Autophagy is an evolutionarily conserved intracellular process for vacuolar degradation of cytoplasmic components .

In higher plants , autophagy defects result in early senescence and excessive immunity-related programmed cell death ( PCD ) irrespective of nutrient conditions ; however , the mechanisms by which cells die in the absence of autophagy have been unclear .

Here , we demonstrate a conserved requirement for salicylic acid ( SA ) signaling for these phenomena in autophagy-defective mutants ( atg mutants ) .

The atg mutant phenotypes of accelerated PCD in senescence and immunity are SA signaling dependent but do not require intact jasmonic acid or ethylene signaling pathways .

Application of an SA agonist induces the senescence/cell death phenotype in SA-deficient atg mutants but not in atg npr1 plants , suggesting that the cell death phenotypes in the atg mutants are dependent on the SA signal transducer NONEXPRESSOR OF PATHOGENESIS-RELATED GENES1 .

We also show that autophagy is induced by the SA agonist .

These findings imply that plant autophagy operates a novel negative feedback loop modulating SA signaling to negatively regulate senescence and immunity-related PCD .


BACKGROUND AND AIMS : Rhizomes are underground stems with meristematic tissues capable of generating shoots and roots .

However , mechanisms controlling rhizome formation and growth are yet to be completely understood .

The objectives of this study were to investigate whether rhizome development could be regulated by cytokinins ( CKs ) and gibberellic acids ( GAs ) , and determine underlying mechanisms of regulation of rhizome formation and growth of tall fescue ( Festuca arundinacea ) by a CK or GA through proteomic and transcript analysis .

METHODS : A rhizomatous genotype of tall fescue ( ' BR ' ) plants were treated with 6-benzylaminopurine ( BAP , a synthetic cytokinin ) or GA3 in hydroponic culture in growth chambers .

Furthermore , comparative proteomic analysis of two-dimensional electrophoresis and mass spectrometry were performed to investigate proteins and associated metabolic pathways imparting increased rhizome number by BAP and rhizome elongation by GA3 KEY RESULTS : BAP stimulated rhizome formation while GA3 promoted rhizome elongation .

Proteomic analysis identified 76 differentially expressed proteins ( DEPs ) due to BAP treatment and 37 DEPs due to GA3 treatment .

Cytokinin-related genes and cell division-related genes were upregulated in the rhizome node by BAP and gibberellin-related and cell growth-related genes in the rhizome by GA3 CONCLUSIONS : Most of the BAP- or GA-responsive DEPs were involved in respiratory metabolism and amino acid metabolism .

Transcription analysis demonstrated that genes involved in hormone metabolism , signalling pathways , cell division and cell-wall loosening were upregulated by BAP or GA3 The CK and GA promoted rhizome formation and growth , respectively , by activating metabolic pathways that supply energy and amino acids to support cell division and expansion during rhizome initiation and elongation in tall fescue .


Menthol mint ( Mentha arvensis L. ) cultivation is significantly affected by the heavy metals like cadmium ( Cd ) which also imposes severe health hazards .

Two menthol mint cultivars namely Kosi and Kushal were evaluated under Cd stress conditions .

Impact of plant growth regulators ( PGRs ) like salicylic acid ( SA ) , gibberellic acid ( GA(3 ) ) and triacontanol ( Tria ) on Cd stress tolerance was assessed .

Reduced growth , photosynthetic parameters , mineral nutrient concentration , and increased oxidative stress biomarkers like electrolyte leakage , malondialdehyde , and hydrogen peroxide contents were observed under Cd stress .

Differential upregulation of proline content and antioxidant activities under Cd stress was observed in both the cultivars .

Interestingly , low electrolyte leakage , lipid peroxidation , hydrogen peroxide and Cd concentration in leaves were observed in Kushal compared to Kosi .

Among all the PGRs tested , SA proved to be the best in improving Cd-stress tolerance in both the cultivars but Kushal responded better than Kosi .


BACKGROUND : Rare data are available on the molecular responses of higher plants to low pH. Seedlings of ' Sour pummelo ' ( Citrus grandis ) and ' Xuegan ' ( Citrus sinensis ) were treated daily with nutrient solution at a pH of 2.5 , 3 , or 6 ( control ) for nine months .

Thereafter , we first used 2-dimensional electrophoresis ( 2-DE ) to investigate low pH-responsive proteins in Citrus leaves .

Meanwhile , we examined low pH-effects on leaf gas exchange , carbohydrates , ascorbate , dehydroascorbate and malondialdehyde .

The objectives were to understand the adaptive mechanisms of Citrus to low pH and to identify the possible candidate proteins for low pH-tolerance .

RESULTS : Our results demonstrated that Citrus were tolerant to low pH , with a slightly higher low pH-tolerance in the C. sinensis than in the C. grandis .

Using 2-DE , we identified more pH 2.5-responsive proteins than pH 3-responsive proteins in leaves .

This paper discussed mainly on the pH 2.5-responsive proteins .

pH 2.5 decreased the abundances of proteins involved in ribulose bisphosphate carboxylase/oxygenase activation , Calvin cycle , carbon fixation , chlorophyll biosynthesis and electron transport , hence lowering chlorophyll level , electron transport rate and photosynthesis .

The higher oxidative damage in the pH 2.5-treated C. grandis leaves might be due to a combination of factors including higher production of reactive oxygen species , more proteins decreased in abundance involved in antioxidation and detoxification , and lower ascorbate level .

Protein and amino acid metabolisms were less affected in the C. sinensis leaves than those in the C. grandis leaves when exposed to pH 2.5 .

The abundances of proteins related to jasmonic acid biosynthesis and signal transduction were increased and decreased in the pH 2.5-treated C. sinensis and C. grandis leaves , respectively .

CONCLUSIONS : This is the first report on low pH-responsive proteins in higher plants .

Thus , our results provide some novel information on low pH-toxicity and -tolerance in higher plants .


Nonspecific lipid transfer proteins ( nsLTPs ) are small , basic cystein-rich proteins believed to be involved in plant defense mechanisms .

Three cDNAs coding nsLTPs from grape ( Vitis vinifera sp. ) were cloned by reverse-transcriptase-polymerase chain reaction ( RT-PCR ) and PCR .

The expression of nsLTP genes was investigated in 41B-rootstock grape cell suspension , in response to various defense-related signal molecules .

Ergosterol ( a fungi-specific sterol ) and a proteinaceous elicitor purified from Botrytis cinerea strongly and rapidly induced the accumulation of nsLTP mRNAs .

Jasmonic acid , cholesterol , and sitosterol also promoted nsLTPs mRNA accumulation , although to a lesser extent , whereas salicylic acid had no effect .

High performance liquid chromatography analysis indicated that the amounts of three LTP isoforms ( previously named P1 , P2 , and P4 ) were increased by ergosterol .

None of the four isoforms displayed any significant antifungal properties , with the exception of the P4 isoform , which reduced Botrytis mycelium growth in vitro , but only in calcium-free medium .

The results are discussed in the context of plant-pathogen interactions .


We analyzed expression of marker genes for three defense pathways during infection by Cauliflower mosaic virus ( CaMV ) , a compatible pathogen of Arabidopsis ( Arabidopsis thaliana ) , using luciferase reporter transgenes and directly by measuring transcript abundance .

Expression of PR-1 , a marker for salicylic acid signaling , was very low until 8 d postinoculation and then rose sharply , coinciding with the rise in virus levels .

In contrast , as early as 2 h postinoculation , transcriptional up-regulation of GST1-a marker for reactive oxygen species-and PDF1.2-a marker for jasmonic acid/ethylene defense signaling-was detectable in the virus-inoculated leaf and systemically . In parallel with the activation of GST1 , H(2)O(2 ) accumulated locally and systemically in virus- but not mock-inoculated plants .

However , in plants inoculated with infectious CaMV DNA rather than virus particles , the onset of systemic luciferase activity was delayed by 24 to 48 h , suggesting that virion structural proteins act as the elicitor .

This phenomenon , which we term the rapid systemic response , preceded virus movement from the inoculated leaf ; therefore , the systemic signal is not viral .

Systemic , but not local , H(2)O(2 ) accumulation was abolished in rbohDF double mutants and in etr1 - 1 and ein2 - 1 mutants , implicating NADPH oxidase and ethylene signaling in the generation and transduction of the response .

Ethylene , but not rbohDF mutants , also showed reduced susceptibility to CaMV , whereas in NahG transgenics , virus levels were similar to wild type .

These findings implicate reactive oxygen species and ethylene in signaling in response to CaMV infection , but suggest that salicylic acid does not play an effective role .


The present study was aimed to investigate the effects of subacute and subchronic treatment of some plant growth regulators ( PGRs ) , such as abscisic acid ( ABA ) and gibberellic acid ( GA3 ) , on neurological and immunological biomarkers in various tissues of rats .

The activities of acetylcholinesterase ( AChE ) and butrylcholinesterase ( BChE ) were selected as biomarkers for neurotoxic biomarkers .

Adenosine deaminase ( ADA ) and myeloperoxidase ( MPO ) were measured as indicators for immunotoxic investigation purpose .

Wistar albino rats were orally administered with 25 and 50 ppm of PGRs ad libitum for 25 - 50 days continuously with drinking water .

The treatment of PGRs caused different effects on the activities of enzymes .

Results showed that the administrations of ABA and GA3 increased AChE and BChE activities in some tissues of rats treated with both the dosages and periods of ABA and GA3 .

With regard to the immunotoxic effects , ADA activity fluctuated , while MPO activity increased after subacute and subchronic exposure of treated rat tissues to both dosages when compared with the controls .

The observations presented led us to conclude that the administrations of PGRs at subacute and subchronic exposure increased AChE , BChE , and MPO activities , while fluctuating the ADA activity in various tissues of rats .

This may reflect the potential role of these parameters as useful biomarkers for toxicity of PGRs .


Jasmonates control defense gene expression and male fertility in the model plant Arabidopsis thaliana .

In both cases , the involvement of the jasmonate pathway is complex , involving large-scale transcriptional reprogramming .

Additionally , jasmonate signaling is hard-wired into the auxin , ethylene , and salicylate signal networks , all of which are under intense investigation in Arabidopsis .

In male fertility , jasmonic acid ( JA ) is the essential signal intervening both at the level of anther elongation and in pollen dehiscense .

A number of genes potentially involved in jasmonate-dependent anther elongation have recently been discovered .

In the case of defense , at least two jasmonates , JA and its precursor 12-oxo-phytodienoic acid ( OPDA ) , are necessary for the fine-tuning of defense gene expression in response to various microbial pathogens and arthropod herbivores .

However , only OPDA is required for full resistance to some insects and fungi .

Other jasmonates probably affect yet more physiological responses .

A series of breakthroughs have identified the SKP/CULLIN/F-BOX ( SCF ) , CORONATINE INSENSITIVE ( COI1 ) complex , acting together with the CONSTITUTIVE PHOTOMORPHOGENIC 9 ( COP9 ) signalosome , as central regulatory components of jasmonate signaling in Arabidopsis .

The studies , mostly involving mutational approaches , have paved the way for suppressor screens that are expected to further extend our knowledge of jasmonate signaling .

When these and other new mutants affecting jasmonate signaling are characterized , new nodes will be added to the Arabidopsis Jasmonate Signaling Pathway Connections Map , and the lists of target genes regulated by jasmonates in Arabidopsis will be expanded .


The large WRKY transcription factor family is mainly involved in regulating plant immune responses .

Arabidopsis WRKY33 is a key transcriptional regulator of hormonal and metabolic processes towards Botrytis cinerea strain 2100 infection and is essential for resistance .

In contrast to B. cinerea strain 2100 , the strain B05.10 is virulent on wild-type ( WT ) Col-0 Arabidopsis plants highlighting the genetic diversity within this pathogen species .

We analysed how early WRKY33-dependent responses are affected upon infection with strain B05.10 and found that most of these responses were strongly dampened during this interaction .

Ectopic expression of WRKY33 resulted in complete resistance towards this strain indicating that virulence of B05.10 , at least partly , depends on suppressing WRKY33 expression/protein accumulation .

As a consequence , the expression levels of direct WRKY33 target genes , including those involved in the biosynthesis of camalexin , were also reduced upon infection .

Concomitantly , elevated levels of the phytohormone abscisic acid ( ABA ) were observed .

Molecular and genetic studies revealed that ABA negatively influences defence to B05.10 and effects jasmonic acid/ethylene ( JA/ET ) and salicylic acid ( SA ) levels .

Susceptibility/resistance was determined by the antagonistic effect of ABA on JA , and this crosstalk required suppressing WRKY33 functions at early infection stages .

This indicates that B. cinerea B05.10 promotes disease by suppressing WRKY33-mediated host defences .


Bowman-Birk inhibitor ( BBI ) genes encode serine protease inhibitors well known for their anticarcinogenic properties and roles in plant defense against insects and pathogens .

Here we investigated the expression of a BBI gene in response to water deficit , recovery and phytohormones .

A full length cDNA encoding a novel BBI ( AhBBI ) was isolated from peanut ( Arachis hypogaea L. ) leaves .

The deduced protein is a polypeptide of 11.5kDa containing a signal peptide of 20 amino acids which is missing from peanut seed full-length BBI .

Sequence analysis showed that AhBBI presents the characteristic features of BBIs but its first inhibitory loop is unique among the Fabaceae species .

Real-time PCR analyses indicated that in peanut leaves , AhBBI is upregulated by water deficit and exogenous jasmonic acid ( JA ) but repressed by abscissic acid ( ABA ) after 24h of treatment .

The transcripts accumulation patterns during water deficit differed between two cultivars studied in relation to their tolerance levels to drought .

AhBBI transcripts accumulated earlier and stronger in the tolerant cultivar ( cv . Fleur11 ) compared to the susceptible one ( cv . 73 - 30 ) suggesting that BBI genes are involved in drought stress tolerance .

Subsequent rehydration reversed the accumulation of AhBBI transcripts in both cultivars but at different levels .

The overall role of BBI in abiotic stress tolerance and the possible mechanisms of action are discussed .


Apoplast , the diffusional space between plant cell plasma membranes , is an important medium for signaling within and between the cells .

Apoplastic reactive oxygen species ( ROS ) are crucial signaling molecules in various biological processes .

ROS signaling is interconnected with the response to several hormones , including jasmonic acid ( JA ) , salicylic acid ( SA ) and ethylene .

Using ozone ( O3 ) to activate apoplastic ROS signaling , we performed global and targeted analysis of transcriptional changes and cell death assays to dissect the contribution of hormone signaling and various transcription factors ( TFs ) in the regulation of gene expression and cell death .

The contributions of SA , JA , and ethylene were assessed through analysis of single , double , and triple mutants deficient in biosynthesis or signaling for all three hormones .

Even in the triple mutant , the global gene expression responses to O3 were mostly similar to the wild-type .

Cell death in the JA receptor mutant coi1 - 16 was suppressed by impairment of the NADPH oxidase RBOHF , suggesting a role for a ROS signal in limiting the spread of cell death .

In response to apoplastic ROS , there is not a single signaling pathway that regulates gene expression or cell death .

Instead , several pathways regulate the apoplastic ROS response via combinatorial or overlapping mechanisms .


BACKGROUND : Salt stress is a devastating environmental stress that causes plant growth inhibition and yield reduction .

OBJECTIVE : The identification of salt-tolerant genes brings hope for the generation of salinity-tolerant crop plants through molecular breeding .

METHODS : In this study , one salt-sensitive and one salt-tolerant maize inbred line were screened from 242 maize inbred lines .

Reactive oxygen species (ROS)-related enzyme activities were detected and salt-responsive comparative transcriptome analysis was performed for control and 220 mM NaCl treated maize leaves .

RESULTS : Salt-tolerant maize inbred line ( L87 ) showed higher ROS-related enzyme ( SOD , POD , APX and CAT ) activities and accumulated relatively lower levels of ROS under salt stress .

Of the total DEGs , 1856 upregulated DEGs were specific to L87 , including stress tolerance-related members of the 70kDa family of heat shock proteins ( Hsp70s ) and aquaporins .

The DEGs involved in the abscisic acid ( ABA ) , ethylene , jasmonic acid ( JA ) and salicylic acid ( SA ) signal transduction pathways may determine the difference in salt tolerance between the two varieties , especially one central component SnRK2 , that positively regulates ABA signaling and was only upregulated in L87 .

Analysis of DEGs related to ROS scavenging showed that some peroxidase ( POD ) , glutathione S-transferase ( GST ) , catalase ( CAT ) and superoxide dismutase ( SOD ) genes specific to L87 probably enhanced its salt tolerance .

The analysis of differentially expressed transcription factors ( TFs ) suggested that WRKY TFs could contribute to the difference in salt tolerance between the two maize lines .

CONCLUSION : Compared with Salt-sensitive maize inbred line ( L29 ) , L87 exhibits specific regulatory mechanisms related to salt tolerance , including plant hormone interactions , ROS scavenging and the regulation of TFs .

Our study identifies new candidate genes that may regulate maize tolerance to salt stress and provides useful information for breeding maize with high salt resistance .


The cyclic derivative of 13(S)-hydroperoxolinolenic acid , 12-oxophytodienoic acid , serves as a signal transducer in higher plants , mediating mechanotransductory processes and plant defenses against a variety of pathogens , and also serves as a precursor for the biosynthesis of jasmonic acid , a mediator of plant herbivore defense .

Biosynthesis of 12-oxophytodienoic acid from alpha-linolenic acid occurs in plastids , mainly in chloroplasts , and is thought to start with free linolenic acid liberated from membrane lipids by lipase action .

In Arabidopsis thaliana , the glycerolipid fraction contains esterified 12-oxophytodienoic acid , which can be released enzymatically by sn1-specific , but not by sn2-specific , lipases .

The 12-oxophytodienoyl glycerolipid fraction was isolated , purified , and characterized .

The novel class of lipids is localized in plastids .

Purified monogalactosyl diglyceride was not converted to the sn1-(12-oxophytodienoyl ) derivative by the combined action of ( soybean ) lipoxygenase and ( A. thaliana ) allene oxide synthase , an enzyme ensemble that converts free alpha-linolenic acid to free 12-oxophytodienoic acid .

When leaves were wounded , a significant and transient increase in the level of (12-oxophytodienoyl)-monogalactosyl diglyceride was observed .

In A. thaliana , the major fraction of 12-oxophytodienoic acid occurs esterified at the sn1 position of the plastid-specific glycerolipid , monogalactosyl diglyceride .


The rice pathogenesis-related protein OsPR10a was scarcely expressed in OsCDPK1-silenced ( Ri-1 ) rice , which was highly sensitive to pathogen infection .

After inoculating the leaves with bacterial blight ( Xanthomonas oryzae pv . oryzae ; Xoo ) , we found that the expression of OsPR10a was up- and down-regulated in OEtr-1 ( overexpression of the constitutively active truncated form of OsCDPK1 ) and Ri-1 rice plants , respectively .

OsPR10a and OsCDPK1 showed corresponding expression patterns and were up-regulated in response to the jasmonic acid , salicylic acid and Xoo treatments , and OsPR1 and OsPR4 were significantly up-regulated in OEtr-1 .

These results suggest that OsCDPK1 may be an upstream regulator involved in rice innate immunity and conferred broad-spectrum of disease resistance .

Following the Xoo inoculation , the OEtr-1 and Ri-1 seedlings showed enhanced and reduced disease resistance , respectively .

The dihybrid rice Ri-1/OsPR10a-Ox not only bypassed the effect of OsCDPK1 silencing on the susceptibility to Xoo but also showed enhanced disease resistance and , consistent with Ri-1 phenotypes , increased plant height and grain size .

Our results reveal that OsCDPK1 plays novel key roles in the cross-talk and mediation of the balance between stress response and development and provides a clue for improving grain yield and disease resistance simultaneously in rice .


Gibberellic acid (GA)-mediated cell expansion initiates the seed-to-seedling transition in plants and is repressed by DELLA proteins .

Using digital single-cell analysis , we identified a cellular subdomain within the midhypocotyl , whose expansion drives the final step of this developmental transition under optimal conditions .

Using network inference , the transcription factor ATHB5 was identified as a genetic factor whose localized expression promotes GA-mediated expansion specifically within these cells .

Both this protein and its putative growth-promoting target EXPANSIN3 are repressed by DELLA , and coregulated at single-cell resolution during seed germination .

The cellular domains of hormone sensitivity were explored within the Arabidopsis ( Arabidopsis thaliana ) embryo by putting seeds under GA-limiting conditions and quantifying cellular growth responses .

The middle and upper hypocotyl have a greater requirement for GA to promote cell expansion than the lower embryo axis .

Under these conditions , germination was still completed following enhanced growth within the radicle and lower axis .

Under GA-limiting conditions , the athb5 mutant did not show a phenotype at the level of seed germination , but it did at a cellular level with reduced cell expansion in the hypocotyl relative to the wild type .

These data reveal that the spatiotemporal cell expansion events driving this transition are not determinate , and the conditional use of GA-ATHB5-mediated hypocotyl growth under optimal conditions may be used to optionally support rapid seedling growth .

This study demonstrates that multiple genetic and spatiotemporal cell expansion mechanisms underlie the seed to seedling transition in Arabidopsis .


Plants respond to stresses by producing a broad spectrum of bioactive specialized metabolites .

Hormonal elicitors , such as jasmonates , trigger a complex signaling circuit leading to the concerted activation of specific metabolic pathways .

However , for many specialized metabolic pathways , the transcription factors involved remain unknown .

Here , we report on two homologous jasmonate-inducible transcription factors of the basic helix-loop-helix family , TRITERPENE SAPONIN BIOSYNTHESIS ACTIVATING REGULATOR1 ( TSAR1 ) and TSAR2 , which direct triterpene saponin biosynthesis in Medicago truncatula .

TSAR1 and TSAR2 are coregulated with and transactivate the genes encoding 3-HYDROXY-3-METHYLGLUTARYL-COENZYME A REDUCTASE1 ( HMGR1 ) and MAKIBISHI1 , the rate-limiting enzyme for triterpene biosynthesis and an E3 ubiquitin ligase that controls HMGR1 levels , respectively .

Transactivation is mediated by direct binding of TSARs to the N-box in the promoter of HMGR1 .

In transient expression assays in tobacco ( Nicotiana tabacum ) protoplasts , TSAR1 and TSAR2 exhibit different patterns of transactivation of downstream triterpene saponin biosynthetic genes , hinting at distinct functionalities within the regulation of the pathway .

Correspondingly , overexpression of TSAR1 or TSAR2 in M. truncatula hairy roots resulted in elevated transcript levels of known triterpene saponin biosynthetic genes and strongly increased the accumulation of triterpene saponins .

TSAR2 overexpression specifically boosted hemolytic saponin biosynthesis , whereas TSAR1 overexpression primarily stimulated nonhemolytic soyasaponin biosynthesis .

Both TSARs also activated all genes of the precursor mevalonate pathway but did not affect sterol biosynthetic genes , pointing to their specific role as regulators of specialized triterpene metabolism in M. truncatula .


Thellungiella , an Arabidopsis ( Arabidopsis thaliana)-related halophyte , is an emerging model species for studies designed to elucidate molecular mechanisms of abiotic stress tolerance .

Using a cDNA microarray containing 3,628 unique sequences derived from previously described libraries of stress-induced cDNAs of the Yukon ecotype of Thellungiella salsuginea , we obtained transcript profiles of its response to cold , salinity , simulated drought , and rewatering after simulated drought .

A total of 154 transcripts were differentially regulated under the conditions studied .

Only six of these genes responded to all three stresses of drought , cold , and salinity , indicating a divergence among the end responses triggered by each of these stresses .

Unlike in Arabidopsis , there were relatively few transcript changes in response to high salinity in this halophyte .

Furthermore , the gene products represented among drought-responsive transcripts in Thellungiella associate a down-regulation of defense-related transcripts with exposure to water deficits .

This antagonistic interaction between drought and biotic stress response may demonstrate Thellungiella 's ability to respond precisely to environmental stresses , thereby conserving energy and resources and maximizing its survival potential .

Intriguingly , changes of transcript abundance in response to cold implicate the involvement of jasmonic acid .

While transcripts associated with photosynthetic processes were repressed by cold , physiological responses in plants developed at low temperature suggest a novel mechanism for photosynthetic acclimation .

Taken together , our results provide useful starting points for more in-depth analyses of Thellungiella 's extreme stress tolerance .


The hormone jasmonate ( JA ) , which functions in plant immunity , regulates resistance to pathogen infection and insect attack through triggering genome-wide transcriptional reprogramming in plants .

We show that the basic helix-loop-helix transcription factor ( TF ) MYC2 in tomato ( Solanum lycopersicum ) acts downstream of the JA receptor to orchestrate JA-mediated activation of both the wounding and pathogen responses .

Using chromatin immunoprecipitation sequencing ( ChIP-seq ) coupled with RNA sequencing ( RNA-seq ) assays , we identified 655 MYC2-targeted JA-responsive genes .

These genes are highly enriched in Gene Ontology categories related to TFs and the early response to JA , indicating that MYC2 functions at a high hierarchical level to regulate JA-mediated gene transcription .

We also identified a group of MYC2-targeted TFs ( MTFs ) that may directly regulate the JA-induced transcription of late defense genes .

Our findings suggest that MYC2 and its downstream MTFs form a hierarchical transcriptional cascade during JA-mediated plant immunity that initiates and amplifies transcriptional output .

As proof of concept , we showed that during plant resistance to the necrotrophic pathogen Botrytis cinerea , MYC2 and the MTF JA2-Like form a transcription module that preferentially regulates wounding-responsive genes , whereas MYC2 and the MTF ETHYLENE RESPONSE FACTOR.C3 form a transcription module that preferentially regulates pathogen-responsive genes .


Ozone layer depletion leads to elevated ultraviolet-B ( UV-B ) radiation , which affects plant growth ; however , little is known about the relationship between root growth and signaling molecules in roots .

Therefore , in this work , simulated UV-B radiation was used to study the effects of elevated UV-B radiation on root growth of soybean seedlings and changes in the content of signaling molecules in roots .

The results showed that compared with the control , the 2.63 kJ m(-2 ) d(-1 ) and 6.17 kJ m(-2 ) d(-1 ) elevated UV-B radiation treatments inhibited root growth , and root growth parameters ( total root length , root surface area , root volume , average diameter , root tip number , and root dry weight ) all decreased .

For root signaling molecules , the content of nitric oxide , reactive oxygen species , abscisic acid , salicylic acid , and jasmonic acid increased , and the content of auxin , cytokinin , and gibberellin decreased .

The above indices changed more significantly under the 6.17 kJ m(-2 ) d(-1 ) treatment .

After withdrawal of the exposure , the above indices could be restored to a certain extent .

These data indicated that UV-B radiation interfered with root growth by affecting the content of signaling molecules in roots , and the degree of the effects was related to the intensity of UV-B radiation .

The results from this study provide a theoretical basis for studying the preliminary mechanism of elevated UV-B radiation on root growth and possible pathways that can mitigate UV-B radiation damage for root growth .

ONE SENTENCE SUMMARY : The effects of elevated UV-B on root growth of soybean seedlings were regulated by signaling molecules , and the degree of the effects was related to the intensity of UV-B radiation .


BACKGROUND : Plants respond to various stress stimuli by activating an enhanced broad-spectrum defensive ability .

The development of novel resistance inducers represents an attractive , alternative crop protection strategy .

In this regard , hexanoic acid ( Hxa , a chemical elicitor ) and azelaic acid ( Aza , a natural signaling compound ) have been proposed as inducers of plant defense , by means of a priming mechanism .

Here , we investigated both the mode of action and the complementarity of Aza and Hxa as priming agents in Nicotiana tabacum cells in support of enhanced defense .

RESULTS : Metabolomic analyses identified signatory biomarkers involved in the establishment of a pre-conditioned state following Aza and Hxa treatment .

Both inducers affected the metabolomes in a similar manner and generated common biomarkers : caffeoylputrescine glycoside , cis-5-caffeoylquinic acid , feruloylglycoside , feruloyl-3-methoxytyramine glycoside and feruloyl-3-methoxytyramine conjugate .

Subsequently , quantitative real time-PCR was used to investigate the expression of inducible defense response genes : phenylalanine ammonia lyase , hydroxycinnamoyl CoA quinate transferase and hydroxycinnamoyl transferase to monitor activation of the early phenylpropanoid pathway and chlorogenic acids metabolism , while ethylene response element-binding protein , small sar1 GTPase , heat shock protein 90 , RAR1 , SGT1 , non-expressor of PR genes 1 and thioredoxin were analyzed to report on signal transduction events .

Pathogenesis-related protein 1a and defensin were quantified to investigate the activation of defenses regulated by salicylic acid and jasmonic acid respectively .

The qPCR results revealed differential expression kinetics and , in general ( except for NPR1 , Thionin and PR1a ) , the relative gene expression ratios observed in the Hxa-treated cells were significantly greater than the expression observed in the cells treated with Aza .

CONCLUSIONS : The results indicate that Aza and Hxa have a similar priming effect through activation of genes involved in the establishment of systemic acquired resistance , associated with enhanced synthesis of hydroxycinnamic acids and related conjugates .


Plants under stress from both biotic and abiotic sources produce increased levels of ethylene , which is perceived by ethylene receptors and triggers cellular responses further downstream .

Protein phosphorylation and dephosphorylation were implicated in the regulation of ethylene induction by stresses based on studies using protein kinase and phosphatase inhibitors .

However , the kinase(s ) involved remains to be determined .

Using a conditional gain-of-function transgenic system , we demonstrate that the activation of SIPK , a tobacco mitogen-activated protein kinase ( MAPK ) , by NtMEK2DD , an active mutant of the upstream kinase of SIPK , resulted in a dramatic increase in ethylene production .

The increase in ethylene after the activation of SIPK coincided with a dramatic increase in 1-aminocyclopropane-1-carboxylic acid ( ACC ) synthase ( ACS ) activity , which was followed by the activation of a subgroup of ACS and ACC oxidase ( ACO ) genes , suggesting that either the activation of unidentified ACS(s ) or post-transcriptional regulation is involved .

Infection with Tobacco mosaic virus ( TMV ) , which is known to activate the SIPK cascade and induce ethylene biosynthesis , also induced the same ACSs and ACOs .

After ethylene production in NtMEK2DD plants , strong activation of ETHYLENE-RESPONSE FACTOR ( ERF ) genes was observed , similar to the effect in NN tobacco plants infected with TMV .

In contrast to previous reports , no major increase in jasmonic acid ( JA ) and methyl jasmonate ( MJ ) was detected after the activation of SIPK/WIPK in NtMEK2DD transgenic plants .

These results suggest that the induction of ethylene but not JA/MJ is involved in plant defense responses mediated by the NtMEK2-SIPK/WIPK pathway .


The effects of phytohormones ( abscisic acid , gibberelic acid , and jasmonic acid ) and ambiol ( a synthetic growth regulator ) on processes of H+ transport across the plasmalemma were studied in membrane vesicles isolated from the parenchyma of potato ( Solanum tuberosum L. ) tubers .

Phytohormones and ambiol were tested either individually or in combinations .

Each of the substances tested changed the initial rate of H+ uptake by the vesicles .

Two signaling substances added to the incubation medium simultaneously modified the activity of each other .

It is suggested that the interaction of a signaling substance with components of the plasmalemma alters the responses of the membrane to other signaling molecules .


The necrotrophic fungus Botrytis cinerea causes devastating pre- and post-harvest yield losses in grapevine ( Vitis vinifera L. ) .

Although B. cinerea has been well-studied in different plant species , there is limited information related to the resistance and susceptibility mechanisms of Vitis genotypes against B. cinerea infection .

In the present study , leaves and berries of twenty four grape genotypes were evaluated against B. cinerea infection .

According to the results , one genotype ( Ju mei gui ) was highly resistant ( HR ) , one genotype ( Kyoho ) was resistant ( R ) , eight genotypes were susceptible ( S ) , and fourteen genotypes were highly susceptible ( HS ) against infection of B. cinerea in leaves .

Whereas in the case of B. cinerea infection in grape berry , three genotypes were found to be highly resistant , three resistant , eleven genotypes susceptible , and seven were highly susceptible .

To further explore the mechanism of disease resistance in grapevine , we evaluated " Ju mei gui " and " Summer black " in terms of B. cinerea progression , reactive oxygen species reactions , jasmonic acid contents , and the activities of antioxidant enzymes in leaf and fruit .

We surmise that the resistance of " Ju mei gui " is due to seized fungal growth , minor reactive oxygen species ( ROS ) production , elevated antioxidant enzyme activity , and more jasmonic acid ( JA ) contents .

This study provides insights into the resistance and susceptibility mechanism of Vitis genotypes against B. cinerea .

This will help for the selection of appropriate germplasm to explore the molecular basis of disease resistance mechanisms in grapevine .


• Arsenic ( As ) contamination of rice ( Oryza sativa ) is a worldwide concern and elucidating the molecular mechanisms of As accumulation in rice may provide promising solutions to the problem .

Previous studies using microarray techniques to investigate transcriptional regulation of plant responses to As stress have identified numerous differentially expressed genes .

However , little is known about the metabolic and regulatory network remodelings , or their interactions with microRNA ( miRNA ) in plants upon As(III ) exposure .

• We used Illumina sequencing to acquire global transcriptome alterations and miRNA regulation in rice under As(III ) treatments of varying lengths of time and dosages .

• We found that the response of roots was more distinct when the dosage was varied , whereas that of shoots was more distinct when the treatment time was varied .

In particular , the genes involved in heavy metal transportation , jasmonate ( JA ) biosynthesis and signaling , and lipid metabolism were closely related to responses of rice under As(III ) stress .

Furthermore , we discovered 36 new As(III)-responsive miRNAs , 14 of which were likely involved in regulating gene expression in transportation , signaling , and metabolism .

• Our findings highlight the significance of JA signaling and lipid metabolism in response to As(III ) stress and their regulation by miRNA , which provides a foundation for subsequent functional research .


BACKGROUND : Fusarium head blight ( FHB ) caused by Fusarium species like F. graminearum is a devastating disease of wheat ( Triticum aestivum ) worldwide .

Mycotoxins such as deoxynivalenol produced by the fungus affect plant and animal health , and cause significant reductions of grain yield and quality .

Resistant varieties are the only effective way to control this disease , but the molecular events leading to FHB resistance are still poorly understood .

Transcriptional profiling was conducted for the winter wheat cultivars Dream ( moderately resistant ) and Lynx ( susceptible ) .

The gene expressions at 32 and 72 h after inoculation with Fusarium were used to trace possible defence mechanisms and associated genes .

A comparative qPCR was carried out for selected genes to analyse the respective expression patterns in the resistant cultivars Dream and Sumai 3 ( Chinese spring wheat ) .

RESULTS : Among 2,169 differentially expressed genes , two putative main defence mechanisms were found in the FHB-resistant Dream cultivar .

Both are defined base on their specific mode of resistance .

A non-specific mechanism was based on several defence genes probably induced by jasmonate and ethylene signalling , including lipid-transfer protein , thionin , defensin and GDSL-like lipase genes .

Additionally , defence-related genes encoding jasmonate-regulated proteins were up-regulated in response to FHB .

Another mechanism based on the targeted suppression of essential Fusarium virulence factors comprising proteases and mycotoxins was found to be an essential , induced defence of general relevance in wheat .

Moreover , similar inductions upon fungal infection were frequently observed among FHB-responsive genes of both mechanisms in the cultivars Dream and Sumai 3 .

CONCLUSIONS : Especially ABC transporter , UDP-glucosyltransferase , protease and protease inhibitor genes associated with the defence mechanism against fungal virulence factors are apparently active in different resistant genetic backgrounds , according to reports on other wheat cultivars and barley .

This was further supported in our qPCR experiments on seven genes originating from this mechanism which revealed similar activities in the resistant cultivars Dream and Sumai 3 .

Finally , the combination of early-stage and steady-state induction was associated with resistance , while transcript induction generally occurred later and temporarily in the susceptible cultivars .

The respective mechanisms are attractive for advanced studies aiming at new resistance and toxin management strategies .


The effect of elicitation with arachidonic and jasmonic acids on the production of phenolic compounds as well as the antioxidant and anti-inflammatory properties of phenolic extracts of wheatgrass was evaluated .

The qualitative and quantitative analysis of phenolic compounds carried out with the UPLC-MS technique indicated that luteolin and apigenin derivatives were the dominant flavonoids , while ferulic acid derivatives and syringic acid were the main components in the phenolic acid fraction in the wheatgrass .

No qualitative changes in the examined phenolic compounds were observed in the case of the control and elicited plants , while there was an increase in the content of some compounds .

The antioxidant activity increased in the elicited samples ( with the exception of reducing power ) and this elevation was partially correlated with the increase in the polyphenol content in the studied plants .

Elicitation with 0.01 µM arachidonic acid also caused improvement of potential anti-inflammatory properties of the wheatgrass .


Exposure of gibberellic acid-treated seedlings of a monoecious cucumber cultivar ; Chipper ' ( Cucumis sativus L. ) to ethylene caused thickening of the hypocotyl , inhibited longitudinal growth , and had no effect on fresh weight .

Downward curvature of cotyledons was increased by the presence of ethylene .

A gynoecious breeding line , ; Gy 3 , ' had thicker hypocotyls and displayed its cotyledons in a more downward position than ; Chipper ' .

Excised hypocotyls of the gynoecious seedlings produced three times as much ethylene as did the monoecious Chipper hypocotyls .

Thus , ethylene may play a role in the regulation of cucumber seedling morphology .


The effects of ethephon as a sugarcane ripener are attributed to ethylene .

However , the role of this phytohormone at the molecular level is unknown .

We performed a transcriptome analysis combined with the evaluation of sucrose metabolism and hormone profiling of sugarcane plants sprayed with ethephon or aminoethoxyvinylglycine ( AVG ) , an ethylene inhibitor , at the onset of ripening .

The differential response between ethephon and AVG on sucrose level and sucrose synthase activity in internodes indicates ethylene as a potential regulator of sink strength .

The correlation between hormone levels and transcriptional changes suggests ethylene as a trigger of multiple hormone signal cascades , with approximately 18 % of differentially expressed genes involved in hormone biosynthesis , metabolism , signalling , and response .

A defence response elicited in leaves favoured salicylic acid over the ethylene/jasmonic acid pathway , while the upper internode was prone to respond to ethylene with strong stimuli on ethylene biosynthesis and signalling genes .

Besides , ethylene acted synergistically with abscisic acid , another ripening factor , and antagonistically with gibberellin and auxin .

We identified potential ethylene target genes and characterized the hormonal status during ripening , providing insights into the action of ethylene at the site of sucrose accumulation .

A molecular model of ethylene interplay with other hormones is proposed .


Effects of α-ketol linolenic acid ( KODA ) application on endogenous abscisic acid ( ABA ) , jasmonic acid ( JA ) , and aromatic volatiles were investigated in ' Kyoho ' grapes ( Vitis labrusca × Vitis vinifera ) infected by a pathogen ( Glomerella cingulata ) .

The expressions of 9-cis-epoxycarotenoid dioxygenase ( VvNCED1 ) , ABA 8'-hydroxylase ( VvCYP707A1 ) , lipoxygenase ( VvLOX ) , and allene oxide synthase ( VvAOS ) were also examined .

The grape berries were dipped in 0.1mM KODA solution before inoculation with the pathogen and stored at 25 ° C for 12 days .

The development of infection was significantly suppressed upon KODA treatment .

Endogenous ABA , JA and phaseic acid ( PA ) were induced in inoculated berries .

KODA application before inoculation increased endogenous ABA , PA and JA through the activation of VvNCED1 , VvCYP707A1 and VvAOS genes , respectively .

In addition , terpenes , methyl salicylate ( Me-SA ) and C6-aldehydes such as (E)-2-hexenal and cis-3-hexenal associated with fungal resistance also increased in KODA-treated berries during storage .

These results suggest that the synergistic effect of JA , ABA , and some aromatic volatiles induced by KODA application may provide resistance to pathogen infection in grape berries .


The induction of alpha-amylase triggered by gibberellic acid in barley embryos is repressed by sugars .

We investigated the effects of glucose on the gibberellin signal transduction pathway to localize the site of interaction of the sugar/hormone signalling pathways .

Our results indicate that glucose represses gibberellin signalling late along this hormone transduction pathway , downstream of transcription of the gibberellin-modulated transcriptional activator ( GAMYB ) needed for alpha-amylase induction .

This result suggests either that glucose repression is transduced by a pathway independent of gibberellin signalling or that repression occurs at the level of GAMYB translation .


Seed germination is antagonistically controlled by the phytohormones gibberellic acid ( GA ) and abscisic acid ( ABA ) .

GA promotes seed germination by enhancing the proteasome-mediated destruction of RGL2 ( for RGA-LIKE2 ) , a key DELLA factor repressing germination .

By contrast , ABA blocks germination by inducing ABI5 ( for ABA-INSENSITIVE5 ) , a basic domain/leucine zipper transcription factor repressing germination .

Decreased GA synthesis leads to an increase in endogenous ABA levels through a stabilized RGL2 , a process that may involve XERICO , a RING-H2 zinc finger factor promoting ABA synthesis .

In turn , increased endogenous ABA synthesis is necessary to elevate not only ABI5 RNA and protein levels but also , critically , those of RGL2 .

Increased ABI5 protein is ultimately responsible for preventing seed germination when GA levels are reduced .

However , overexpression of ABI5 was not sufficient to repress germination , as ABI5 activity requires phosphorylation .

The endogenous ABI5 phosphorylation and inhibition of germination could be recapitulated by the addition of a SnRK2 protein kinase to the ABI5 overexpression line .

In sleepy1 mutant seeds , RGL2 overaccumulates ; germination of these seeds can occur under conditions that produce low ABI5 expression .

These data support the notion that ABI5 acts as the final common repressor of germination in response to changes in ABA and GA levels .


The mitogen-activated protein kinase ( MAPK ) signaling cascade is critical for regulating plant defense systems against various kinds of pathogen and environmental stresses .

One component of this cascade , the MAP kinase kinases ( MAPKK ) , has not yet been shown to be induced in plants following biotic attacks , such as those by insects and fungi .

We describe here a gene coding for a blast ( Magnaporthe grisea)- and insect ( Nilaparvata lugens)-responsive putative MAPK kinase , OmMKK1 ( Oryza minuta MAPKK 1 ) , which was identified in a library of O. minuta expressed sequence tags ( ESTs ) .

Two copies of OmMKK1 are present in the O. minuta genome .

They encode a predicted protein with molecular mass 39 kDa and pI of 6.2 .

Transcript patterns following imbibition of plant hormones such as methyl jasmonic acid ( MeJA ) , ethephone , salicylic acid ( SA ) and abscisic acid ( ABA ) , as well as exposure to methyl viologen ( MV ) , revealed that the expression of OmMKK1 is related to defense response signaling pathways .

A comparative analysis of OmMKK1 and its O. sativa ortholog OsMKK1 showed that both were induced by stress-related hormones and biotic stresses , but that the kinetics of their responses differed despite their high amino acid sequence identity ( 96 % ) .


Salinity is a major environmental factor that constrains soybean yield and grain quality .

Given our past observations using the salt-sensitive soybean ( Glycine max [ L. ] Merr . ) accession C08 on its early responses to salinity and salt-induced transcriptomic modifications , the aim of this study was to assess the lipid profile changes in this cultivar before and after short-term salt stress , and to explore the adaptive mechanisms underpinning lipid homeostasis .

To this end , lipid profiling and proteomic analyses were performed on the leaves of soybean seedlings subjected to salt treatment for 0 , 0.5 , 1 , and 2 h. Our results revealed that short-term salt stress caused dynamic lipid alterations resulting in recycling for both galactolipids and phospholipids .

A comprehensive understanding of membrane lipid adaption following salt treatment was achieved by combining time-dependent lipidomic and proteomic data .

Proteins involved in phosphoinositide synthesis and turnover were upregulated at the onset of salt treatment .

Salinity-induced lipid recycling was shown to enhance jasmonic acid and phosphatidylinositol biosyntheses .

Our study demonstrated that salt stress resulted in a remodeling of membrane lipid composition and an alteration in membrane lipids associated with lipid signaling and metabolism in C08 leaves .


Glomus mosseae , a representative species of Endogonaceae ( Phycomycetes ) able to form vesicular-arbuscular mycorrhiza , was investigated for phytohormone production .

Spores of G. mosseae were axenically germinated in water , and the resultant mycelial growth was assayed by standard procedures for extracting plant hormones from microbial cultures .

Paper partition chromatography and specific bioassays were used to separate and identify plant growth-regulating substances .

The microorganism synthesized at least two gibberellin-like substances , one with R(f ) corresponding in position to authentic gibberellic acid , and four substances with the properties of cytokinins .


BACKGROUND : Seed dormancy is controlled by the physiological or structural properties of a seed and the external conditions .

It is induced as part of the genetic program of seed development and maturation .

Seeds with deep physiological embryo dormancy can be stimulated to germinate by a variety of treatments including cold stratification .

Hormonal imbalance between germination inhibitors ( e.g. abscisic acid ) and growth promoters ( e.g. gibberellins ) is the main cause of seed dormancy breaking .

Differences in the status of hormones would affect expression of genes required for germination .

Proteomics offers the opportunity to examine simultaneous changes and to classify temporal patterns of protein accumulation occurring during seed dormancy breaking and germination .

Analysis of the functions of the identified proteins and the related metabolic pathways , in conjunction with the plant hormones implicated in seed dormancy breaking , would expand our knowledge about this process .

RESULTS : A proteomic approach was used to analyse the mechanism of dormancy breaking in Norway maple seeds caused by cold stratification , and the participation of the abscisic ( ABA ) and gibberellic ( GA ) acids .

Forty-four proteins showing significant changes were identified by mass spectrometry .

Of these , eight spots were identified as water-responsive , 18 spots were ABA- and nine GA-responsive and nine spots were regulated by both hormones .

The classification of proteins showed that most of the proteins associated with dormancy breaking in water were involved in protein destination .

Most of the ABA- and GA-responsive proteins were involved in protein destination and energy metabolism .

CONCLUSION : In this study , ABA was found to mostly down-regulate proteins whereas GA up-regulated proteins abundance .

Most of the changes were observed at the end of stratification in the germinated seeds .

This is the most active period of dormancy breaking when seeds pass from the quiescent state to germination .

Seed dormancy breaking involves proteins of various processes but the proteasome proteins , S-adenosylmethionine synthetase , glycine-rich RNA binding protein , ABI3-interacting protein 1 , EF-2 and adenosylhomocysteinase are of particular importance .

The effect of exogenously applied hormones was not a determining factor for total inhibition ( ABA ) or stimulation ( GA ) of Norway maple seed dormancy breaking and germination but proteomic data has proven these hormones play a role .


BACKGROUND : Drought is a severe environmental stress .

It is estimated that about 50 % of the world rice production is affected mainly by drought .

Apart from conventional breeding strategies to develop drought-tolerant crops , innovative computational approaches may provide insights into the underlying molecular mechanisms of stress response and identify drought-responsive markers .

Here we propose a network-based computational approach involving a meta-analytic study of seven drought-tolerant rice genotypes under drought stress .

RESULTS : Co-expression networks enable large-scale analysis of gene-pair associations and tightly coupled clusters that may represent coordinated biological processes .

Considering differentially expressed genes in the co-expressed modules and supplementing external information such as resistance/tolerance QTLs , transcription factors , network-based topological measures , we identify and prioritize drought-adaptive co-expressed gene modules and potential candidate genes .

Using the candidate genes that are well-represented across the datasets as ' seed ' genes , two drought-specific protein-protein interaction networks ( PPINs ) are constructed with up- and down-regulated genes .

Cluster analysis of the up-regulated PPIN revealed ABA signalling pathway as a central process in drought response with a probable crosstalk with energy metabolic processes .

Tightly coupled gene clusters representing up-regulation of core cellular respiratory processes and enhanced degradation of branched chain amino acids and cell wall metabolism are identified .

Cluster analysis of down-regulated PPIN provides a snapshot of major processes associated with photosynthesis , growth , development and protein synthesis , most of which are shut down during drought .

Differential regulation of phytohormones , e.g. , jasmonic acid , cell wall metabolism , signalling and posttranslational modifications associated with biotic stress are elucidated .

Functional characterization of topologically important , drought-responsive uncharacterized genes that may play a role in important processes such as ABA signalling , calcium signalling , photosynthesis and cell wall metabolism is discussed .

Further transgenic studies on these genes may help in elucidating their biological role under stress conditions .

CONCLUSION : Currently , a large number of resources for rice functional genomics exist which are mostly underutilized by the scientific community .

In this study , a computational approach integrating information from various resources such as gene co-expression networks , protein-protein interactions and pathway-level information is proposed to provide a systems-level view of complex drought-responsive processes across the drought-tolerant genotypes .


BACKGROUND : Plant genes that provide a different response to a similar dehydration stress illustrate the concept of transcriptional ' dehydration stress memory ' .

Pre-exposing a plant to a biotic stress or a stress-signaling hormone may increase transcription from response genes in a future stress , a phenomenon known as ' gene priming ' .

Although known that primed transcription is preceded by accumulation of H3K4me3 marks at primed genes , what mechanism provides for their appearance before the transcription was unclear .

How augmented transcription is achieved , whether/how the two memory phenomena are connected at the transcriptional level , and whether similar molecular and/or epigenetic mechanisms regulate them are fundamental questions about the molecular mechanisms regulating gene expression .

RESULTS : Although the stress hormone jasmonic acid ( JA ) was unable to induce transcription of tested dehydration stress response genes , it strongly potentiated transcription from specific ABA-dependent ' memory ' genes .

We elucidate the molecular mechanism causing their priming , demonstrate that stalled RNA polymerase II and H3K4me3 accumulate as epigenetic marks at the JA-primed ABA-dependent genes before actual transcription , and describe how these events occur mechanistically .

The transcription factor MYC2 binds to the genes in response to both dehydration stress and to JA and determines the specificity of the priming .

The MEDIATOR subunit MED25 links JA-priming with dehydration stress response pathways at the transcriptional level .

Possible biological relevance of primed enhanced transcription from the specific memory genes is discussed .

CONCLUSIONS : The biotic stress hormone JA potentiated transcription from a specific subset of ABA-response genes , revealing a novel aspect of the JA- and ABA-signaling pathways ' interactions .

H3K4me3 functions as an epigenetic mark at JA-primed dehydration stress response genes before transcription .

We emphasize that histone and epigenetic marks are not synonymous and argue that distinguishing between them is important for understanding the role of chromatin marks in genes ' transcriptional performance .

JA-priming , specifically of dehydration stress memory genes encoding cell/membrane protective functions , suggests it is an adaptational response to two different environmental stresses .


The oxidative deamination of N-methylputrescine is an essential step in both pyridine and tropane alkaloid biosynthesis .

Reverse genetic approaches have not resulted in the cloning of a methylputrescine oxidase gene ( MPO ) .

However , we have used a homology-based approach to clone a full-length tobacco MPO1 cDNA .

The MPO1 gene is part of a small multigene family comprised of approximately six members .

MPO1-like transcript levels increased in roots that were either deprived of auxin or treated with methyl jasmonic acid .

Similar to other known nicotine biosynthetic genes in domesticated tobacco , MPO1-like mRNA levels were lower in roots with the mutant a and b alleles .

The MPO1 protein was expressed in bacteria as a recombinant Thioredoxin-His(6)-MPO1 fusion protein .

The recombinant MPO1 protein utilized N-methylputrescine more efficiently than other diamines .

Therefore , the kinetic properties of the MPO1 enzyme may play an important role in determining the pyridine alkaloid profiles observed in tobacco roots .


How plants perceive insect attacks is an area of active research .

Numerous studies have shown that regurgitant from feeding insects elicits a defense response in plants , which is often assumed to be distinct from a wound response .

We have characterized the inducible defense response in hybrid poplar and found it to be qualitatively similar between wounding and application of regurgitant from forest tent caterpillar .

We suggest that this is likely attributable to our wounding treatment which is much more intense compared to most other studies .

These overlapping responses appear to be activated via jasmonic acid signaling , and we speculate that they are both triggered by elicitors of plant origin .

Wounding would release such elicitor molecules when leaf cells are disrupted , and regurgitant may contain them in a modified or processed form .

This hypothesis could explain why some other necrosis-inducing stresses also induce herbivore defense genes .


BACKGROUND : Sugarcane smut caused by Sporisorium scitamineum is one of the most severe fungal diseases in the sugarcane industry .

Using a molecular biological technique to mine sugarcane resistance genes can provide gene resources for further genetic engineering of sugarcane disease-resistant breeding .

Jasmonate ZIM ( zinc-finger inflorescence meristem ) domain ( JAZ ) proteins , which involved in the responses to plant pathogens and abiotic stresses , are important signaling molecules of the jasmonic acid ( JA ) pathway .

RESULTS : Seven differentially expressed sugarcane JAZ genes , ScJAZ1-ScJAZ7 , were mined from the transcriptome of sugarcane after inoculation with S. scitamineum .

Bioinformatic analyses revealed that these seven ScJAZ genes encoded basic proteins that contain the TIFY and CCT_2 domains .

Quantitative reverse transcription polymerase chain reaction ( qRT-PCR ) analysis demonstrated that the ScJAZ1-ScJAZ7 genes were tissue specific and differentially expressed under adverse stress .

During S. scitamineum infection , the transcripts of ScJAZ4 and ScJAZ5 were both upregulated in the susceptible genotype ROC22 and the resistant genotype Yacheng05 - 179 ; ScJAZ1 , ScJAZ2 , ScJAZ3 , and ScJAZ7 were downregulated in Yacheng05 - 179 and upregulated in ROC22 ; and the expression of ScJAZ6 did not change in ROC22 , but was upregulated in Yacheng05 - 179 .

The transcripts of the seven ScJAZ genes were increased by the stimuli of salicylic acid and abscisic acid , particularly methyl jasmonate .

The expression of the genes ScJAZ1-ScJAZ7 was immediately upregulated by the stressors hydrogen peroxide , sodium chloride , and copper chloride , whereas slightly induced after treatment with calcium chloride and polyethylene glycol .

In addition , the expression of ScJAZ6 , as well as seven tobacco immunity-associated marker genes were upregulated , and antimicrobial activity against Pseudomonas solanacearum and Fusarium solani var . coeruleum was observed during the transient overexpression of ScJAZ6 in Nicotiana benthamiana , suggesting that the ScJAZ6 gene is associated with plant immunity .

CONCLUSIONS : The different expression profiles of the ScJAZ1-ScJAZ7 genes during S. scitamineum infection , the positive response of ScJAZ1-ScJAZ7 to hormones and abiotic treatments , and the function analysis of the ScJAZ6 gene revealed their involvement in the defense against biotic and abiotic stresses .

The findings of the present study facilitate further research on the ScJAZ gene family especially their regulatory mechanism in sugarcane .


Global warming frequently leads to extreme temperatures , which pose a serious threat to the growth , development , and yield formation of crops such as maize .

This study aimed to deeply explore the molecular mechanisms of young ear development under heat stress .

We selected the heat-tolerant maize variety Zhengdan 958 ( T ) and heat-sensitive maize variety Xianyu 335 ( S ) , and subjected them to heat stress in the V9 ( 9th leaf ) , V12 ( 12th leaf ) , and VT ( tasseling ) growth stages .

We combined analysis of the maize phenotype with omics technology and physiological indicators to compare the differences in young ear morphology , total number of florets , floret fertilization rate , grain abortion rate , number of grains , and main metabolic pathways between plants subjected to heat stress and those left to develop normally .

The results showed that after heat stress , the length and diameter of young ears , total number of florets , floret fertilization rate , and number of grains all decreased significantly , whereas the length of the undeveloped part at the top of the ear and grain abortion rate increased significantly .

In addition , the differentially expressed genes ( DEGs ) in young ears were significantly enriched in the hormone signaling pathways .

The endogenous hormone content in young ears exhibited different changes : zeatin ( ZT ) and zeatin riboside ( ZR ) decreased significantly , but gibberellin acid(3 ) ( GA(3 ) ) , gibberellin acid(4 ) ( GA(4 ) ) , and abscisic acid ( ABA ) increased significantly , in ears subjected to heat stress .

In the heat-tolerant maize variety , the salicylic acid ( SA ) , and jasmonic acid ( JA ) content in the vegetative growth stage also increased in ears subjected to heat stress , whereas the opposite effect was observed for the heat-sensitive variety .

The changes in endogenous hormone content of young ears that were subjected to heat stress significantly affected ear development , resulting in a reduction in the number of differentiated florets , fertilized florets and grains , which ultimately reduced the maize yield .


Salicylic acid ( SA ) , jasmonic acid ( JA ) , ethylene ( ET ) , and their interactions mediate plant responses to pathogen and herbivore attack .

JA-SA and JA-ET cross-signaling are well studied , but little is known about SA-ET cross-signaling in plant-herbivore interactions .

When the specialist herbivore tobacco hornworm ( Manduca sexta ) attacks Nicotiana attenuata , rapid and transient JA and ET bursts are elicited without significantly altering wound-induced SA levels .

In contrast , attack from the generalist beet armyworm ( Spodoptera exigua ) results in comparatively lower JA and ET bursts , but amplified SA bursts .

These phytohormone responses are mimicked when the species ' larval oral secretions ( OS(Se ) and OS(Ms ) ) are added to puncture wounds .

Fatty acid-amino acid conjugates elicit the JA and ET bursts , but not the SA burst .

OS(Se ) had enhanced glucose oxidase activity ( but not beta-glucosidase activity ) , which was sufficient to elicit the SA burst and attenuate the JA and ET levels .

It is known that SA antagonizes JA ; glucose oxidase activity and associated hydrogen peroxide also antagonizes the ET burst .

We examined the OS(Ms)-elicited SA burst in plants impaired in their ability to elicit JA ( antisense [as]-lox3 ) and ET ( inverted repeat [ir]-aco ) bursts and perceive ET ( 35s-etr1b ) after fatty acid-amino acid conjugate elicitation , which revealed that both ET and JA bursts antagonize the SA burst .

Treating wild-type plants with ethephone and 1-methylcyclopropane confirmed these results and demonstrated the central role of the ET burst in suppressing the OS(Ms)-elicited SA burst .

By suppressing the SA burst , the ET burst likely facilitates unfettered JA-mediated defense activation in response to herbivores that otherwise would elicit SA .


In Nicotiana sylvestris , a set of nicotine biosynthesis genes were activated by exogenous application of methyl jasmonate , but the activation was effectively suppressed by simultaneous treatment with ethylene .

When N. sylvestris transgenic hairy roots were treated with a natural ethylene precursor , the jasmonate-responsive expression of the promoter from a nicotine pathway enzyme gene was completely suppressed , and this suppressive effect was abolished when ethylene perception was blocked with silver cation .

These and additional immunoblot results suggest that ethylene signal antagonizes jasmonate signal in nicotine biosynthesis .


The volatile metabolite methyl jasmonate ( MeJA ) plays an important role in intra- and interplant communication and is involved in diverse biological processes .

In this study , we report the cloning and functional characterization of a S-adenosyl-l-methionine : jasmonic acid carboxyl methyltransferase ( JMT ) from Fragaria vesca and Fragaria × ananassa .

Biochemical assays and comprehensive transcript analyses showed that JMT has been erroneously annotated as gene fusion with a carboxyl methyltransferase ( CMT ) ( gene15184 ) in the first published genome sequence of F. vesca .

Recombinant FvJMT catalyzed the formation of MeJA with KM value of 22.3μM while FvCMT and the fusion protein were almost inactive .

Activity of JMT with benzoic acid and salicylic acid as substrates was less than 1.5 % of that with JA .

Leucine at position 245 , an amino acid missing in other JMT sequences is essential for activity of FvJMT .

In accordance with MeJA levels , JMT transcript levels decreased steadily during strawberry fruit ripening , as did the expression levels of JA biosynthesis and regulatory genes .

It appears that CMT has originated by a recent duplication of JMT and lost its enzymatic activity toward JA .

In the newest version of the strawberry genome sequence ( June 2014 ) CMT and JMT are annotated as separate genes in accordance with differential temporal and spatial expression patterns of both genes in Fragaria sp. In conclusion , MeJA , the inactive derivative of JA , is probably involved in early steps of fruit development by modulating the levels of the active plant hormone JA .


Protease inhibitors ( PIs ) function in the precise regulation of proteases , and are thus involved in diverse biological processes in many organisms .

Here , we studied the functions of the Arabidopsis UNUSUAL SERINE PROTEASE INHIBITOR ( UPI ) gene , which encodes an 8.8 kDa protein of atypical sequence relative to other PIs .

Plants harboring a loss-of-function UPI allele displayed enhanced susceptibility to the necrotrophic fungi Botrytis cinerea and Alternaria brassicicola as well as the generalist herbivore Trichoplusia ni .

Further , ectopic expression conferred increased resistance to B. cinerea and T. ni .

In contrast , the mutant has wild-type responses to virulent , avirulent and non-pathogenic strains of Pseudomonas syringae , thus limiting the defense function of UPI to necrotrophic fungal infection and insect herbivory .

Expression of UPI is significantly induced by jasmonate , salicylic acid and abscisic acid , but is repressed by ethylene , indicating complex phytohormone regulation of UPI expression .

The upi mutant also shows significantly delayed flowering , associated with decreased SOC1 expression and elevated levels of MAF1 , two regulators of floral transition .

Recombinant UPI strongly inhibits the serine protease chymotrypsin but also weakly blocks the cysteine protease papain .

Interestingly , jasmonate induces intra- and extracellular UPI accumulation , suggesting a possible role in intercellular or extracellular functions .

Overall , our results show that UPI is a dual-specificity PI that functions in plant growth and defense , probably through the regulation of endogenous proteases and/or those of biotic invaders .


Plants subjected to drought and saline stress conditions suffer from tissue dehydration .

Such dehydration is caused by the imbalance between root water uptake by roots and water loss by transpiration .

Therefore , determination of root hydraulic properties is crucial to understand plant water balance .

Root hydraulic conductivity ( L ) can be used to estimate root water transport capacity .

L depends on root architecture ( length and diameter of the root and proliferation of secondary roots ) , radial water transport pathway ( root xylem vessels , plasmodesmata , apoplastic space , caspary bands ) , and on intrinsic membrane permeability to water ( aquaporins , water membrane protein channels ) .

Different methods have been developed to measure L , such as Pressure Chamber , Free Exudation , High-Pressure Flowmeter ( HPFM ) , and Root Pressure Probe ( RPP ) .

In this chapter , we will focus on Pressure Chamber , Free Exudation , and HPFM methods which have been used to determine the effect of jasmonates ( JA ) on root hydraulic conductivity .


BACKGROUND : Breeding for genes controlling key agronomic traits is an important goal of rice genetic improvement .

To gain insight into genes controlling grain morphology , we screened M(3 ) plants derived from 1,000 whole-genome sequenced ( WGS ) M(2 ) Kitaake mutants to identify lines with altered grain size .

RESULTS : In this study , we isolated a mutant , named fast-neutron ( FN ) 60 - 4 , which exhibits a significant reduction in grain size .

We crossed FN60 - 4 with the parental line Kitaake and analyzed the resulting backcross population .

Segregation analysis of 113 lines from the BC(2)F(2 ) population revealed that the mutant phenotype is controlled by a single semi-dominant locus .

Mutant FN60 - 4 is reduced 20 % in plant height and 8.8 % in 1000-grain weight compared with Kitaake .

FN60 - 4 also exhibits an 8 % reduction in cell number and a 9 % reduction in cell length along the vertical axis of the glume .

We carried out whole-genome sequencing of DNA pools extracted from segregants with long grains or short grains , and revealed that one gene , LOC_Os09g02650 , cosegregated with the grain size phenotype in the BC(1)F(2 ) and BC(2)F(2 ) populations .

This mutant allele was named grain shape 9 - 1 ( gs9 - 1 ) .

gs9 - 1 carries a 3-bp deletion that affects two amino acids .

This locus is a new allele of the BC12/GDD1/MTD1 gene that encodes a kinesin-like protein involved in cell-cycle progression , cellulose microfibril deposition and gibberellic acid ( GA ) biosynthesis .

The GA biosynthesis-related gene KO2 is down-regulated in gs9 - 1 .

The dwarf phenotype of gs9 - 1 can be rescued by adding exogenous GA(3 ) .

In contrast to the phenotypes for the other alleles , the gs9 - 1 is less severe , consistent with the nature of the mutation , which does not disrupt the open reading frame as observed for the other alleles .

CONCLUSIONS : In this study , we isolated a mutant , which exhibits altered grain shape and identified the mutated gene , gs9 - 1 .

Our study reveals that gs9 - 1 is a semi-dominant gene that carries a two-amino acid mutation .

gs9 - 1 is allelic to the BC12/GDD1/MTD1 gene involved in GA biosynthesis .

These results demonstrate the efficiency and convenience of cloning genes from the whole-genome sequenced Kitaake mutant population to advance investigations into genes controlling key agronomic traits in rice .


Germination is a process of seed sprouting that facilitates embryo growth .

The breakdown of reserved starch in the endosperm into simple sugars is essential for seed germination and subsequent seedling growth .

At the early stage of germination , gibberellic acid ( GA ) activates transcription factor GAMYB to promote de novo synthesis of isoforms of α-amylase in the aleurone layer and scutellar epithelium of the embryo .

Here , we demonstrate that wheat germination is regulated by plant target of rapamycin ( TOR ) signaling .

TOR is a central component of the essential-nutrient-dependent pathway controlling cell growth in all eukaryotes .

It is known that rapamycin , a highly specific allosteric inhibitor of TOR , is effective in yeast and animal cells but ineffective in most of higher plants likely owing to structural differences in ubiquitous rapamycin receptor FKBP12 .

The action of rapamycin on wheat growth has not been studied .

Our data show that rapamycin inhibits germination of wheat seeds and of their isolated embryos in a dose-dependent manner .

The involvement of Triticum aestivum TOR ( TaTOR ) in wheat germination was consistent with the suppression of wheat embryo growth by specific inhibitors of the TOR kinase : pp242 or torin1 .

Rapamycin or torin1 interfered with GA function in germination because of a potent inhibitory effect on α-amylase and GAMYB gene expression .

The TOR inhibitors selectively targeted the GA-dependent gene expression , whereas expression of the abscisic acid-dependent ABI5 gene was not affected by either rapamycin or torin1 .

To determine whether the TaTOR kinase activation takes place during wheat germination , we examined phosphorylation of a ribosomal protein , T. aestivum S6 kinase 1 ( TaS6K1 ; a substrate of TOR ) .

The phosphorylation of serine 467 ( S467 ) in a hydrophobic motif on TaS6K1 was induced in a process of germination triggered by GA .

Moreover , the germination-induced phosphorylation of TaS6K1 on S467 was dependent on TaTOR and was inhibited by rapamycin or torin1 .

Besides , a gibberellin biosynthesis inhibitor ( paclobutrazol ; PBZ ) blocked not only α-amylase gene expression but also TaS6K1 phosphorylation in wheat embryos .

Thus , a hormonal action of GA turns on the synthesis of α-amylase in wheat germination via activation of the TaTOR-S6K1 signaling pathway .


Effects of ethylene , gibberellins , and kinetin on the germination of two lots of Chenopodium album L. seeds , collected from the field in 1982 and 1983 , were studied in relation to the availability of nitrate .

The experiments were conducted in darkness and at temperatures ranging from 12 to 32 degrees C. Ethylene induced over 75 % germination in the 1983 seed but had little effect on the 1982 seed .

Nitrate was only slightly promotive in either of the two seed lots .

A combination of ethylene and nitrate , however , acted synergistically on 1982 seed , resulting in as much germination as that induced in 1983 seed by ethylene alone .

In 1983 seed , a combination of ethylene and nitrate was only marginally more effective than ethylene .

A similar relationship was observed in the effects of gibberellic acid(4 + 7 ) ( GA(4 + 7 ) ) and nitrate on seeds from the two lots .

The 1982 seed , which responded synergistically to combinations of nitrate with ethylene or GA(4 + 7 ) was found to contain an extremely low endogenous level of nitrate as compared to 1983 seed .

Thus , high levels of either endogenous or applied nitrate appeared to enhance the germination response to ethylene or GA(4 + 7).Kinetin had no effect on 1982 seed and only a small promotive effect on 1983 seed .

There was no synergism between kinetin and nitrate in either of the seed lots .


Herbivore attacks induce leaves to emit a specific blend of volatiles .

Here we show that exposure to Tetranychus urticae-induced volatiles , as well as T. urticae infestation and artificial wounding , activates the transcription of the genes involved in the biosynthesis of ethylene [ S-adenosylmethionine ( SAM ) synthetase and 1-aminocyclopropane-1-carboxylic acid oxidase ] and a gene involved in the biosynthesis of polyamines from SAM ( SAM decarboxylase ) in lima bean leaves .

Moreover , exposure of leaves to any one of the seven major chemical components of T. urticae-induced volatiles also induces expression of these genes .

Furthermore , we found that , when lima bean plants were exposed to T. urticae-induced volatiles , they emitted ethylene .

Lima bean plants infested by T. urticae and artificially wounded plants also emitted ethylene .

Endogenous polyamine levels were not increased in the exposed leaves or the infested leaves , suggesting that polyamine production from SAM was only slightly promoted at the metabolic levels present in the leaves .

We found that jasmonate ( JA ) accumulated in leaves exposed to T. urticae-induced volatiles , and that both JA and salicylate ( SA ) accumulated in leaves infested by T. urticae .

These findings , as well as results of pharmacological analyses , suggest that , in leaves exposed to T. urticae-induced volatiles , ethylene biosynthesis might be regulated by pathways involving JA and the ethylene positive feedback loop .

They also suggest that ethylene biosynthesis might be regulated by signaling pathways involving JA , SA and ethylene in T. urticae-infested leaves .


A highly sensitive and accurate multiplex gas chromatography-mass spectrometry (GC-MS/MS)-technique is reported for the quantitative analysis of acidic phytohormones in Arabidopsis thaliana and other plant species .

The optimized setup allows the routine processing and analysis of between 20 mg and 5 g of tissue .

The protocol was designed and the equipment used was chosen to facilitate implementation of the method into other laboratories and to provide access to state-of-the-art analytical tools for the acidic phytohormones and related signaling molecules .


A wheat ethylene receptor homologue ( W-er1 ) was isolated from a wheat stem cDNA library using the Arabidopsis ETR1 cDNA as a probe .

The predicted amino acid sequence of W-er1 is over 70 % similar to ERS1 from Arabidopsis and exhibits homology to bacterial two-component response regulators within the histidine kinase domain .

Northern hybridization demonstrated that W-er1 was expressed in stem , leaf and root tissues .

Treatments known to induce senescence of detached leaves including jasmonate , abscisic acid and wounding , increased the accumulation of W-er1 mRNA , while benzyladenine treatment did not .

These data suggest that W-er1 may play a role in the process of leaf senescence .


The patatin-related phospholipase A ( pPLA ) hydrolyzes membrane glycerolipids to produce monoacyl compounds and free fatty acids .

Phospholipids are cleaved by pPLAIIα at the sn-1 and sn-2 positions , and galactolipids , including those containing oxophytodienoic acids , can also serve as substrates .

Ablation of pPLAIIα decreased lysophosphatidylcholine and lysophosphatidylethanolamine levels , but increased free linolenic acid .

pPLAIIα-deficient plants displayed a higher level of jasmonic acid and methyl jasmonate , as well as the oxylipin-biosynthetic intermediates 13-hydroperoxylinolenic acid and 12-oxophytodienoic acid than wild-type ( WT ) plants .

The expression of genes involved in oxylipin production was also higher in the pPLAIIα-deficient mutant than in WT plants .

The mutant plants lost water more quickly than WT plants .

The stomata of WT and mutant plants responded similarly to abscisic acid .

In response to desiccation , the mutant and WT leaves produced abscisic acid at the same rate , but , after 4 h of desiccation , the jasmonic acid level was much higher in mutant than WT leaves .

These results indicate that pPLAIIα negatively regulates oxylipin production and suggest a role in the removal of oxidatively modified fatty acids from membranes .


GP-1 , a novel glycoprotein from Streptomyces sp. ZX01 has a plant immunity-inducing effect .

GP-1-treated plants exhibited enhanced systemic resistance with a significant reduction in TMV lesions on tobacco leaves , but its antiviral mechanism remains unclear .

In this study , early plant defense-related responses , such as Ca(2 + ) influx , callose apposition , oxidative burst , hypersensitive response , programmed cell death , increase in nitric oxide ( NO ) , and stomatal closure , were investigated under GP-1 treatment , and the mechanism of how GP-1 induces viral resistance in Nicotiana benthamiana was studied .

Results showed that GP-1 induced [Ca(2+)](cyt ) rapidly in tobacco leaves and suspended cells , followed by reactive oxygen species ( ROS ) and NO elevation .

Transcriptome analysis showed significant differences in expression levels between the GP-1-treated N. benthamiana and the control and showed significantly upregulated and enriched pathways including defense and immune reaction .

Similar to typical pathogen-associated molecular patterns , GP-1 induced callose deposition and stomatal closure to form defense barriers against pathogen invasion .

The expression of defense-related genes further confirmed the above conclusions .

By analyzing transcriptome in N. benthamiana and the contents of salicylic acid ( SA ) and jasmonic acid ( JA ) , GP-1 enhanced viral resistance of tobacco by improving the SA and JA contents , strengthening plant secondary metabolites activities , promoting systemic accumulation of pathogenesis-related proteins in TMV- inoculated tobacco there by producing antiviral activity .


Infection by necrotrophs is a complex process that starts with the breakdown of the cell wall ( CW ) matrix initiated by CW-degrading enzymes and results in an extensive tissue maceration .

Plants exploit induced defense mechanisms based on biochemical modification of the CW components to protect themselves from enzymatic degradation .

The pectin matrix is the main CW target of Botrytis cinerea , and pectin methylesterification status is strongly altered in response to infection .

The methylesterification of pectin is controlled mainly by pectin methylesterases ( PMEs ) , whose activity is posttranscriptionally regulated by endogenous protein inhibitors ( PMEIs ) .

Here , AtPMEI10 , AtPMEI11 , and AtPMEI12 are identified as functional PMEIs induced in Arabidopsis ( Arabidopsis thaliana ) during B. cinerea infection .

AtPMEI expression is strictly regulated by jasmonic acid and ethylene signaling , while only AtPMEI11 expression is controlled by PME-related damage-associated molecular patterns , such as oligogalacturonides and methanol .

The decrease of pectin methylesterification during infection is higher and the immunity to B. cinerea is compromised in pmei10 , pmei11 , and pmei12 mutants with respect to the control plants .

A higher stimulation of the fungal oxalic acid biosynthetic pathway also can contribute to the higher susceptibility of pmei mutants .

The lack of PMEI expression does not affect hemicellulose strengthening , callose deposition , and the synthesis of structural defense proteins , proposed as CW-remodeling mechanisms exploited by Arabidopsis to resist CW degradation upon B. cinerea infection .

We show that PME activity and pectin methylesterification are dynamically modulated by PMEIs during B. cinerea infection .

Our findings point to AtPMEI10 , AtPMEI11 , and AtPMEI12 as mediators of CW integrity maintenance in plant immunity .


Lettuce ( Lactuca sativa L. ) endosperm cell walls isolated prior to radicle emergence underwent autohydrolysis , the rate of which was correlated with whether radicle emergence would subsequently occur .

Extraction of endosperm cell walls with 6 M LiCl suppressed autohydrolysis , and the desalted extract possessed activity that was capable of hydrolyzing purified locust bean galactomannan but not arabinogalactan , carboxymethylcellulose , glucomannan , polygalacturonic acid , tomato galactomannan , or native lettuce endosperm cell walls .

Some hydrolytic activity was detected on endosperm cell walls if they were modified by partial trifluoroacetic acid hydrolysis or pretreatment with guanidinium thiocyanate .

In extended incubations the cell wall enzyme extract released only large molecular mass fragments from locust bean galactomannan , indicating primarily endo-activity .

Galactomannan-hydrolyzing activity in the cell wall extract increased as a function of imbibition time and was greatest just prior to radicle emergence .

Thermoinhibition ( imbibition at 32[deg]C ) or treatment with abscisic acid at a temperature optimal for germination ( 25[deg]C ) suppressed both germination and endosperm cell wall mannanase activity , whereas alleviation of thermoinhibition with gibberellic acid was accompanied by significant enhancement of mannanase activity .

We conclude that a cell wall-bound endo-[beta]-mannanase is expressed in lettuce endosperm prior to radicle emergence and is regulated by the same conditions that govern germination .


Leaf angle is an important agronomic trait in cereals and shares a close relationship with crop architecture and grain yield .

Although it has been previously reported that ZmCLA4 can influence leaf angle , the underlying mechanism remains unclear .

In this study , we used the Gal4-LexA/UAS system and transactivation analysis to demonstrate in maize ( Zea mays ) that ZmCLA4 is a transcriptional repressor that regulates leaf angle .

DNA affinity purification sequencing ( DAP-Seq ) analysis revealed that ZmCLA4 mainly binds to promoters containing the EAR motif ( CACCGGAC ) as well as to two other motifs ( CCGARGS and CDTCNTC ) to inhibit the expression of its target genes .

Further analysis of ZmCLA4 target genes indicated that ZmCLA4 functions as a hub of multiple plant hormone signaling pathways : ZmCLA4 was found to directly bind to the promoters of multiple genes including ZmARF22 and ZmIAA26 in the auxin transport pathway , ZmBZR3 in the brassinosteroid signaling pathway , two ZmWRKY genes involved in abscisic acid metabolism , ZmCYP genes ( ZmCYP75B1 , ZmCYP93D1 ) related to jasmonic acid metabolism , and ZmABI3 involved in the ethylene response pathway .

Overall , our work provides deep insights into the ZmCLA4 regulatory network in controlling leaf angle in maize .


In order to characterize a specific extracellular 21-kDa calmodulin-binding protein ( named : ECBP21 ) from Angelica dahurica L. suspension-cultured cells , the cDNA coding for the protein has been cloned .

Here , Southern blot analysis shows that there are at least two copies of ECBP21 gene in Angelica genome .

Using truncated versions of ECBP21 and synthetic peptide in CaM binding assays , we mapped the calmodulin-binding domain to a 16-amino acid stretch ( residues 200 - 215 ) at the C-terminal region .

The ECBP21 was localized in the cell wall area by the immunogold electron microscopy and by GFP labeling method .

These results define ECBP21 as a kind of an extracellular calmodulin-binding protein ( CaMBP ) .

Furthermore , using Northern blot analysis , we examined the expression dynamics of ecbp21 during the incubation of Angelica suspension-cultured cells and the treatments with some growth regulators .

The above studies further provide the molecular evidence for the existence of the gene coding for extracellular CaMBPs and imply a possible role for ECBP21 .


Abscisic acid ( ABA ) inhibits the production of ethylene induced by water stress in excised wheat leaves and counteracts the stimulatory effect of 6-benzyladenine ( BA ) on this process .

The stimulatory effect of BA and the inhibitory effect of ABA were equally pronounced whether external or endogenous ethylene levels were determined .

When leaves were sprayed or floated on solutions of BA , indole-3-acetic acid ( IAA ) , gibberellic acid ( GA3 ) , or ABA , the relative activities of these growth regulators on stress-induced ethylene at 10(-4 ) mol l(-1 ) were BA > IAA > GA3>controls > ABA .

In non-stressed leaves , however , where the levels of ethylene produced were 2 - 20 times smaller , the relative activities were IAA > BA > GA3>controls > ABA .

The effects of BA and ABA spray treatment on water stress induced ethylene were closely similar whether the solutions were applied 2 or 18 h prior to the initiation of water stress .

The relationships between the levels of endogenous growth regulators in the plant and ethylene release induced by water stress are discussed .


Reducing phenylpropanoid biosynthesis in transgenic tobacco compromises systemic acquired resistance ( SAR ) to tobacco mosaic virus , while increasing phenylpropanoid biosynthesis enhances SAR .

Surprisingly , transgenic tobacco plants compromised in SAR exhibit more effective grazing-induced systemic resistance to larvae of Heliothis virescens , whereas induced insect resistance is compromised in transgenic plants with elevated phenylpropanoid levels .

Levels of the phenylpropanoid-derived signal salicylic acid are directly correlated with overall phenylpropanoid biosynthesis in this series of transgenic plants .

Moreover , while pathogen-induced SAR is almost completely compromised in salicylic acid-deficient plants expressing the bacterial nahG salicylate hydroxylase gene , these plants show enhanced grazing-induced insect resistance compared to wild-type .

Hence , suppression of grazing-induced insect resistance is mediated at least in part by salicylic acid and likely reflects salicylic acid inhibition of the synthesis and action of the wound signal jasmonic acid .

We propose that the dual functions of salicylic acid contribute to a signal poise which constrains constitutive expression of disease and insect resistance mechanisms , and reciprocally switches their selective activation .


Plants sense and respond to microbes utilizing a multilayered signalling cascade .

In seed plants , the phytohormones jasmonic and salicylic acid ( JA and SA ) are key denominators of how plants respond to certain microbes .

Their interplay is especially well-known for tipping the scales in plants ' strategies of dealing with phytopathogens .

In non-angiosperm lineages , the interplay is less well understood , but current data indicate that it is intertwined to a lesser extent and the canonical JA/SA antagonism appears to be absent .

Here , we used the water fern Azolla filiculoides to gain insights into the fern 's JA/SA signalling and the molecular communication with its unique nitrogen fixing cyanobiont Nostoc azollae , which the fern inherits both during sexual and vegetative reproduction .

By mining large-scale sequencing data , we demonstrate that Azolla has most of the genetic repertoire to produce and sense JA and SA .

Using qRT-PCR on the identified biosynthesis and signalling marker genes , we show that Azolla is responsive to exogenously applied SA .

Furthermore , exogenous SA application influenced the abundance and gene expression of Azolla 's cyanobiont .

Our data provide a framework for JA/SA signalling in ferns and suggest that SA might be involved in Azolla 's communication with its vertically inherited cyanobiont .


Plants counteract attack by herbivorous insects using a variety of inducible defence mechanisms .

The production of toxic proteins and metabolites that instantly affect the herbivore 's development are examples of direct induced defence .

In addition , plants may release mixtures of volatile organic compounds ( VOCs ) that indirectly protect the plant by attracting natural enemies of the herbivore .

Recent studies suggest that these VOCs can also prime nearby plants for enhanced induction of defence upon future insect attack .

However , evidence that this defence priming causes reduced vulnerability to insects is sparse .

Here we present molecular , chemical and behavioural evidence that VOC-induced priming leads to improved direct and indirect resistance in maize .

A differential hybridization screen for inducible genes upon attack by Spodoptera littoralis caterpillars identified 10 defence-related genes that are responsive to wounding , jasmonic acid ( JA ) , or caterpillar regurgitant .

Exposure to VOCs from caterpillar-infested plants did not activate these genes directly , but primed a subset of them for earlier and/or stronger induction upon subsequent defence elicitation .

This priming for defence-related gene expression correlated with reduced caterpillar feeding and development .

Furthermore , exposure to caterpillar-induced VOCs primed for enhanced emissions of aromatic and terpenoid compounds .

At the peak of this VOC emission , primed plants were significantly more attractive to parasitic Cotesia marginiventris waSPS .

This study shows that VOC-induced priming targets a specific subset of JA-inducible genes , and links these responses at the molecular level to enhanced levels of direct and indirect resistance against insect attack .


Inducible anti-herbivore defenses in plants are predominantly regulated by jasmonic acid ( JA ) .

On tomato plants , most genotypes of the herbivorous generalist spider mite Tetranychus urticae induce JA defenses and perform poorly on it , whereas the Solanaceae specialist Tetranychus evansi , who suppresses JA defenses , performs well on it .

We asked to which extent these spider mites and the predatory mite Phytoseiulus longipes preying on these spider mites eggs are affected by induced JA-defenses .

By artificially inducing the JA-response of the tomato JA-biosynthesis mutant def-1 using exogenous JA and isoleucine ( Ile ) , we first established the relationship between endogenous JA-Ile-levels and the reproductive performance of spider mites .

For both mite species we observed that they produced more eggs when levels of JA-Ile were low .

Subsequently , we allowed predatory mites to prey on spider mite-eggs derived from wild-type tomato plants , def-1 and JA-Ile-treated def-1 and observed that they preferred , and consumed more , eggs produced on tomato plants with weak JA defenses .

However , predatory mite oviposition was similar across treatments .

Our results show that induced JA-responses negatively affect spider mite performance , but positively affect the survival of their offspring by constraining egg-predation .


Jasmonic acid and its derived metabolites ( JAs ) orchestrate plant defense against insects and fungi . 12-Oxo-phytodienoic acid ( OPDA ) , a JA precursor , has also been implicated in plant defense .

We sought to define JAs and OPDA functions through comparative defense susceptibility characteristics of three Arabidopsis ( Arabidopsis thaliana ) genotypes : aos , lacking JAs and OPDA ; opda reductase3 ( opr3 ) , deficient in JA production but can accumulate OPDA ; and transgenics that overexpress OPR3 .

opr3 , like aos , is susceptible to cabbage loopers ( Trichoplusia ni ) but , relative to aos , opr3 has enhanced resistance to a necrotrophic fungus .

Gas chromatography-mass spectrometry reveals that opr3 produces OPDA but no detectable JAs following wounding and looper infestation ; unexpectedly , substantial levels of JAs accumulate in opr3 upon fungal infection .

Full-length OPR3 transcripts accumulate in fungal-infected opr3 , potentially through splicing of the T-DNA containing intron .

Fungal resistance correlates with levels of JAs not OPDA ; therefore , opr3 resistance to some pests is likely due to JA accumulation , and signaling activities ascribed to OPDA should be reassessed because opr3 can produce JAs .

Together these data ( 1 ) reinforce the primary role JAs play in plant defense against insects and necrotrophic fungi , ( 2 ) argue for a reassessment of signaling activities ascribed to OPDA , and ( 3 ) provide evidence that mutants with intron insertions can retain gene function .