slotreck/pickle huggingface dataset:
Recently , six genes of the gibberellin ( GA ) biosynthesis gene cluster in Gibberella fujikuroi were cloned and the functions of five of these genes were determined . Here we describe the function of the sixth gene , P450 - 3 , and the cloning and functional analysis of a seventh gene , orf3 , located at the left border of the gene cluster . We have thereby defined the complete GA biosynthesis gene cluster in this fungus . The predicted amino acid sequence of orf3 revealed no close homology to known proteins . High performance liquid chromatography and gas chromatography-mass spectrometry analyses of the culture fluid of knock-out mutants identified GA1 and GA4 , rather than GA3 and GA7 , as the major C19-GA products , suggesting that orf3 encodes the GA4 1,2-desaturase . This was confirmed by transformation of the SG139 mutant , which lacks the GA biosynthesis gene cluster , with the desaturase gene renamed des . The transformants converted GA4 to GA7 , and also metabolized GA9 ( 3-deoxyGA4 ) to GA120 ( 1,2-didehydroGA9 ) , but the 2alpha-hydroxylated compound GA40 was the major product in this case . We demonstrate also by gene disruption that P450 - 3 , one of the four cytochrome P450 monooxygenase genes in the GA gene cluster , encodes the 13-hydroxylase , which catalyzes the conversion of GA7 to GA3 , in the last step of the pathway . This enzyme also catalyzes the 13-hydroxylation of GA4 to GA1 . Disruption of the des gene in an UV-induced P450 - 3 mutant produced a double mutant lacking both desaturase and 13-hydroxylase activities that accumulated high amounts of the commercially important GA4 . The des and P450 - 3 genes differ in their regulation by nitrogen metabolite repression . In common with the other five GA biosynthesis genes , expression of the desaturase gene is repressed by high amounts of nitrogen in the culture medium , whereas P450 - 3 is the only gene in the cluster not repressed by nitrogen .
BACKGROUND : Postharvest fruit conservation relies on low temperatures and manipulations of hormone metabolism to maintain sensory properties . Peaches are susceptible to chilling injuries , such as ' woolliness ' that is caused by juice loss leading to a ' wooly ' fruit texture . Application of gibberellic acid at the initial stages of pit hardening impairs woolliness incidence , however the mechanisms controlling the response remain unknown . We have employed genome wide transcriptional profiling to investigate the effects of gibberellic acid application and cold storage on harvested peaches . RESULTS : Approximately half of the investigated genes exhibited significant differential expression in response to the treatments . Cellular and developmental process gene ontologies were overrepresented among the differentially regulated genes , whereas sequences in cell death and immune response categories were underrepresented . Gene set enrichment demonstrated a predominant role of cold storage in repressing the transcription of genes associated to cell wall metabolism . In contrast , genes involved in hormone responses exhibited a more complex transcriptional response , indicating an extensive network of crosstalk between hormone signaling and low temperatures . Time course transcriptional analyses demonstrate the large contribution of gene expression regulation on the biochemical changes leading to woolliness in peach . CONCLUSION : Overall , our results provide insights on the mechanisms controlling the complex phenotypes associated to postharvest textural changes in peach and suggest that hormone mediated reprogramming previous to pit hardening affects the onset of chilling injuries .
We have examined the effect of gibberellic acid ( GA(3 ) ) on the distribution of the enzyme responsible for mobilizing storage triacylglycerol in aleurone cells of Hordeum vulgare L. cv Himalaya . Using cellular fractionation techniques , we find that , in cells that have not been exposed to hormone , neutral lipase activity is principally associated with a pellet containing the membranes of protein bodies . If the cells are exposed to GA(3 ) for at least 1 hour , the majority of the lipase activity becomes associated with the lipid body fraction . The nature of the in vivo association between lipid bodies and protein bodies was examined using ultrarapid freezing followed by freeze-fracture electron microscopy . Our analysis indicates that the phospholipid monolayer surrounding the lipid body is directly continuous with the outer leaflet of the bilayer surrounding the protein body . Based on our data , we propose that lipase can be transferred from protein bodies ( storage form ) to lipid bodies ( active form ) by lateral diffusion within the plane of the fused phospholipid monolayer , and that the transfer can be controlled by gibberellic acid by an unknown mechanism .
In Arabidopsis , the flagellin-derived peptide flg22 elevates antibacterial resistance [ 1 ] and inhibits growth [ 2 ] upon perception via the leucine-rich repeat receptor-like kinase Flagellin-Sensitive 2 ( FLS2 ) [ 3 ] . DELLA proteins are plant growth repressors whose degradation is promoted by the phytohormone gibberellin [ 4 ] . Here , we show that DELLA stabilization contributes to flg22-induced growth inhibition . In addition , we show that DELLAs promote susceptibility to virulent biotrophs and resistance to necrotrophs , partly by altering the relative strength of salicylic acid and jasmonic acid ( JA ) signaling . A quadruple-DELLA mutant ( which lacks four out of the five Arabidopsis DELLA proteins [ 5 ] ) was partially insensitive to gene induction by Methyl-Jasmonate ( MeJA ) , whereas the constitutively active dominant DELLA mutant gai[6 ] was sensitized for JA-responsive gene induction , implicating DELLAs in JA-signaling and/or perception . Accordingly , the elevated resistance of gai to the necrotrophic fungus Alternaria brassicicola and susceptibility to the hemibiotroph Pseudomonas syringae pv . tomato strain DC3000 ( Pto DC3000 ) was attenuated in the JA-insensitive coi1 - 16 mutant [ 7 ] . These findings suggest an explanation for why the necrotrophic fungus Gibberella fujikuroi , causal agent of the foolish-seedling disease of rice , makes gibberellin .
Callus cells of Daucus carota L. have different phenylpropanoid pathways depending on the medium composition . Cells propagated on a medium with gibberellic acid do not accumulate cyanidin but incorporate [(14)C]phenylalanine into chlorogenic acid at a high rate . Cells grown on a medium free of gibberellic acid accumulate cyanidin in very large amounts . We here describe partial purification of hydroxycinnamate : CoA ligase , and its properties in these two cell lines . The enzymes extracted from the two cell populations had different substrate specifities : for that from anthocyanin-containing cells , p-coumaric acid was the best substrate , and caffeic acid and ferulic acid were also activated . With enzyme from anthocyanin-free cells , the lowest Km values were obtained for caffeic acid , while ferulic acid had higher values , and p-coumaric acid was nearly inactive . The enzyme did not separate into isoenzymes during purification . Only on polyacrylamide gels the partially purified enzyme from anthocyanin-containing cells separated into three peaks , and that from anthocyanin-free cells , into only two peaks . This difference is discussed in the context of the lack of activity with p-coumaric acid in anthocyanin-free cells .
Increasing sucrose from 20 to 50 g l(-1 ) in Uncaria tomentosa cell suspension cultures enhanced ursolic acid and oleanolic acid production from 129 + /- 61 to 553 + /- 193 microg g(-1 ) cell dry wt . The maximal concentration of both triterpenes ( 1680 + /- 39 microg g(-1 ) cell dry wt ) was 8 days after elicitation by jasmonic acid , while yeast extract or citrus pectin treatments produced 1189 + /- 20 or 1120 + /- 26 microg g(-1 ) cell dry wt , respectively . The ratio of ursolic acid : oleanolic acid was constant at 70:30 .
Gibberellic acid was found to have no significant effect on amylase activity in attached or detached cotyledons of peas .
Sulfur-containing compounds play an important role in plant stress defense ; however , only a little is known about the molecular mechanisms of regulation of sulfate assimilation by stress . Using known Arabidopsis ( Arabidopsis thaliana ) mutants in signaling pathways , we analyzed regulation of the key enzyme of sulfate assimilation , adenosine 5'-phosphosulfate reductase ( APR ) , by salt stress . APR activity and mRNA levels of all three APR isoforms increased 3-fold in roots after 5 h of treatment with 150 mm NaCl . The regulation of APR was not affected in mutants deficient in abscisic acid ( ABA ) synthesis and treatment of the plants with ABA did not affect the mRNA levels of APR isoforms , showing that APR is regulated by salt stress in an ABA-independent manner . In mutants deficient in jasmonate , salicylate , or ethylene signaling , APR mRNA levels were increased upon salt exposure similar to wild-type plants . Surprisingly , however , APR enzyme activity was not affected by salt in these plants . The same result was obtained in mutants affected in cytokinin and auxin signaling . Signaling via gibberellic acid , on the other hand , turned out to be essential for the increase in APR mRNA by salt treatment . These results demonstrate an extensive posttranscriptional regulation of plant APR and reveal that the sulfate assimilation pathway is controlled by a complex network of multiple signals on different regulatory levels .
Signaling networks among multiple phytohormones fine-tune plant defense responses to insect herbivore attack . Previously , it was reported that the synergistic combination of ethylene ( ET ) and jasmonic acid ( JA ) was required for accumulation of the maize insect resistance1 ( mir1 ) gene product , a cysteine ( Cys ) proteinase that is a key defensive protein against chewing insect pests in maize ( Zea mays ) . However , this study suggests that mir1-mediated resistance to corn leaf aphid ( CLA ; Rhopalosiphum maidis ) , a phloem sap-sucking insect pest , is independent of JA but regulated by the ET-signaling pathway . Feeding by CLA triggers the rapid accumulation of mir1 transcripts in the resistant maize genotype , Mp708 . Furthermore , Mp708 provided elevated levels of antibiosis ( limits aphid population)- and antixenosis ( deters aphid settling)-mediated resistance to CLA compared with B73 and Tx601 maize susceptible inbred lines . Synthetic diet aphid feeding trial bioassays with recombinant Mir1-Cys Protease demonstrates that Mir1-Cys Protease provides direct toxicity to CLA . Furthermore , foliar feeding by CLA rapidly sends defensive signal(s ) to the roots that trigger belowground accumulation of the mir1 , signifying a potential role of long-distance signaling in maize defense against the phloem-feeding insects . Collectively , our data indicate that ET-regulated mir1 transcript accumulation , uncoupled from JA , contributed to heightened resistance to CLA in maize . In addition , our results underscore the significance of ET acting as a central node in regulating mir1 expression to different feeding guilds of insect herbivores .
Cross talk between salicylic acid ( SA ) and jasmonic acid ( JA ) signaling pathways plays an important role in the regulation and fine tuning of induced defenses that are activated upon pathogen or insect attack . Pharmacological experiments revealed that transcription of JA-responsive marker genes , such as PDF1.2 and VSP2 , is highly sensitive to suppression by SA . This antagonistic effect of SA on JA signaling was also observed when the JA pathway was biologically activated by necrotrophic pathogens or insect herbivores , and when the SA pathway was triggered by a biotrophic pathogen . Furthermore , all 18 Arabidopsis ( Arabidopsis thaliana ) accessions tested displayed SA-mediated suppression of JA-responsive gene expression , highlighting the potential significance of this phenomenon in induced plant defenses in nature . During plant-attacker interactions , the kinetics of SA and JA signaling are highly dynamic . Mimicking this dynamic response by applying SA and methyl jasmonate ( MeJA ) at different concentrations and time intervals revealed that PDF1.2 transcription is readily suppressed when the SA response was activated at or after the onset of the JA response , and that this SA-JA antagonism is long lasting . However , when SA was applied more than 30 h prior to the onset of the JA response , the suppressive effect of SA was completely absent . The window of opportunity of SA to suppress MeJA-induced PDF1.2 transcription coincided with a transient increase in glutathione levels . The glutathione biosynthesis inhibitor l-buthionine-sulfoximine strongly reduced PDF1.2 suppression by SA , suggesting that SA-mediated redox modulation plays an important role in the SA-mediated attenuation of the JA signaling pathway .
Genome wide association studies enabled prediction of many candidate genes for flowering , maturity and plant height under differing day-length conditions . Some genes were envisaged only from derived B. rapa . Flowering and plant height are the key life history traits . These are crucial for adaptation and productivity . Current investigations aimed to examine genotypic differences governing days to flowering , maturity and plant height under contrasting day-length conditions ; and identify genomic regions governing the observed phenotypic variations . An association panel comprising 195 inbred lines , representing natural ( NR ) and derived ( DR ) forms of Brassica rapa ( AA ; 2n   =   20 ) , was evaluated at two sowing dates and two locations , representing different day-length regimes . Derived B. rapa is a unique pre-breeding material extracted from B. juncea ( AABB ; 2n   =   36 ) . Population structure analysis , using DArT genotypes established derived B. rapa as a genetic resource distinct from natural B. rapa . Genome wide association studies facilitated detection of many trait associated SNPs . Chromosomes A03 , A05 and A09 harboured majority of these . Functional annotation of the associated SNPs and surrounding genome space(s ) helped to predict 43 candidate genes . Many of these were predicted under specific day-length conditions . Important among these were the genes encoding floral meristem identity ( SPL3 , SPL15 , AP3 , BAM2 ) , photoperiodic responses ( COL2 , AGL18 , SPT , NF-YC4 ) , gibberellic acid biosynthesis ( GA1 ) and regulation of flowering ( EBS ) . Some of the predicted genes were detected for DR subpanel alone . Genes controlling hormones , auxins and gibberellins appeared important for the regulation of plant height . Many of the significant SNPs were located on chromosomes harbouring previously reported QTLs and candidate genes . The identified loci may be used for marker-assisted selection after due validation .
Hot peppers are sensitive to low temperature , and seed browning significantly reduces the fruit quality . This study aims to clarify the mechanisms of seed browning in terms of metabolite changes . Metabolites were analysed during a 30-day-storage period at 2   ° C and 10   ° C . Gamma-aminobutyric acid , tyrosine , phenylalanine , and isoleucine concentrations were significantly higher at 2   ° C storage than at 10   ° C . Reactive oxygen species ( ROS ) generation was associated with seed browning . Transcription of jasmonic acid synthesis and ROS scavenging genes were higher in hot peppers stored at 2   ° C than those stored at 10   ° C . This study elucidated the mechanisms underlying seed browning and chill damage in hot peppers during storage at low temperatures and our findings may help improve hot peppers ' quality following harvesting .
BACKGROUND : Besides fibers , cotton plants also produce a large amount of seeds with a high oil and protein content . The use of these seeds is restricted by their high contents of the terpenoid gossypol , which is harmful to humans and livestock . Using a genetic engineering approach , " Ultra-low gossypol cottonseed " ( ULGCS ) plants were produced by knocking down an enzyme that catalyzes the formation of a precursor of gossypol . This was accomplished via RNAi-mediated silencing of the target gene using a seed-specific α-globulin promotor . Since gossypol is also a crucial defense mechanism against leaf-feeding herbivores , ULGCS plants might possess lower herbivore resistance than non-engineered plants . Therefore , we tested the constitutive and inducible direct insect resistance of two ULGCS cotton lines against the African cotton leafworm , Spodoptera littoralis . RESULT : The herbivore was equally affected by both ULGCS lines and the control ( Coker 312 ) line when feeding on fully expanded true leaves from undamaged plants and plants induced by jasmonic acid . When plants were induced by caterpillar-damage , however , S. littoralis larvae performed better on the ULGCS plants . Terpenoid analyses revealed that the ULGCS lines were equally inducible as the control plants . Levels of terpenoids were always lower in one of the two lines . In the case of cotyledons , caterpillars performed better on ULGCS cotton than on conventional cotton . This was likely caused by reduced levels of gossypol in ULGCS cotyledons . CONCLUSION : Despite those effects , the insect resistance of ULGSC cotton can be considered as largely intact and the plants may , therefore , be an interesting alternative to conventional cotton varieties .
Changes in specialized metabolites were analyzed in wheat leaves inoculated with Bipolaris sorokiniana , the causal agent of spot blotch of Poaceae species . HPLC analysis detected the accumulation of six compounds in B. sorokiniana-infected leaves . Of these , we purified two compounds by silica gel and ODS column chromatography and preparative HPLC , and identified them as cinnamic acid amides , N-cinnamoyl-9-hydroxy-8-oxotryptamine and N-cinnamoyl-8-oxotryptamine , by spectroscopic analyses . The remaining four compounds were predicted to be p-coumaric acid amides of hydroxyputrescine , hydroxyagmatine , hydroxydehydroagmatine , and agmatine by mass spectrometry . The accumulation of two cinnamic acid amides was also induced by Fusarium graminearum infection , and by treatment with CuCl(2 ) , jasmonic acid , and isopentenyladenine . Antifungal activity of these amides was shown by inhibition of conidial germination and germ tube elongation of F. graminearum and Alternaria brassicicola , indicating that they act as phytoalexins . The accumulation of these amides also detected in barley leaves treated with CuCl(2 ) . We examined the accumulation of 25 phenylamides in B. sorokiniana-infected wheat leaves using LC-MS/MS . Hydroxycinnamic acid amides of tryptamine , serotonin , putrescine , and agmatine , were induced after infection with B. sorokiniana . Thus , the induced accumulation of two groups of phenylamides , cinnamic acid amides with indole amines , and p-coumaric acid amides with putrescine and agmatine related amines , represents a major metabolic response of wheat to pathogen infection .
Chemically synthesized 2-hydroxyethyl jasmonate ( HEJA ) was for the first time employed to induce the ginsenoside biosynthesis and to manipulate the product heterogeneity in plant cell cultures . The dose response and timing of HEJA elicitation were investigated in cell suspension cultures of Panax notoginseng . The optimal concentration and timing of HEJA addition for both cell growth and ginsenoside accumulation was identified to be 200 microM added on day 4 . It was interestingly found that HEJA could stimulate ginsenosides biosynthesis and change their heterogeneity more efficiently than methyl jasmonate ( MJA ) , i.e. , the total ginsenoside content and the Rb/Rg ratio increased about 60 and 30 % with HEJA elicitation than that by MJA , respectively . The activity of Rb1 biosynthetic enzyme , i.e. , UDPG-ginsenoside Rd glucosyltransferase ( UGRdGT ) , was also higher in the former case . A maximal production titer of ginsenoside Rg1 , Re , Rb1 , and Rd was 47.4+/-4.8 , 52.3+/-4.4 , 190+/-18 , and 12.1+/-2.5 mg/l with HEJA elicitation , which was about 1.3- , 1.3- , 1.7- , and 2.1-fold than that using MJA , respectively . Early signal events in plant defense response , including oxidative burst and jasmonic acid ( JA ) biosynthesis , were also examined . Levels of H2O2 and NO in medium and L-phenylalanine ammonia lyase activity in cells were not affected by addition of MJA and HEJA . On the other hand , the JA content in cells was increased with external jasmonates elicitation , and it was inhibited with the addition of JA biosynthesis inhibitors . The results suggest that oxidative burst might not be involved in the jasmonates-elicited signal transduction pathway , and MJA and HEJA may induce the ginsenoside biosynthesis via induction of endogenous JA biosynthesis and key enzymes ( such as UGRdGT ) in the ginsenoside biosynthetic pathway of P. notoginseng cells . The information is useful for hyperproduction of plant-specific heterogeneous products .
Transcriptional regulation plays a central role in plant hormone signaling . At the core of transcriptional regulation is the Mediator , an evolutionarily conserved , multisubunit complex that serves as a bridge between gene-specific transcription factors and the RNA polymerase machinery to regulate transcription . Here , we report the action mechanisms of the MEDIATOR25 ( MED25 ) subunit of the Arabidopsis thaliana Mediator in regulating jasmonate- and abscisic acid (ABA)-triggered gene transcription . We show that during jasmonate signaling , MED25 physically associates with the basic helix-loop-helix transcription factor MYC2 in promoter regions of MYC2 target genes and exerts a positive effect on MYC2-regulated gene transcription . We also show that MED25 physically associates with the basic Leu zipper transcription factor ABA-INSENSITIVE5 ( ABI5 ) in promoter regions of ABI5 target genes and shows a negative effect on ABI5-regulated gene transcription . Our results reveal that underlying the distinct effects of MED25 on jasmonate and ABA signaling , the interaction mechanisms of MED25 with MYC2 and ABI5 are different . These results highlight that the MED25 subunit of the Arabidopsis Mediator regulates a wide range of signaling pathways through selectively interacting with specific transcription factors .
Potential of MoSM1 , encoding for a cerato-platanin protein from Magnaporthe oryzae , in improvement of rice disease resistance was examined . Transient expression of MoSM1 in rice leaves initiated hypersensitive response and upregulated expression of defense genes . When transiently expressed in tobacco leaves , MoSM1 targeted to plasma membrane . The MoSM1-overexpressing ( MoSM1-OE ) transgenic rice lines showed an improved resistance , as revealed by the reduced disease severity and decreased in planta pathogen growth , against 2 strains belonging to two different races of M. oryzae , causing blast disease , and against 2 strains of Xanthomonas oryzae pv . oryzae , causing bacterial leaf blight disease . However , no alteration in resistance to sheath blight disease was observed in MoSM1-OE lines . The MoSM1-OE plants contained elevated levels of salicylic acid ( SA ) and jasmonic acid ( JA ) and constitutively activated the expression of SA and JA signaling-related regulatory and defense genes . Furthermore , the MoSM1-OE plants had no effect on drought and salt stress tolerance and on grain yield . We conclude that MoSM1 confers a broad-spectrum resistance against different pathogens through modulating SA- and JA-mediated signaling pathways without any penalty on abiotic stress tolerance and grain yield , providing a promising potential for application of MoSM1 in improvement of disease resistance in crops .