

Genes involved in root developmental processes were specifically induced by S. vermifera at later stages during interaction .

Using different Arabidopsis indole-GSLs mutants and measurement of secondary metabolites , we demonstrate the importance of the indolic glucosinolate pathway in the growth restriction of P. indica and S. vermifera and we identify indole-phytoalexins and specifically indole-carboxylic acids derivatives as potential key players in the maintenance of a mutualistic interaction with root endophytes .


We conducted a study of the patterns and dynamics of oxidized fatty acid derivatives ( oxylipins ) in potato leaves infected with the late-blight pathogen Phytophthora infestans .

Two 18-carbon divinyl ether fatty acids , colneleic acid and colnelenic acid , accumulated during disease development .

To date , there are no reports that such compounds have been detected in higher plants .

The divinyl ether fatty acids accumulate more rapidly in potato cultivar Matilda ( a cultivar with increased resistance to late blight ) than in cultivar Bintje , a susceptible cultivar .

Colnelenic acid reached levels of up to approximately 24 nmol ( 7 microgram ) per g fresh weight of tissue in infected leaves .

By contrast , levels of members of the jasmonic acid family did not change significantly during pathogenesis .

The divinyl ethers also accumulated during the incompatible interaction of tobacco with tobacco mosaic virus .

Colneleic and colnelenic acids were found to be inhibitory to P. infestans , suggesting a function in plant defense for divinyl ethers , which are unstable compounds rarely encountered in biological systems .


Petal color , size , and morphology play important roles in protecting other floral organs , attracting pollinators , and facilitating sexual reproduction in plants .

In a previous study , we obtained a petal degeneration mutant ( pdm ) from the ' FT ' doubled haploid line of Chinese cabbage and found that the candidate gene for pdm , Bra040093 , encodes the enzyme acyl-CoA oxidase1 .

In this study , we sought to examine the gene networks regulating petal development in pdm plants .

We show that the mRNA and protein expression of Bra040093 , which is involved in the jasmonic acid ( JA ) biosynthetic pathway , were significantly lower in the petals of pdm plants than in those of ' FT ' plants .

Similarly , the JA and methyl jasmonate ( MeJA ) contents of petals were significantly lower in pdm plants than in ' FT ' plants and we found that exogenous application of these hormones to the inflorescences of pdm plants restored the ' FT ' phenotype .

Comparative analyses of the transcriptomes of ' FT ' , pdm and pdm + JA ( pJA ) plants revealed 10,160 differentially expressed genes ( DEGs ) with consistent expression tendencies in ' FT ' vs. pdm and pJA vs. pdm comparisons .

Among these DEGs , we identified 69 DEGs related to floral organ development , 11 of which are involved in petal development regulated by JA .

On the basis of qRT-PCR verification , we propose regulatory pathways whereby JA may mediate petal development in the pdm mutant .

We demonstrate that mutation of Bra040093 in pdm plants leads to reduced JA levels and that this in turn promotes changes in the expression of genes that are expressed in response to JA , ultimately resulting in petal degeneration .

These findings thus indicate that JA is associated with petal development in Chinese cabbage .

These results enhance our knowledge on the molecular mechanisms underlying petal development and lay the foundations for further elucidation of the mechanisms associated with floral organ development in Chinese cabbage .


BACKGROUND AND AIMS : Selected beneficial Pseudomonas spp . strains have the ability to influence root architecture in Arabidopsis thaliana by inhibiting primary root elongation and promoting lateral root and root hair formation .

A crucial role for auxin in this long-term ( 1week ) , long-distance plant-microbe interaction has been demonstrated .

METHODS : Arabidopsis seedlings were cultivated in vitro on vertical plates and inoculated with pathogenic strains Pseudomonas syringae pv . maculicola ( Psm ) and P. syringae pv . tomato DC3000 ( Pst ) , as well as Agrobacterium tumefaciens ( Atu ) and Escherichia coli ( Eco ) .

Root hair lengths were measured after 24 and 48h of direct exposure to each bacterial strain .

Several Arabidopsis mutants with impaired responses to pathogens , impaired ethylene perception and defects in the exocyst vesicle tethering complex that is involved in secretion were also analysed .

KEY RESULTS : Arabidopsis seedling roots infected with Psm or Pst responded similarly to when infected with plant growth-promoting rhizobacteria ; root hair growth was stimulated and primary root growth was inhibited .

Other plant- and soil-adapted bacteria induced similar root hair responses .

The most compromised root hair growth stimulation response was found for the knockout mutants exo70A1 and ein2 .

The single immune pathways dependent on salicylic acid , jasmonic acid and PAD4 are not directly involved in root hair growth stimulation ; however , in the mutual cross-talk with ethylene , they indirectly modify the extent of the stimulation of root hair growth .

The Flg22 peptide does not initiate root hair stimulation as intact bacteria do , but pretreatment with Flg22 prior to Psm inoculation abolished root hair growth stimulation in an FLS2 receptor kinase-dependent manner .

These early response phenomena are not associated with changes in auxin levels , as monitored with the pDR5::GUS auxin reporter .

CONCLUSIONS : Early stimulation of root hair growth is an effect of an unidentified component of living plant pathogenic bacteria .

The root hair growth response is triggered in the range of hours after bacterial contact with roots and can be modulated by FLS2 signalling .

Bacterial stimulation of root hair growth requires functional ethylene signalling and an efficient exocyst-dependent secretory machinery .


Tritrophic interactions involving a biocontrol agent , a pathogen , and a plant have been analyzed predominantly from the perspective of the biocontrol agent .

To explore the adaptive strategies of wheat in response to beneficial , pathogenic , and combined microorganisms , we performed the first comprehensive transcriptomic , proteomic , and biochemical analysis in wheat roots after exposure to Bacillus velezensis CC09 , Gaeumannomyces graminis var . tritici , and their combined colonization , respectively .

The transcriptional or translational programming of wheat roots inoculated with beneficial B. velezensis showed mild alterations compared with that of pathogenic G. graminis var . tritici .

However , the combination of B. velezensis and G. graminis var . tritici activated a larger transcriptional or translational program than for each single microorganism , although the gene expression pattern was similar to that of individual infection by G. graminis var . tritici , suggesting a prioritization of defense against G. graminis var . tritici infection .

Surprisingly , pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity made wheat pretreated with B. velezensis more sensitive to subsequent G. graminis var . tritici infection .

Additionally , B. velezensis triggered a salicylic acid (SA)-dependent mode of induced systemic resistance that resembles pathogen-induced systemic acquired resistance .

Wheat plants mainly depend on SA-mediated resistance , and not that mediated by jasmonic acid ( JA ) , against the necrotrophic pathogen G. graminis var . tritici .

Moreover , SA-JA interactions resulted in antagonistic effects regardless of the type of microorganisms in wheat .

Further enhancement of SA-dependent defense responses such as lignification to the combined infection was shown to reduce the level of induced JA-dependent defense against subsequent infection with G. graminis var . tritici .

Altogether , our results demonstrate how the hexaploid monocot wheat responds to beneficial or pathogenic microorganisms and prolongs the onset of take-all disease through modulation of cell reprogramming and signaling events .


Seed dormancy and germination in higher plants are partially controlled by the plant hormones abscisic acid ( ABA ) and gibberellic acid ( GA ) .

ABA establishes dormancy during embryo maturation , whereas GA breaks dormancy and induces germination .

Previous attempts to identify GA response genes were confounded because GA mutants are not expected to germinate and , unlike GA auxotrophs , should fail to be rescued by exogenous GA .

Here , we describe a screen for suppressors of the ABA-insensitive mutant ABI1 - 1 that enriches for GA auxotrophs and GA-insensitive mutants .

The vast majority ( 76 % ) of the suppressors of ABI1 - 1 strongly resemble GA auxotrophs in that they are severely dwarfed and have dark green foliage and flowers with underdeveloped petals and stamen .

Three isolates were alleles of the GA auxotroph ga1 .

The remaining severe dwarves were not rescued by GA and belong to a single complementation group that we designate sly1 ( Sleepy 1 ) .

The alleles of sly1 identified are the first recessive GA-insensitive mutations to reflect the full spectrum of GA-associated phenotypes , including the failure to germinate in the absence of the ABI1 - 1 lesion .

Thus , we postulate that SLY1 is a key factor in GA reception .


The formation of amylase isozymes in germinating rice ( Oryza sativa ) seeds was studied by isoelectric focusing on polyacrylamide gel disc electrophoresis .

Time sequence comparisons of the amylase zymogram were made between extracts from gibberellic acid-treated embryoless and embryo-attached half-endosperm of rice seeds .

In both cases , 4 major and 9 to 10 minor isozyme bands were detectable at the maximal stage of the enzyme induction .

However , in the embryo-attached half-seeds , bands started to diminish after the 5th day of incubation , in agreement with the results of time sequence analyses of enzyme activities .

Nearly identical patterns of amylase isozyme bands on a polyacrylamide gel disc electrophoresis in combination with isoelectric focusing indicate the intrinsic role of gibberellic acid in the starch breakdown in germinating rice seeds .

We tentatively assign the newly synthesized enzymes to be alpha-amylases based on experimental results concerning the lability of the preparation on a prolonged treatment at pH 3.3 and the stability on heat treatment for 15 minutes at 70 C.


Plants are continually exposed to pathogen attack but usually remain healthy because they can activate defences upon perception of microbes .

However , pathogens have evolved to overcome plant immunity by delivering effectors into the plant cell to attenuate defence , resulting in disease .

Recent studies suggest that some effectors may manipulate host transcription , but the specific mechanisms by which such effectors promote susceptibility remain unclear .

We study the oomycete downy mildew pathogen of Arabidopsis , Hyaloperonospora arabidopsidis ( Hpa ) , and show here that the nuclear-localized effector HaRxL44 interacts with Mediator subunit 19a ( MED19a ) , resulting in the degradation of MED19a in a proteasome-dependent manner .

The Mediator complex of ∼25 proteins is broadly conserved in eukaryotes and mediates the interaction between transcriptional regulators and RNA polymerase II .

We found MED19a to be a positive regulator of immunity against Hpa .

Expression profiling experiments reveal transcriptional changes resembling jasmonic acid/ethylene ( JA/ET ) signalling in the presence of HaRxL44 , and also 3 d after infection with Hpa .

Elevated JA/ET signalling is associated with a decrease in salicylic acid (SA)-triggered immunity ( SATI ) in Arabidopsis plants expressing HaRxL44 and in med19a loss-of-function mutants , whereas SATI is elevated in plants overexpressing MED19a .

Using a PR1::GUS reporter , we discovered that Hpa suppresses PR1 expression specifically in cells containing haustoria , into which RxLR effectors are delivered , but not in nonhaustoriated adjacent cells , which show high PR1::GUS expression levels .

Thus , HaRxL44 interferes with Mediator function by degrading MED19 , shifting the balance of defence transcription from SA-responsive defence to JA/ET-signalling , and enhancing susceptibility to biotrophs by attenuating SA-dependent gene expression .


Plants are the primary producers in most terrestrial ecosystems and have complex defense systems to protect their produce .

Defense-deficient , high-yielding agricultural monocultures attract abundant nonhuman consumers , but are alternatively defended through pesticide application and genetic engineering to produce insecticidal proteins such as Cry1Ac ( Bacillus thuringiensis ) .

These approaches alter the balance between yield protection and maximization but have been poorly contextualized to known yield-defense trade-offs in wild plants .

The native plant Nicotiana attenuata was used to compare yield benefits of plants transformed to be defenseless to those with a full suite of naturally evolved defenses , or additionally transformed to ectopically produce Cry1Ac .

An insecticide treatment allowed us to examine yield under different herbivore loads in N. attenuata 's native habitat .

Cry1Ac , herbivore damage , and growth parameters were monitored throughout the season .

Biomass and reproductive correlates were measured at season end .

Non-Cry1Ac-targeted herbivores dominated on noninsecticide-treated plants , and increased the yield drag of Cry1Ac-producing plants in comparison with endogenously defended or undefended plants .

Insecticide-sprayed Cry1Ac-producing plants lagged less in stalk height , shoot biomass , and flower production .

In direct comparison with the endogenous defenses of a native plant , Cry1Ac production did not provide yield benefits for plants under observed herbivore loads in a field study .


Rice OsEDR1 is a sequence ortholog of Arabidopsis EDR1 .

However , its molecular function is unknown .

We show here that OsEDR1-suppressing/knockout ( KO ) plants , which developed spontaneous lesions on the leaves , have enhanced resistance to Xanthomonas oryzae pv . oryzae ( Xoo ) causing bacterial blight disease .

This resistance was associated with increased accumulation of salicylic acid ( SA ) and jasmonic acid ( JA ) , induced expression of SA- and JA-related genes and suppressed accumulation of 1-aminocyclopropane-1-carboxylic acid ( ACC ) , the direct precursor of ethylene , and expression of ethylene-related genes .

OsEDR1-KO plants also showed suppressed production of ethylene .

Knockout of OsEDR1 suppressed the ACC synthase ( ACS ) gene family , which encodes the rate-limiting enzymes of ethylene biosynthesis by catalysing the formation of ACC .

The lesion phenotype and enhanced bacterial resistance of the OsEDR1-KO plants was partly complemented by the treatment with ACC .

ACC treatment was associated with decreased SA and JA biosynthesis in OsEDR1-KO plants .

In contrast , aminoethoxyvinylglycine , the inhibitor of ethylene biosynthesis , promoted expression of SA and JA synthesis-related genes in OsEDR1-KO plants .

These results suggest that ethylene is a negative signalling molecule in rice bacterial resistance .

In the rice-Xoo interaction , OsEDR1 transcriptionally promotes the synthesis of ethylene that , in turn , suppresses SA- and JA-associated defence signalling .


Below-ground microbes can induce systemic resistance against foliar pests and pathogens on diverse plant hosts .

The prevalence of induced systemic resistance ( ISR ) among plant-microbe-pest systems raises the question of host specificity in microbial induction of ISR .

To test whether ISR is limited by plant host range ( , ) we tested the ISR-inducing ectomycorrhizal fungus Laccaria bicolor on the nonmycorrhizal plant Arabidopsis thaliana .

We used the cabbage looper Trichoplusia ni and bacterial pathogen Pseudomonas syringae pv . tomato DC3000 ( Pto ) as readouts for ISR on Arabidopsis .

We found that root inoculation with L. bicolor triggered ISR against T. ni and induced systemic susceptibility ( ISS ) against the bacterial pathogen Pto .

We found that L. bicolor-triggered ISR against T. ni was dependent on jasmonic acid signaling and salicylic acid biosynthesis and signaling .

Heat-killed L. bicolor and chitin were sufficient to trigger ISR against T. ni and ISS against Pto .

The chitin receptor CERK1 was necessary for L. bicolor-mediated effects on systemic immunity .

Collectively our findings suggest that some ISR responses might not require intimate symbiotic association , but rather might be the result of root perception of conserved microbial signals .


Bensulfuron-methyl ( BSM ) is widely used in paddy soil for weed control .

BSM residue in the soil has been known to inhibit the growth of sensitive crop plants .

However , it is unknown whether BSM residue can affect the agrosystem in general .

In this study , we have found significant effects of BSM on the infestation of Bemisia tabaci , Myzus persicae , and Tobacco mosaic virus ( TMV ) in Nicotiana tabacum .

The soil was treated with BSM before the pest inoculation .

The herbicide-treated tobaccos showed resistance to B. tabaci , but this resistance could not be detected until 15-day post-infestation when smaller number of adults B. tabaci appeared .

In M. persicae assay , the longevity of all development stages of insects , and the fecundity of insects were not significantly affected when feeding on BSM-treated plants .

In TMV assay , the BSM treatment also reduced virus-induced lesions in early infection time .

However , the titer of TMV in BSM treated plants increased greatly over time and was over 40-fold higher than the mock-infected control plants after 20 days .

Further studies showed that BSM treatment increased both jasmonic acid ( JA ) and salicylic acid ( SA ) levels in tobacco , as well as the expression of target genes in the JA and SA signaling pathways , such as NtWIPK , NtPR1a , and NtPAL .

NtPR1a and NtPAL were initially suppressed after virus-inoculation , while NtRDR1 and NtRDR6 , which play a key role in fighting virus infection , only showed up- or were down-regulated 20 days post virus-inoculation .

Taken together , our results suggested that BSM residue in the soil may affect the metabolism of important phytohormones such as JA and SA in sensitive plants and consequently affect the plant immune response against infections such as whitefly , aphids , and viruses .


Gibberellic acid ( GA3 ) , a plant growth regulator , is widely used in agriculture in many countries to accelerate the growth of fruits and vegetables .

We designed histological , immunohistochemical , and biochemical studies to evaluate the deleterious effects of GA3 on the livers of adult pregnant rats and their offspring and to assess the possible ameliorative effect of Nigella sativa Linn . ( NsL.oil ) against these effects .

Twenty-four pregnant albino rats were utilized , randomly divided into four groups : The first group was used as a negative control group , while the second group ( positive control group ) was provided NsL.oil at a dose of 100 mg/kg of bodyweight .

Animals in the third group ( GA3 group ) were provided 200 ppm of GA3 dissolved in distilled water from the 7th day of pregnancy until 1 day after delivery .

Animals in the last group ( GA3 + NsL.oil group ) were provided GA3 and NsL-oil at the same doses as mentioned above .

One day after delivery , each group of lactating mothers and their pups were sacrificed .

Liver specimens were subjected to histopathological , immunohistochemical , and biochemical examinations .

The livers of rats from the GA3 group showed various degenerative changes , being predominant in the livers of the mothers compared with the offspring .

The pathological changes in the livers of the offspring suggested transplacental passage of GA3 .

The results reveal that GA3 ingestion induced a significant increase in alanine aminotransferase ( ALT ) and aspartate transaminase ( AST ) activities in the serum of both groups of mothers and their pups , with a significant increment in lipid peroxidation as evidenced by enhanced malondialdehyde ( MDA ) levels with significant decrements in superoxide dismutase ( SOD ) , catalase ( CAT ) , and glutathione peroxidase ( GPx ) enzymatic activities in comparison with control groups in the liver of mothers and their offspring .

Histopathological examination showed hydropic degeneration and inflammatory cellular infiltration .

Additionally , there was fibrosis around the portal area .

Moreover , immunolocalization revealed downregulation of the expression of the antiapoptotic marker Bcl-2 in hepatocytes and upregulation of the expression of the apoptotic marker Bax in the treated group .

Concomitant use of NsL.oil along with GA3 exerted a considerable reversing effect on histopathological and biochemical changes in the livers of mother groups and their pups .

The results of the present study highlight the consequences of exposure to GA3 during pregnancy on hepatic tissue in both mothers and their offspring .

Furthermore , the study suggests use of NsL.oil as a potential protective strategy against GA3-induced liver toxicity .


The wound response of tomato plants has been extensively studied , and provides a useful model to understand signal transduction events leading from injury to marker gene expression .

The principal markers that have been used in these studies are genes encoding proteinase inhibitor ( pin ) proteins .

Activation of pin genes occurs in the wounded leaf and in distant unwounded leaves of the plant .

This paper reviews current understanding of signalling pathways in the wounded leaf , and in the systemically responding unwounded leaves .

First , the nature of known elicitors and their potential roles in planta are discussed , in particular , oligogalacturonides , jasmonates and the peptide signal , systemin .

Inhibitors of wound-induced proteinase inhibitor ( pin ) expression are also reviewed , with particular reference to phenolics , sulphydryl reagents and fusicoccin .

In each section , results obtained from the bioassay are considered within the wider context of data from mutants and from transgenic plants with altered levels of putative signalling components .

Following this introduction , current models for pin gene regulation are described and discussed , together with a summary for the involvement of phosphorylation-dephosphorylation in wound signalling .

Finally , a new model for wound-induced pin gene expression is presented , arising from recent data from the author 's laboratory .


Biosynthesis of nicotine in tobacco requires N-methylputrescine oxidase ( MPO ) , which belongs to the copper-containing amine oxidase superfamily .

Previous studies identified tobacco MPO1 and its close homolog NtDAO1 ( formerly called MPO2 ) , of which MPO1 has been shown preferentially to oxidize N-methylated amines .

We show here that NtDAO1 , as well as a homologous Arabidopsis diamine oxidase ( DAO ) , accept non-N-methylated amines more efficiently than their corresponding N-methylated amines .

MPO1 is coordinately regulated with other nicotine biosynthesis genes with regard to COI1-MYC2-dependent jasmonate induction and its dependence on nicotine-specific ERF transcription factors , whereas NtDAO1 is constitutively expressed at low basal levels in tobacco plants .

Both MPO1 and NtDAO1 are targeted to peroxisomes by their C-terminal motifs , and the peroxisomal localization of MPO1 is required for it to function in nicotine biosynthesis in jasmonate-elicited cultured tobacco cells .

Restricted occurrence of the MPO subfamily in Nicotiana and Solanum indicates that , during the formation of the Solanaceae , MPO has evolved from a DAO , which functions in polyamine catabolism within peroxisomes , by optimizing substrate preference and gene expression patterns to be suitable for alkaloid formation .


Nodulation outer proteins secreted via type 3 secretion systems are involved in the process of symbiosis between legume plants and rhizobia .

To study the function of NopT in symbiosis , we mutated nopT in Mesorhizobium amphore CCNWGS0123 ( GS0123 ) , which can nodulate black locust ( Robinia pseudoacacia ) .

The nopT mutant induced higher levels of jasmonic acid , salicylic acid , and hydrogen peroxide accumulation in the roots of R. pseudoacacia compared with wild-type GS0123 .

The ΔnopT mutant induced higher disease-resistant gene expression 72 hours post-inoculation ( hpi ) , whereas GS0123 induced higher disease-resistant gene expression earlier , at 36 hpi .

Compared with the nopT mutant , GS0123 induced the up-regulation of most genes at 36 hpi and the down-regulation of most genes at 72 hpi .

Proteolytically active NopT_GS0123 induced hypersensitive responses when expressed transiently in tobacco leaves ( Nicotiana benthamiana ) .

Two NopT_GS0123 targets in R. pseudoacacia were identified , ATP-citrate synthase alpha chain protein 2 and hypersensitive-induced response protein .

Their interactions with NopT_GS0123 triggered resistance by the plant immune system .

In conclusion , NopT_GS0123 inhibited the host plant immune system and had minimal effect on nodulation in R. pseudoacacia .

Our results reveal the underlying molecular mechanism of NopT function in plant-symbiont interactions .


The peduncle of water hyacinth ( Eichhornia crassipes ) showed the downward bending within 24 hours after full flowering .

Previously it was suggested that the downward bending of peduncle might be induced by the differential growth of the epidermal cells of the portion because of the differential distribution of auxin in the upper side of the bending part of the peduncle .

In order to investigate the effect of auxin and gravity on the peduncle bending in Water hyacinth , we examined the growth reaction of peduncle and the effects of plant hormones on the bending of peduncle under simulated microgravity , and the sedimentable amyloplast on earth and three dimensional (3D)-clinostat .

As a result it was confirmed that the downward bending of peduncle in water hyacinth is the positive gravitropism , and that its phenomenon is caused by the differential distribution of auxin in the upper side of bending part of peduncle .

It was found that the amyloplast sediments toward gravity direction in the bending part of the peduncle .

From the present results , any direct relation between the sedimentable amyloplast and auxin transport were not cleared in the peduncle of water hyacinth .


Precise floral transition from vegetative growth phase to reproductive growth phase is very important in plant life cycle .

In flowering genetic pathways , DELLA proteins are master transcriptional regulators of gibberelic acid ( GA ) pathway , and FLOWERING LOCUS C ( FLC ) is a core repressor of vernalization pathway as well as downstream of DELLAs .

As a crucial messenger in plants , the possible involvement of melatonin ( N-acetyl-5-methoxytryptamine ) in flowering and underlying molecular mechanism are unknown in Arabidopsis .

In this study , we found that exogenous melatonin treatment delayed floral transition in Arabidopsis .

Exogenous melatonin treatment conferred protein stabilizations of DELLAs [ REPRESSOR of ga1 - 3 ( RGA ) and RGA-LIKE3 ( RGL3 ) ] , without regulating the transcripts of DELLAs and endogenous GA level .

Notably , exogenous melatonin delayed plant flowering and DELLA-activated transcripts of FLC were alleviated in della mutants , and those were exacerbated in DELLA overexpressing plants .

Taken together , this study provides direct link between melatonin and floral transition , and indicates the novel involvement of DELLAs-activated FLC in melatonin-mediated flowering in Arabidopsis .


Leaf senescence is a complicated developmental process that involves degenerative changes and nutrient recycling .

The progress of leaf senescence is controlled by various environmental cues and plant hormones , including ethylene , jasmonic acid , salicylic acid , abscisic acid , cytokinins , and strigolactones .

The production of strigolactones is induced in response to nitrogen and phosphorous deficiency .

Strigolactones also accelerate leaf senescence and regulate shoot branching and root architecture .

Leaf senescence is actively promoted in a nutrient-poor soil environment , and nutrients are transported from old leaves to young tissues and seeds .

Strigolactones might act as important signals in response to nutrient levels in the rhizosphere .

In this review , we discuss the possible roles of strigolactones during leaf senescence .


It has been shown that indoleacetic acid ( IAA ) does not occur in developing grains of Hordeum vulgare L. ( barley ) , but that an unidentified indolic compound does .

This compound , designated ' A ' , was also found to be a product of the metabolism of exogenous IAA by barley .

The expression of the gibberellic acid effect was delayed for at least 8 h if grains were imbibed in a solution of IAA , and during this time , the IAA was metabolised .

The enzyme system involved could be peroxidase , which was active in the grains at all stages of their development and at maturity , and partially purified extracts of peroxidase were found to have considerable IAA oxidase activity .


The plant-specific WUSCHEL-related homeobox ( WOX ) nuclear proteins have important roles in the transcriptional regulation of many developmental processes .

Among the rice ( Oryza sativa ) WOX proteins , a loss of OsWOX3A function in narrow leaf2 ( nal2 ) nal3 double mutants ( termed nal2/3 ) causes pleiotropic effects , such as narrow and curly leaves , opened spikelets , narrow grains , more tillers , and fewer lateral roots , but almost normal plant height .

To examine OsWOX3A function in more detail , transgenic rice overexpressing OsWOX3A ( OsWOX3A-OX ) were generated ; unexpectedly , all of them consistently exhibited severe dwarfism with very short and wide leaves , a phenotype that resembles that of gibberellic acid (GA)-deficient or GA-insensitive mutants .

Exogenous GA3 treatment fully rescued the developmental defects of OsWOX3A-OX plants , suggesting that constitutive overexpression of OsWOX3A downregulates GA biosynthesis .

Quantitative analysis of GA intermediates revealed significantly reduced levels of GA20 and bioactive GA1 in OsWOX3A-OX , possibly due to downregulation of the expression of KAO , which encodes ent-kaurenoic acid oxidase , a GA biosynthetic enzyme .

Yeast one-hybrid and electrophoretic mobility shift assays revealed that OsWOX3A directly interacts with the KAO promoter .

OsWOX3A expression is drastically and temporarily upregulated by GA3 and downregulated by paclobutrazol , a blocker of GA biosynthesis .

These data indicate that OsWOX3A is a GA-responsive gene and functions in the negative feedback regulation of the GA biosynthetic pathway for GA homeostasis to maintain the threshold levels of endogenous GA intermediates throughout development .


Bisphenol A ( BPA ) is an endocrine disruptor that is ubiquitous in the environment .

Previous studies have focused on the effects of BPA on plants to assess the ecological risk of BPA in the environment .

To evaluate the effects of BPA on plant biological characters more systematically , we investigated the biological characters of above-ground and under-ground organs of soybean plants exposed to BPA .

Meanwhile , the mechanisms for the observed changes were also analyzed from the view of hormone levels and photosynthesis .

The results showed that after exposure to 0.8 mg L(-1 ) BPA for three days , indole-3-acetic acid ( IAA ) and gibberellic acid levels in roots increased significantly , and the IAA level increased in leaves , so the character indices of roots and leaves both increased .

The IAA and ethylene levels in stems increased , but the character indices of stems did not increased .

With higher BPA concentrations , especially exposure to 17.2 mg L(-1 ) BPA , the levels of IAA , gibberellic acid , and zeatin decreased ( except for the increased zeatin in leaves ) , and abscisic acid and ethylene levels increased ; thus , all of the character indices significantly decreased .

By comparing the changes in various biological characters , we found that leaf area , root surface area , and root length changed most significantly .

In addition , changes in photosynthetic parameters provided initial causes for plant growth changes , and impacted biological characters .

The changes of character indices were stronger when the BPA exposure time was prolonged , and after the removal of BPA , the character indices showed some recovery .

Therefore , BPA exposure can regulate the changes in plant characters by influencing hormone levels and photosynthesis , and root surface area , root length , and leaf area were the most sensitive to BPA .


NaCl alleviates Cd toxicity in Sesvium portulacastrum by maintaining plant water status and redox balance , protecting chloroplasts structure and inducing some potential Cd ( 2 + ) chelators as GSH and proline .

It has been demonstrated that NaCl alleviates Cd-induced growth inhibition in the halophyte Sesuvium portulacastrum .

However , the processes that mediate this effect are still unclear .

In this work we combined physiological , biochemical and ultrastructural studies to highlight the effects of salt on the redox balance and photosynthesis in Cd-stressed plants .

Seedlings were exposed to different Cd concentrations ( 0 , 25 and 50 µM Cd ) combined with low ( 0.09 mM ) ( LS ) , or high ( 200 mM ) NaCl ( HS ) in hydroponic culture .

Plant-water relations , photosynthesis rate , leaf gas exchange , chlorophyll fluorescence , chloroplast ultrastructure , and proline and glutathione concentrations were analyzed after 1 month of treatment .

In addition , the endogenous levels of stress-related hormones were determined in plants subjected to 25 µM Cd combined with both NaCl concentrations .

In plants with low salt supply ( LS ) , Cd reduced growth , induced plant dehydration , disrupted chloroplast structure and functioning , decreased net CO2 assimilation rate ( A ) and transpiration rate ( E ) , inhibited the maximum potential quantum efficiency ( Fv/Fm ) and the quantum yield efficiency ( Φ PSII ) of PSII , and enhanced the non-photochemical quenching ( NPQ ) .

The addition of 200 mM NaCl ( HS ) to the Cd-containing medium culture significantly mitigated Cd phytotoxicity .

Hence , even at similar internal Cd concentrations , HS-Cd plants were less affected by Cd than LS-Cd ones .

Hence , 200 mM NaCl significantly alleviates Cd-induced toxicity symptoms , growth inhibition , and photosynthesis disturbances .

The cell ultrastructure was better preserved in HS-Cd plants but affected in LS-Cd plants .

The HS-Cd plants showed also higher concentrations of reduced glutathione ( GSH ) , proline and jasmonic acid ( JA ) than the LS-Cd plants .

However , under LS-Cd conditions , plants maintained higher concentration of salicylic acid ( SA ) and abscisic acid ( ABA ) than the HS-Cd ones .

We conclude that in S. portulacastrum alleviation of Cd toxicity by NaCl is related to the modification of GSH and proline contents as well as stress hormone levels thus protecting redox balance and photosynthesis .


Understanding the interactions between drought and acute ozone ( O(3 ) ) stress in terms of signaling molecules and cell death would improve the predictions of plant responses to climate change .

The aim was to investigate whether drought stress influences the responses of plants to acute episodes of O(3 ) exposure .

In this study , the behavior of 84 Mediterranean evergreen Quercus ilex plants was evaluated in terms of cross-talk responses among signaling molecules .

Half of the sample was subjected to drought ( 20 % of the effective daily evapotranspiration , for 15 days ) and was later exposed to an acute O(3 ) exposure ( 200 nL L(-1 ) for 5 h ) .

First , our results indicate that in well-water conditions , O(3 ) induced a signaling pathway specific to O(3)-sensitive behavior .

Second , different trends and consequently different roles of phytohormones and signaling molecules ( ethylene , ET ; abscisic acid , ABA ; salycilic acid , SA and jasmonic acid , JA ) were observed in relation to water stress and O(3 ) .

A spatial and functional correlation between these signaling molecules was observed in modulating O(3)-induced responses in well-watered plants .

In contrast , in drought-stressed plants , these compounds were not involved either in O(3)-induced signaling mechanisms or in leaf senescence ( a response observed in water-stressed plants before the O(3)-exposure ) .

Third , these differences were ascribable to the fact that in drought conditions , most defense processes induced by O(3 ) were compromised and/or altered .

Our results highlight how Q. ilex plants suffering from water deprivation respond differently to an acute O(3 ) episode compared to well-watered plants , and suggest new effect to be considered in plant responses to environmental changes .

This poses the serious question as to whether or not multiple high-magnitude O(3 ) events ( as predicted ) can change these cross-talk responses , thus opening it up possible further investigations .


KEY MESSAGE : Arabidopsis gulliver3 - D/dwarf4 - D displays growth-promoting phenotypes due to activation tagging of a key brassinosteroid biosynthetic gene DWARF4 .

In gul3-D/dwf4-D , the Jasmonate and Salicylate signaling pathways were relatively activated and suppressed , respectively .

Energy allocation between growth and defense is elegantly balanced to achieve optimal development in plants .

Brassinosteroids ( BRs ) , steroidal hormones essential for plant growth , are regulated by other plant hormones , including auxin and jasmonates ( JA ) ; auxin stimulates the expression of a key brassinosteroid ( BR ) biosynthetic gene , DWARF4 ( DWF4 ) , whereas JA represses it .

To better understand the interaction mechanisms between growth and defense , we isolated a fast-growing mutant , gulliver3-D ( gul3-D ) , that resulted from the activation tagging of DWF4 , and examined the response of this mutant to defense signals , including JA , Pseudomonas syringae pv . tomato ( Pst DC3000 ) infection , and wounding .

The degree of root growth inhibition following MeJA treatment was significantly decreased in gul3 - 1D/dwf4 - 5D relative to the wild type , suggesting that JA signaling is partially desensitized in gul3 - 1D .

Quantitative RT-PCR analysis of the genes involved in JA and salicylic acid ( SA ) responses , including MYC2 , PDF1.2 , CORI3 , PR1 , and PR2 , revealed that JA signaling was preferentially activated in gul3 - 1D , whereas SA signaling was suppressed .

As a result , gul3 - 1D was more susceptible to a biotrophic pathogen , Pst DC3000 .

Based on our results , we propose a model in which BR and JA cooperate to balance energy allocation between growth and defense responses .

In ambient conditions , BRs promote plant growth ; however , when stresses trigger JA signaling , JA compromises BR signaling by downregulating DWF4 expression .


Bacterial wilt caused by the bacterial pathogen Ralstonia solanacearum is one of the most devastating crop diseases worldwide .

The molecular mechanisms controlling the early stage of R. solanacearum colonization in the root remain unknown .

Aiming to better understand the mechanism of the establishment of R. solanacearum infection in root , we established four stages in the early interaction of the pathogen with Arabidopsis roots and determined the transcriptional profiles of these stages of infection .

A total 2,698 genes were identified as differentially expressed genes during the initial 96 h after infection , with the majority of changes in gene expression occurring after pathogen-triggered root-hair development observed .

Further analysis of differentially expressed genes indicated sequential activation of multiple hormone signaling cascades , including abscisic acid ( ABA ) , auxin , jasmonic acid , and ethylene .

Simultaneous impairment of ABA receptor genes promoted plant wilting symptoms after R. solanacearum infection but did not affect primary root growth inhibition or root-hair and lateral root formation caused by R. solanacearum .

This indicated that ABA signaling positively regulates root defense to R. solanacearum .

Moreover , transcriptional changes of genes involved in primary root , lateral root , and root-hair formation exhibited high temporal dynamics upon infection .

Taken together , our results suggest that successful infection of R. solanacearum on roots is a highly programmed process involving in hormone crosstalk .


Gibberellic acid ( GA ) regulates many aspects of plant growth and development .

The DELLA proteins act to restrain plant growth , and GA relieves this repression by promoting their degradation via the 26S proteasome pathway .

The elucidation of the crystalline structure of the GA soluble receptor GID1 protein represents an important breakthrough for understanding the way in which GA is perceived and how it induces the destabilization of the DELLA proteins .

Recent advances have revealed that the DELLA proteins are involved in protein-protein interactions within various environmental and hormone signaling pathways .

In this review , we highlight our current understanding of the ' relief of repression ' model that aims to explain the role of GA and the function of the DELLA proteins , incorporating the many aspects of cross-talk shown to exist in the control of plant development and the response to stress .


Oxophytodienoate reductases ( OPRs ) are a small group of flavin-dependent oxidoreductases in plants .

In this study , a new member of the OPR gene family ( HvOPR2 ) was cloned from barley ( Hordeum vulgare L. ) using reverse transcription polymerase chain reaction ( RT-PCR ) .

The full-length cDNA of HvOPR2 was 1,206 bp with an open reading frame of 1,101 bp , encoding a 366 amino acids long polypeptide with a predicted molecular weight of 40.52 and a theoretical isoelectric point of 6.21 .

The corresponding genomic clone of HvOPR2 was isolated using the PCR amplification technique and was found to consist of five exons and four introns .

Bioinformatic analysis revealed that the deduced HvOPR2 has a considerable homology with other plant OPRs and possessed the flavin oxidoreductase/NADH oxidase substrate-binding domain .

Phylogenetic analysis showed that HvOPR2 codes for the OPR of subgroup I , which contains enzymes that are not required for jasmonic acid biosynthesis .

Time-course transcriptional profiling of HvOPR2 was analyzed in response to a variety of abiotic stresses and hormonal treatments by semi-quantitative RT-PCR .

The HvOPR2 gene was induced in response to drought , hydrogen peroxide , and wounding .

Moreover , the corresponding mRNA transcripts were increased in response to jasmonic acid and salicylic acid , but not in response to abscisic acid .

These results strongly suggested a role for HvOPR2 in barley defense/response to abiotic stresses and signaling molecules .


The phytoalexin-deficient Arabidopsis mutant pad3 - 1 , which is affected in the production of the indole-type phytoalexin camalexin , has previously been shown not to display altered susceptibility to either the bacterium Pseudomonas syringae ( Glazebrook & Ausubel 1994 ; Proc .

Acad . Sci . USA , 91 : 8955 - 8959 ) or the biotrophic fungi Peronospora parasitica ( Glazebrook et al. 1997 ; Genetics , 146 : 381 - 392 ) and Erysiphe orontii ( Reuber et al. 1998 ; Plant J. 16 : 473 - 485 ) .

We now show that this mutant is markedly more susceptible than its wild-type parental line to infection by the necrotrophic fungus Alternaria brassicicola , but not to Botrytis cinerea .

A strong camalexin response was elicited in wild-type plants inoculated with either Alternaria brassicicola or Botrytis cinerea , whereas no camalexin could be detected in pad3 - 1 challenged with these fungi .

Hence , PAD3 appears to be a key determinant in resistance to at least A. brassicicola .

The induction of salicylate-dependent and jasmonate/ethylene-dependent defense genes was not reduced in Alternaria-challenged pad3 - 1 plants compared to similarly treated wild-type plants .

Camalexin production could not be triggered by exogenous application of either salicylate , ethylene or jasmonate and was not , or not strongly , reduced in mutants with defects in perception of these defense-related signal molecules .

Camalexin-production appears to be controlled by a pathway that exhibits little cross-talk with salicylate- , ethylene- and jasmonate-dependent signalling events .


A nonpathogenic rhizobacterium , Pseudomonas putida LSW17S , elicited systemic protection against Fusarium wilt and pith necrosis caused by Fusarium oxysporum f. sp. lycopersici and P. corrugata in tomato ( Lycopersicon esculentum L. ) .

LSW17S also confers disease resistance against P. syringae pv . tomato DC3000 ( DC3000 ) on Arabidopsis ecotype Col-0 .

To investigate mechanisms underlying disease protection , expression patterns of defense-related genes PR1 , PR2 , PR5 , and PDF1.2 and cellular defense responses such as hydrogen peroxide accumulation and callose deposition were investigated .

LSW17S treatment exhibited the typical phenomena of priming .

Strong and faster transcription of defense-related genes was induced and hydrogen peroxide or callose were accumulated in Arabidopsis treated with LSW17S and infected with DC3000 .

In contrast , individual actions of LSW17S and DC3000 did not elicit rapid molecular and cellular defense responses .

Priming by LSW17S was translocated systemically and retained for more than 10 days .

Treatment with LSW17S reduced pathogen proliferation in Arabidopsis ecotype Col-0 expressing bacterial NahG ; however , npr1 , etr1 , and jar1 mutations impaired inhibition of pathogen growth .

Cellular and molecular priming responses support these results .

In sum , LSW17S primes Arabidopsis for NPR1- , ethylene- , and jasmonic acid-dependent disease resistance , and efficient molecular and cellular defense responses .


The abscisic acid (ABA)- , stress- , and ripening-induced ( ASR ) protein is a plant-specific hydrophilic transcriptional factor involved in fruit ripening and the abiotic stress response .

To date , there have been no studies on the role of ASR genes in delayed flowering time .

Here , we found that the ASR from banana , designated as MaASR , was preferentially expressed in the banana female flowers from the eighth , fourth , and first cluster of the inflorescence .

MaASR transgenic lines ( L14 and L38 ) had a clear delayed-flowering phenotype .

The number of rosette leaves , sepals , and pedicel trichomes in L14 and L38 was greater than in the wild type ( WT ) under long day ( LD ) conditions .

The period of buds , mid-flowers , and full bloom of L14 and L38 appeared later than the WT .

cDNA microarray and quantitative real-time PCR ( qRT-PCR ) analyses revealed that overexpression of MaASR delays flowering through reduced expression of several genes , including photoperiod pathway genes , vernalization pathway genes , gibberellic acid pathway genes , and floral integrator genes , under short days ( SD ) for 28 d ( from vegetative to reproductive transition stage ) ; however , the expression of the autonomous pathway genes was not affected .

This study provides the first evidence of a role for ASR genes in delayed flowering time in plants .


This study was designed to examine the effects of NaCl pretreatment on the seed germination of white clover ( Trifolium repens cv . Ladino ) under water stress induced by 19 % polyethylene glycol ( PEG ) 6000 .

Lower concentrations of NaCl ( 0.5 , 1 , and 2.5 mM ) pretreatment significantly alleviated stress-induced decreases in germination percentage , germination vigor , germination index , and radicle length of seedlings after seven days of germination under water stress .

The soaking with 1 mM of NaCl exhibited most the pronounced effects on improving seed germination and alleviating stress damage .

NaCl-induced seeds germination and growth could be associated with the increases in endogenous gibberellic acid ( GA ) and indole-3-acetic acid ( IAA ) levels through activating amylases leading to improved amylolysis under water stress .

Seedlings pretreated with NaCl had a significantly lower osmotic potential than untreated seedlings during seed germination , which could be related to significantly higher soluble sugars and free proline content in NaCl-treated seedlings under water stress .

For antioxidant metabolism , NaCl pretreatment mainly improved superoxide dismutase , peroxidase , ascorbate peroxidase , and glutathione reductase activities , transcript levels of FeSOD , APX , and DHAR , and the content of ascorbic acid , reduced glutathione , and oxidized glutathione during seed germination under water stress .

The results indicated that seeds soaking with NaCl could remarkably enhance antioxidant metabolism , thereby decreasing the accumulation of reactive oxygen species and membrane lipid peroxidation during germination under water stress .

In addition , NaCl-upregulated dehydrin-encoded genes SK2 expression could be another important mechanism of drought tolerance during seeds germination of white clover in response to water stress .


Phytohormones , such as salicylic acid ( SA ) , ethylene ( ET ) and jasmonic acid ( JA ) , play key roles in plant defence following pathogen attack .

The involvement of these hormones in susceptibility following Fusarium oxysporum ( Fo ) infection has mostly been studied in Arabidopsis thaliana .

However , Fo causes vascular wilt disease in a broad range of crops , including tomato ( Solanum lycopersicum ) .

Surprisingly little is known about the involvement of these phytohormones in the susceptibility of tomato towards Fo f. sp. lycopersici ( Fol ) .

Here , we investigate their involvement by the analysis of the expression of ET , JA and SA marker genes following Fol infection , and by bioassays of tomato mutants affected in either hormone production or perception .

Fol inoculation triggered the expression of SA and ET marker genes , showing the activation of these pathways .

NahG tomato , in which SA is degraded , became hypersusceptible to Fol infection and showed stronger disease symptoms than wild-type .

In contrast , ACD and Never ripe ( Nr ) mutants , in which ET biosynthesis and perception , respectively , are impaired , showed decreased disease symptoms and reduced fungal colonization on infection .

The susceptibility of the def1 tomato mutant , and a prosystemin over-expressing line , in which JA signalling is compromised or constitutively activated , respectively , was unaltered .

Our results show that SA is a negative and ET a positive regulator of Fol susceptibility .

The SA and ET signalling pathways appear to act synergistically , as an intact ET pathway is required for the induction of an SA marker gene , and vice versa .


Germination of Amaranthus caudatus is inhibited by light , far-red being the most effective part of the spectrum .

At temperatures of 25 ° and below there is a low final germination percentage under continuous far-red whereas above 25 ° there is only a delaying effect .

In the presence of a saturating concentration of gibberellic acid ( GA3 ) at 25 ° seeds germinate under continuous far-red although they are delayed .

At 25 ° seeds exposed to 48 hr far-red fail to germinate when transferred to darkness .

This induced dormancy can be broken by a single short exposure to red light given at any time after the far-red illumination .

This effect of short red can be reversed by a subsequent short period of far-red indicating that the seeds are phytochrome controlled .

Although most seeds have escaped from the reversing effect of short far-red after an intervening dark period of 5 hours , germination is greatly reduced by continuous far-red at this time .

Results of exposing seeds to varying periods of far-red before and after dark imbibition are interpreted in terms of a continual production of phytochrome in its active P fr form and a requirement for P fr action over a long period of time .

Effects of intermittent and continuous low intensity far-red on the inhibition of germination provides further evidence for a low energy photoreaction involving phytochrome .

Effects on Germination Index of continuous illumination with various light sources maintaining different P fr /P total ratios have been investigated .

The results suggest that the proportion of phytochrome in the P fr form is the most important factor in the regulation of germination .

A scheme for the phytochrome control of germination in Amaranthus caudatus is presented and possible explanations for the dependence on P fr /P total ratio are discussed .


In plants , ethylene and jasmonate control the defense responses to multiple stressors , including insect predation .

Among the defense proteins known to be regulated by ethylene is maize insect resistance 1-cysteine protease ( Mir1-CP ) .

This protein is constitutively expressed in the insect-resistant maize ( Zea mays ) genotype Mp708 ; however , its abundance significantly increases during fall armyworm ( Spodoptera frugiperda ) herbivory .

Within 1 h of herbivory by fall armyworm , Mir1-CP accumulates at the feeding site and continues to increase in abundance until 24 h without any increase in its transcript ( mir1 ) levels .

To resolve this discrepancy and elucidate the role of ethylene and jasmonate in the signaling of Mir1-CP expression , the effects of phytohormone biosynthesis and perception inhibitors on Mir1-CP expression were tested .

Immunoblot analysis of Mir1-CP accumulation and quantitative reverse-transcriptase polymerase chain reaction examination of mir1 levels in these treated plants demonstrate that Mir1-CP accumulation is regulated by both transcript abundance and protein expression levels .

The results also suggest that jasmonate functions upstream of ethylene in the Mir1-CP expression pathway , allowing for both low-level constitutive expression and a two-stage defensive response , an immediate response involving Mir1-CP accumulation and a delayed response inducing mir1 transcript expression .


BACKGROUND : Jasmonic acid ( JA ) and methyl jasmonate ( MeJA ) regulate plant development , resistance to stress , and insect attack by inducing specific gene expression .

However , little is known about the mechanism of plant defense against herbivore attack at a protein level .

Using a high-resolution 2-D gel , we identified 62 MeJA-responsive proteins and measured protein expression level changes .

RESULTS : Among these 62 proteins , 43 proteins levels were increased while 11 proteins were decreased .

We also found eight proteins uniquely expressed in response to MeJA treatment .

Data are available via ProteomeXchange with identifier PXD001793 .

The proteins identified in this study have important biological functions including photosynthesis and energy related proteins ( 38.4 % ) , protein folding , degradation and regulated proteins ( 15.0 % ) , stress and defense regulated proteins ( 11.7 % ) , and redox-responsive proteins ( 8.3 % ) .

The expression levels of four important genes were determined by qRT-PCR analysis .

The expression levels of these proteins did not correlate well with their translation levels .

To test the defense functions of the differentially expressed proteins , expression vectors of four protein coding genes were constructed to express in-fusion proteins in E. coli .

The expressed proteins were used to feed Ostrinia furnacalis , the Asian corn borer ( ACB ) .

Our results demonstrated that the recombinant proteins of pathogenesis-related protein 1 ( PR1 ) and thioredoxin M-type , chloroplastic precursor ( TRXM ) showed the significant inhibition on the development of larvae and pupae .

CONCLUSIONS : We found MeJA could not only induce plant defense mechanisms to insects , it also enhanced toxic protein production that potentially can be used for bio-control of ACB .


Jasmonic acid ( JA ) and nitric oxide ( NO ) are well-characterized signaling molecules in plant defense responses .

However , their roles in plant defense against root-knot nematode ( RKN , Meloidogyne incognita ) infection are largely unknown .

In this study , we found that the transcript levels of the JA- and NO-related biosynthetic and signaling component genes were induced after RKN infection .

Application of exogenous JA and sodium nitroprusside ( SNP ; a NO donor ) significantly decreased the number of egg masses in tomato roots after RKN infection and partially alleviated RKN-induced decreases in plant fresh weight and net photosynthetic rate .

These molecules also alleviated RKN-induced increases in root electrolyte leakage and membrane peroxidation .

Importantly , NO scavenger partially inhibited JA-induced RKN defense .

The pharmacological inhibition of JA biosynthesis significantly increased the plants ' susceptibility to RKNs , which was effectively alleviated by SNP application , showing that NO may be involved in the JA-dependent RKN defense pathway .

Furthermore , both JA and SNP induced increases in protease inhibitor 2 ( PI2 ) gene expression after RKN infestation .

Silencing of PI2 compromised both JA- and SNP-induced RKN defense responses , suggesting that the PI2 gene mediates JA- and NO-induced defense against RKNs .

This work will be important for deepening the understanding of the mechanisms involved in basal defense against RKN attack in plants .


Beet necrotic yellow vein virus ( BNYVV ) and Beet soil-borne mosaic virus ( BSBMV ) are closely related species , but disease development induced in their host sugar beet displays striking differences .

Beet necrotic yellow vein virus induces excessive lateral root ( LR ) formation , whereas BSBMV-infected roots appear asymptomatic .

A comparative transcriptome analysis was performed to elucidate transcriptomic changes associated with disease development .

Many differentially expressed genes ( DEGs ) were specific either to BNYVV or BSBMV , although both viruses shared a high number of DEGs .

Auxin biosynthesis pathways displayed a stronger activation by BNYVV compared to BSBMV-infected plants .

Several genes regulated by auxin signalling and required for LR formation were exclusively altered by BNYVV .

Both viruses reprogrammed the transcriptional network , but a large number of transcription factors involved in plant defence were upregulated in BNYVV-infected plants .

A strong activation of pathogenesis-related proteins by both viruses suggests a salicylic acid or jasmonic acid mediated-defence response , but the data also indicate that both viruses counteract the SA-mediated defence .

The ethylene signal transduction pathway was strongly downregulated which probably increases the susceptibility of sugar beet to Benyvirus infection .

Our study provides a deeper insight into the interaction of BNYVV and BSBMV with the economically important crop sugar beet .


Brassinosteroids ( BRs ) and jasmonates ( JAs ) regulate plant growth , development , and defense responses , but how these phytohormones mediate the growth-defense tradeoff is unclear .

Here , we identified the Arabidopsis ( Arabidopsis thaliana ) dwarf at early stages1 ( dwe1 ) mutant , which exhibits enhanced expression of defensin genes PLANT DEFENSIN1.2a ( PDF1.2a ) and PDF1.2b The dwe1 mutant showed increased resistance to herbivory by beet armyworms ( Spodoptera exigua ) and infection by botrytis ( Botrytis cinerea ) .

DWE1 encodes ROTUNDIFOLIA3 , a cytochrome P450 protein essential for BR biosynthesis .

The JA-inducible transcription of PDF1.2a and PDF1.2b was significantly reduced in the BRASSINOSTEROID INSENSITIVE1-ETHYL METHANESULFONATE-SUPPRESSOR1 ( BES1 ) gain-of-function mutant bes1- D , which was highly susceptible to S. exigua and B. cinerea BES1 directly targeted the terminator regions of PDF1.2a/PDF1.2b and suppressed their expression .

PDF1.2a overexpression diminished the enhanced susceptibility of bes1- D to B. cinerea but did not improve resistance of bes1- D to S. exigua In response to S. exigua herbivory , BES1 inhibited biosynthesis of the JA-induced insect defense-related metabolite indolic glucosinolate by interacting with transcription factors MYB DOMAIN PROTEIN34 ( MYB34 ) , MYB51 , and MYB122 and suppressing expression of genes encoding CYTOCHROME P450 FAMILY79 SUBFAMILY B POLYPEPTIDE3 ( CYP79B3 ) and UDP-GLUCOSYL TRANSFERASE 74B1 ( UGT74B1 ) .

Thus , BR contributes to the growth-defense tradeoff by suppressing expression of defensin and glucosinolate biosynthesis genes .


BACKGROUND : The valuable medicinal plant Panax ginseng has high pharmaceutical efficacy because it produces ginsenosides .

However , its yields decline because of a root-rot disease caused by Ilyonectria mors-panacis .

Because species within Ilyonectria showed variable aggressiveness by altering ginsenoside concentrations in inoculated plants , we investigated how such infections might regulate the biosynthesis of ginsenosides and their related signaling molecules .

METHODS : Two-year-old ginseng seedlings were treated with I. mors-panacis and I. robusta .

Roots from infected and pathogen-free plants were harvested at 4 and 16 days after inoculation .

We then examined levels or/and expression of genes of ginsenosides , salicylic acid ( SA ) , jasmonic acid ( JA ) , and reactive oxygen species ( ROS ) .

We also checked the susceptibility of those pathogens to ROS .

RESULTS : Ginsenoside biosynthesis was significantly suppressed and increased in response to infection by I. mors-panacis and I. robusta , respectively .

Regulation of JA was significantly higher in I. robusta-infected roots , while levels of SA and ROS were significantly higher in I. mors-panacis-infected roots .

Catalase activity was significantly higher in I. robusta-infected roots followed in order by mock roots and those infected by I. mors-panacis .

Moreover , I. mors-panacis was resistant to ROS compared with I. robusta .

CONCLUSION : Infection by the weakly aggressive I. robusta led to the upregulation of ginsenoside production and biosynthesis , probably because only a low level of ROS was induced .

In contrast , the more aggressive I. mors-panacis suppressed ginsenoside biosynthesis , probably because of higher ROS levels and subsequent induction of programmed cell death pathways .

Furthermore , I. mors-panacis may have increased its virulence by resisting the cytotoxicity of ROS .


Mitogen-activated protein kinases ( MAPKs ) play an important role in defense responses to biotic and abiotic stresses .

In order to investigate the role of SlMAPK3 in tomato plant resistance to Botrytis cinerea , two lines of slmapk3 mutants and wild-type ( WT ) tomato plants were used .

The results showed that slmapk3 mutants were more susceptible to B. cinerea and that knockout of SlMAPK3 reduced the activities of defense enzymes and enhanced the accumulation of reactive oxygen species ( ROS ) .

Furthermore , we detected the expressions of salicylic acid ( SA ) and jasmonic acid ( JA ) signaling-related genes and found that knockout of SlMAPK3 enhanced the expressions of SlPR1 , SlPAD4 and SlEDS1 , whereas reduced the expressions of SlLoxC , SlPI I and SlPI II and enhanced the expressions of SlJAZ1 and SlMYC2 .

We postulate that SlMAPK3 plays a positive role in tomato plant resistance to B. cinerea through regulating ROS accumulation and SA and JA defense signaling pathways .


A general prediction of the specialist/generalist paradigm indicates that plant responses to insect herbivores may depend on the degree of ecological specialization of the insect attacker .

However , results from a single greenhouse experiment evaluating the responses of the model plant Arabidopsis thaliana to three specialist ( Plutella xylostella , Pieris rapae , and Brevicoryne brassicae ) and three generalist ( Trichoplusia ni , Spodoptera exigua , and Myzus persicae ) insect species did not support the previous prediction .

Using an ecological genomic approach , we assessed plant responses in terms of herbivore-induced changes in genome-wide gene expression , defense-related pathways , and concentrations of glucosinolates ( i.e. , secondary metabolites that are ubiquitously present in cruciferous plants ) .

Our results showed that plant responses were not influenced by the degree of specialization of insect herbivores .

In contrast , responses were more strongly shaped by insect taxa ( i.e. , aphid vs. lepidopteran species ) , likely due to their different feeding modes .

Interestingly , similar patterns of plant responses were induced by the same insect herbivore species in terms of defense signaling ( jasmonic acid pathway ) , aliphatic glucosinolate metabolism ( at both the gene expression and phenotypic levels ) and genome-wide responses .

Furthermore , plant responses to insect herbivores belonging to the same taxon ( i.e. , four lepidopteran species ) were not explained by herbivore specialization or phylogenetic history .

Overall , this study suggests that different feeding modes of insect taxa as well as herbivore-specific plant responses , which may result from distinct ecological/evolutionary interactions between A. thaliana ( or a close relative ) and each of the lepidopteran species , may explain why observed responses deviate from those predicted by the specialist/generalist paradigm .


A multiscaled ecophysiological model of barley ( Hordeum vulgare ) development is presented here .

The model is based on the new formalism of relational growth grammars ( RGG ) , an extension of L-systems , and implemented using the new modelling language XL .

It is executable in the interactive modelling platform GroIMP .

The model consists of a set of morphogenetic rules , combined with a metabolic regulatory network , which simulates the biosynthesis of gibberellic acid ( GA1 ) .

GA1 and two of its metabolic precursors are transported along the developing simulated structure .

Local concentrations of GA1 determine internode elongation .

Furthermore , virtual barley individuals are chosen interactively from a population , based on genotype , and ( sexual or asexual ) reproduction is simulated .

Genotype and phenotype of the population are visualized .

Seven Mendelian genes have been implemented in the model so far ; some of these directly influence the GA-regulation network .

The model exemplifies and validates the new formalism and modelling language .

RGG have the capability to represent genetic , metabolic and morphological aspects of plant development and reproduction , all within the same framework .


OBJECTIVES : This study investigated , whether the growth rate of Lemna gibba L. ( duckweed ) can be influenced by the application of homeopathic potencies of gibberellic acid , kinetin , argentum nitricum , and lemna minor .

METHODS : Duckweed was grown in either potencies ( 14x-30x , decimal steps ) or water controls ( unsuccussed and succussed ) over seven days .

Frond ( leaf-like structure ) growth was measured using a non-destructive image analysis system .

Growth rates were calculated for three time intervals ( 0 - 7 , 0 - 3 , 3 - 7 days ) .

Five to six independent , randomized and blinded experiments were analysed for each of the four tested substances .

Water control experiments were performed repeatedly to test the reliability of the experimental set-up ( systematic negative controls ) .

RESULTS : The systematic negative control experiments did not yield any significant effects .

Hence , false positive results could be excluded .

The test system had a low coefficient of variation ( 1.5 % ) .

Out of the four tested substances gibberellic acid had the most pronounced effect ( p=0.0002 , F-test ) on the main outcome parameter frond growth rate ( r(area ) day 0 - 7 ) .

Potency levels 15x , 17x , 18x , 23x and 24x reduced growth rate of Lemna gibba ( p<0.05 against the pooled water control , LSD test ) .

CONCLUSIONS : Lemna gibba may be considered as a suitable test organism for further studies on the efficacy of homeopathic potencies .

Evidence accumulates , that adjacent potency levels may strongly differ in their biological activity .

Potential consequences for therapeutical application might be worth investigating .


Two-week-old dwarf peas ( Pisum sativum cv Little Marvel ) were sprayed with gibberellic acid ( GA(3 ) ) , and after 3 or 4 days the upper stem and young leaf samples were analyzed for indole-3-acetic acid ( IAA ) and indole-3-acetyl aspartic acid by an isotope dilution high performance liquid chromatography method .

GA(3 ) increased IAA levels as much as 8-fold and decreased indole-3-acetyl aspartic acid levels .


Studies of the singlet oxygen ( (1)O2)-overproducing flu and chlorina1 ( ch1 ) mutants of Arabidopsis ( Arabidopsis thaliana ) have shown that (1)O2-induced changes in gene expression can lead to either programmed cell death ( PCD ) or acclimation .

A transcriptomic analysis of the ch1 mutant has allowed the identification of genes whose expression is specifically affected by each phenomenon .

One such gene is OXIDATIVE SIGNAL INDUCIBLE1 ( OXI1 ) encoding an AGC kinase that was noticeably induced by excess light energy and (1)O2 stress conditions leading to cell death .

Photo-induced oxidative damage and cell death were drastically reduced in the OXI1 null mutant ( oxi1 ) and in the double mutant ch1*oxi1 compared with the wild type and the ch1 single mutant , respectively .

This occurred without any changes in the production rate of (1)O2 but was cancelled by exogenous applications of the phytohormone jasmonate .

OXI1-mediated (1)O2 signaling appeared to operate through a different pathway from the previously characterized OXI1-dependent response to pathogens and H2O2 and was found to be independent of the EXECUTER proteins .

In high-light-stressed plants , the oxi1 mutation was associated with reduced jasmonate levels and with the up-regulation of genes encoding negative regulators of jasmonate signaling and PCD .

Our results show that OXI1 is a new regulator of (1)O2-induced PCD , likely acting upstream of jasmonate .


The goal of this study was to determine whether the application of gibberellic acid ( GA(3 ) ) to seeds of common wheat varieties with different vernalization and photoperiod requirements affects the transition from vegetative to generative stage .

Three varieties of wheat with different photoperiod sensitivities and vernalization were selected for the experiment-the winter varieties , Mironovskaya and Bezostaya , and the spring variety , Sirael . Seeds were treated with different concentrations of GA(3 ) and plants were grown under long-day conditions with monitoring of their photosynthetic activity ( F(v)/F(m ) , P(n ) , E , g(s ) ) .

We monitored the activity of the photosynthetic apparatus by checking the plants to see if they were growing properly .

The phenological stages of the wheat species were checked for indications of a transition from the vegetative to the generative stage .

Selected concentrations of GA(3 ) had no effect on the compensation of the vernalization process ( transition to the generative phase ) .

Chlorophyll fluorescence was one of the factors for monitoring stress .

The variety , Bezostaya , is similar to the spring variety , Sirael , in its trends and values .

The growth conditions of Bezostaya and Sirael were not affected by the activity of the photosynthetic apparatus .

The development of growing points in winter varieties occurred at the prolonged single ridge stage .

The spring variety reached the stage of head emergence after sixty days of growth ( changes to the flowering phase did not appear in winter wheat ) .

Application of GA(3 ) to the seeds had no effect on the transition of the growing point to the double-ridge generative stage .

The present study highlights the priming effect of GA(3 ) on seeds of common wheat varieties with different vernalization and photoperiod requirements as it affected the transition from vegetative to generative stage .


Arbuscular mycorrhizal ( AM ) symbioses are mutualistic associations between soil fungi and most vascular plants .

Modulation of the hormonal and transcriptional profiles , including changes related to defense signalling , has been reported in many host plants during AM symbioses .

These changes have been often related to the improved stress tolerance common in mycorrhizal plants .

However , results on the alterations in phytohormones content and their role on the symbiosis are controversial .

Here , an integrative analysis of the response of phylogenetically diverse plants ( i.e. , tomato , soybean , and maize ) to two mycorrhizal fungi -Funneliformis mosseae and Rhizophagus irregularis- was performed .

The analysis of the defense-related hormones salicylic acid , abscisic acid , and jasmonates , and the expression of marker genes of the pathways they regulate , revealed significant changes in the roots of mycorrhizal plants .

These changes depended on both the plant and the AM fungus ( AMF ) involved .

However , general trends can be identified : roots associated with the most effective colonizer R. irregularis showed fewer changes in these defense-related traits , while the colonization by F. mosseae led to significant modifications in all plants tested .

The up-regulation of the jasmonate pathway by F. mosseae was found to be highly conserved among the different plant species , suggesting an important role of jasmonates during this AM interaction .

Our study evidences a strong influence of the AMF genotype on the modulation of host defense signalling , and offers hints on the role of these changes in the symbiosis .


The synthesis of proteinase inhibitor proteins in response to wounding is a defensive response against pest and pathogen attacks .

Wounding of leaves results in the release of a mobile wound signal which induces proteinase inhibitor synthesis throughout the plant .

The signal transduction pathway regulating this response is not fully understood , but several compounds have been identified which are capable of inducing proteinase inhibitor synthesis in tomato and potato leaves .

These compounds include cell wall fragments of both plant and pathogen origin [ 1 - 3 ] , abscisic acid [ 4 ] , jasmonic acid [ 5 ] and , most recently , an 18-amino-acid polypeptide , called systemin , isolated from tomato leaves [ 6 ] .

In this chapter , we describe the properties of systemin and its precursor prosystemin , and we summarize the evidence supporting a role for systemin as an initial signal that regulates proteinase inhibitor synthesis in response to wounding .


We studied the localization of 6-phosphogluconate dehydrogenase ( PGD ) isoforms of Arabidopsis ( Arabidopsis thaliana ) .

Similar polypeptide lengths of PGD1 , PGD2 , and PGD3 obscured which isoform may represent the cytosolic and/or plastidic enzyme plus whether PGD2 with a peroxisomal targeting motif also might target plastids .

Reporter-fusion analyses in protoplasts revealed that , with a free N terminus , PGD1 and PGD3 accumulate in the cytosol and chloroplasts , whereas PGD2 remains in the cytosol .

Mutagenesis of a conserved second ATG enhanced the plastidic localization of PGD1 and PGD3 but not PGD2 .

Amino-terminal deletions of PGD2 fusions with a free C terminus resulted in peroxisomal import after dimerization , and PGD2 could be immunodetected in purified peroxisomes .

Repeated selfing of pgd2 transfer (T-)DNA alleles yielded no homozygous mutants , although siliques and seeds of heterozygous plants developed normally .

Detailed analyses of the C-terminally truncated PGD2 - 1 protein showed that peroxisomal import and catalytic activity are abolished .

Reciprocal backcrosses of pgd2 - 1 suggested that missing PGD activity in peroxisomes primarily affects the male gametophyte .

Tetrad analyses in the quartet1 - 2 background revealed that pgd2 - 1 pollen is vital and in vitro germination normal , but pollen tube growth inside stylar tissues appeared less directed .

Mutual gametophytic sterility was overcome by complementation with a genomic construct but not with a version lacking the first ATG .

These analyses showed that peroxisomal PGD2 activity is required for guided growth of the male gametophytes and pollen tube-ovule interaction .

Our report finally demonstrates an essential role of oxidative pentose-phosphate pathway reactions in peroxisomes , likely needed to sustain critical levels of nitric oxide and/or jasmonic acid , whose biosynthesis both depend on NADPH provision .


Rising atmospheric CO2 concentrations can affect the induced defense of plants against herbivory by chewing insects , but little is known about whether elevated CO2 can change the inducible defense of plants against herbivory by aphids , which are phloem-sucking rather than tissue-chewing insects .

Interactions between the green peach aphid Myzus persicae and four isogenic Arabidopsis thaliana genotypes including wild type and three induced defense pathway deficient mutants were examined under ambient and elevated CO2 .

Our data showed that elevated CO2 increased the population abundance of peach aphid when reared on wild type and SA-deficient mutant plants .

Regardless of aphid infestation , elevated CO2 decreased the jasmonic acid ( JA ) but increased the salicylic acid ( SA ) level in wild-type plants .

In addition , elevated CO2 increased SA level in SA-deficient mutant while did not change the JA level in JA-deficient mutant .

Pathway enrichment analysis based on high-throughput transcriptome sequencing suggested that CO2 level , aphid infestation , and their interactions ( respectively ) altered plant defense pathways .

Furthermore , qPCR results showed that elevated CO2 up-regulated the expression of SA-dependent defense genes but down-regulated the expression of JA/ethylene-dependent defense genes in wild-type plants infested by aphids .

The current study indicated that elevated CO2 tended to enhance the ineffective defense-SA signaling pathway and to reduce the effective defense-JA signaling pathway against aphids , which resulted in increased aphid numbers .


Plastids are the central orchestrators of the early and late responses to wounding and herbivory in plants .

This organelle houses some of the most important enzymes involved in the biogenesis of intra and extracellular signals that mediate defense responses against these stresses .

Among these enzymes are the ones initiating the biosynthesis of oxylipins [ e.g. , jasmonic acid ( JA ) and C(6 ) volatiles ] , terpenoid volatiles and phenolic compounds , including both volatile [ e.g. , methylsalicylate ( MeSA ) ] and non-volatile compounds [ e.g. , salicylic acid ( SA ) ] .

Plastids also play a major role in orchestrating changes in primary metabolism during herbivory and thereby in the reallocation of carbon and nitrogen to different functions in response to herbivory .

How the primary stress signals generated by mechanical damage and herbivory reach the plastid to activate the rapid synthesis of these signal molecules is at present largely unknown .