slotreck/pickle huggingface dataset:
Gibberellin ( GA ) regulates various plant growth and developmental processes , but its role in pathogen attack , and especially nematode-plant interactions , still remains to be elucidated . An in-depth characterization of the role of GA in nematode infection was conducted using mutant lines of rice , chemical inhibitors , and phytohormone measurements . Our results showed that GA influences rice-Meloidogyne graminicola interactions in a concentration-dependent manner . Foliar spray of plants with a low concentration of gibberellic acid enhanced nematode infection . Biosynthetic and signaling mutants confirmed the importance of gibberellin for rice susceptibility to M.   graminicola infection . Our study also demonstrates that GA signaling suppresses jasmonate (JA)-mediated defense against M.   graminicola , and likewise the JA-induced defense against M.   graminicola requires SLENDER RICE1 (SLR1)-mediated repression of the GA pathway . In contrast to observations from other plant-pathogen interactions , GA plays a dominant role over JA in determining susceptibility to M.   graminicola in rice . This GA-induced nematode susceptibility was largely independent of auxin biosynthesis , but relied on auxin transport . In conclusion , we showed that GA-JA antagonistic crosstalk is at the forefront of the interaction between rice and M.   graminicola , and SLR1 plays a central role in the JA-mediated defense response in rice against this nematode .
Many induced responses in plants are systemic . Therefore , root-induced responses may alter leaf quality for shoot herbivores . Previously , we found that root and shoot application of jasmonic acid ( JA ) to feral Brassica oleracea both induced glucosinolates in the leaves . However , the types of glucosinolates that increased in root- and shoot induced plants were different . Here we analyse whether primary metabolites , such as sugars and amino acids , are also differentially affected . Moreover , we test whether chemical differences in root- and shoot-induced plants differentially affect growth of the generalist Mamestra brassicae and the specialist Pieris rapae . Comprehensive analysis of glucosinolates , amino acid and sugars with principal component analysis revealed that leaf chemical profiles were affected both by JA application and by the organ that was induced . Shoot-induction increased indole glucosinolates , whereas root-induction induced aliphatic glucosinolates in the leaves . Leaves of shoot-induced plants had lower total sugar and total amino acid levels , whereas in root-induced plants only total sugar levels were significantly decreased . (Iso)leucine responded significantly different from the general trend , which allowed us to discuss the potential role of Myb transcription factors which are coordinating JA-induced glucosinolate and amino acid responses in Arabidopsis thaliana . Both M. brassicae and P. rapae grew the slowest on leaves of shoot-induced plants . M. brassicae growth and survival was also reduced on root-induced plants , whereas P. rapae growth on these plants was similar to that on controls . Specialist and generalist herbivores thus are differentially affected by the chemical changes after root and shoot-JA application .
The phloem plays a crucial role in assimilate and nutrient transport , pathogen response , and plant growth and development . Yet , few species have yielded pure phloem exudate and , if proteins need to be analysed , those species may not have sequenced genomes , making identification difficult . The enrichment of Arabidopsis thaliana phloem exudate in amounts large enough to allow for metabolite and protein analysis is described . Using this method , it was possible to identify 65 proteins present in the Arabidopsis phloem exudate . The majority of these proteins could be grouped by response to pathogens , stress , or hormones , carbon metabolism , protein interaction , modification , and turnover , and transcription factors . It was also possible to detect 11 proteins that play a role in lipid/fatty acid metabolism ( aspartic protease , putative 3-β-hydroxysteroid dehydrogenase , UDP-sulphoquinovose synthase/SQD1 , lipase , PIG-P-like protein : phosphatidylinositol-N-acetylglucosaminyltransferase ) , storage ( glycine-rich protein ) , binding ( annexin , lipid-associated family protein , GRP17/oleosin ) , and/or signalling ( annexin , putative lipase , PIG-P-like protein ) . Along with putative lipid-binding proteins , several lipids and fatty acids could be identified . Only a few examples exist of lipids ( jasmonic acid , oxylipins ) or lipid-binding proteins ( DIR1 , acyl-CoA-binding protein ) in the phloem . Finding hydrophobic compounds in an aqueous environment is not without precedence in biological systems : human blood contains a variety of lipids , many of which play a significant role in human health . In blood , lipids are transported while bound to proteins . The present findings of lipids and lipid-binding proteins in phloem exudates suggest that a similar long-distance lipid signalling exists in plants and may play an important role in plant growth and development .
Plant grafting is a sequential wound healing process . However , whether wounding induces a different jasmonic acid ( JA ) response within half a day ( 12 h ) after grafting or non-grafting remains unclear . Using the tomato hypocotyl grafting method , we show that grafting alleviates the asymmetrical accumulation of JA and jasmonic acid isoleucine conjugate ( JA-Ile ) in scion and rootstock caused by wounding , and from 2 h after tomato micrografting , grafting obviously restored the level of JA-Ile in the scion and rootstock . Meanwhile , five JA-related genes , SlLOX11 , SlAOS , SlCOI1 , SlLAPA and SlJA2L , are detected and show significant changes in transcriptional expression patterns within 12 h of grafting , from asymmetrical to symmetrical , when the expression of 30 JA- and defense-related genes were analyzed . The results indicated that grafting alleviates the asymmetrical JA and defense response between scion and rootstock of the tomato hypocotyl within 12 h as induced by wounding . Moreover , we demonstrate that in the very early hours after grafting , JA-related genes may be involved in a molecular mechanism that changes asymmetrical expression as induced by wounding between scion and rootstock , thereby promoting wound healing and grafting success .
The genes of the gibberellin ( GA ) biosynthesis pathway in Gibberella fujikuroi are organized in a gene cluster consisting of at least seven genes . Here we report the cloning and characterization of smt , a gene encoding a membrane transporter of the major facilitator super-family 1 , which is located next to the GA gene cluster . Since pathway-specific transporters occur frequently in prokaryotic and fungal antibiotic and toxin clusters , smt was thought to be involved in GA secretion . The gene is expressed in mycelium grown under GA-production conditions , but not when the GA biosynthesis is repressed by high amounts of ammonium . To investigate the function of SMT , gene replacement experiments were performed . The smt-mutants did not show any reduction in the GA yield ; and gibberellic acid or its precursors did not influence the gene expression . However , sugar alcohols , such as myo-inositol , sorbitol and mannitol , induced the expression of smt . The results demonstrate that the smt gene does not play an essential role in biosynthesis and secretion of GAs in G. fujikuroi , despite the location adjacent to the GA gene cluster .
Certain plant growth promoting bacteria have ability to ameliorate abiotic and/or biotic stressors , which can be exploited to enhance plant growth and productivity of the plants under stress conditions . Therefore , the present study aimed to examine the role of a rhizospheric bacterial isolate SBP-9 isolated from Sorghum bicolor ( i ) in promoting the wheat plant growth under salinity stress , and ( ii ) in enhancing the defense response in wheat against fungal pathogen " Fusarium graminearum . " The test isolate possessed plant growth promoting ( PGP ) traits including ACC deaminase ( ACCD ) , gibberellic acid , indole acetic acid ( IAA ) , siderophore , and inorganic phosphate solubilization . Under salt ( NaCl ) stress , inoculation of this isolate to wheat plant significantly increased plant growth in terms of various growth parameters such as shoot length/root length ( 20 - 39 % ) , fresh weight/dry weight ( 28 - 42 % ) , and chlorophyll content ( 24 - 56 % ) following inoculation of test isolate SBP-9 . Bacterial inoculation decreased the level of proline , and malondialdehyde , whereas elevated the antioxidative enzymatic activities of superoxide-dismutase ( SOD ; 28 - 41 % ) , catalase ( CAT ; 24 - 56 % ) , and peroxidase ( POX ; 26 - 44 % ) . Furthermore , it also significantly decreased the Na(+ ) accumulation in both shoot and roots in the range of 25 - 32 % , and increased the K(+ ) uptake by 20 - 28 % , thereby favoring the K(+)/Na(+ ) ratio . On the other hand , the test isolate also enhanced the level of defense enzymes like β-1 , 3 glucanase , phenylalanine ammonia lyase ( PAL ) , peroxidae ( PO ) , and polyphenol oxidase ( PPO ) , which can protect plants from the infection of pathogens . The result of colonization test showed an ability of the test isolate to successfully colonize the wheat plants . These results indicate that Stenotrophomonas maltophilia SBP-9 has potential to promote the wheat growth under biotic and abiotic ( salt ) stressors directly or indirectly and can be further tested at field level for exploitation as bioinoculant .
A rapid , selective , sensitive , accurate , and inexpensive immunosensor for gibberellin acid detection was designed by coupling immunoassay with the square wave anodic stripping voltammetry ( SWASV ) technique involving copper ion labeled antigen in the competitive immunoreaction . The response signal expressed as the percentage of current reduction CR % ( y ) is linearly related to the concentration of GA ( x ) in the 1 microg/mL to approximately 150 microg/mL range with a regression equation of the form y = 0.44x + 15.59 and a correlation coefficient of 0.99 . The results of the immunosensor assay were compared with those obtained by HPLC and ELISA , which show a satisfactory agreement . The immunosensor was used to determine the GA content in the hybrid rice grain samples taken in the growing period .
Jasmonic acid is a carbocyclic fatty acid that is biosynthesized from alpha-linolenic acid in several steps . The formation of the ring structure of jasmonic acid is catalyzed by the enzyme allene oxide cyclase ( EC 5.3.99.6 ) and involves the cyclization of an unstable allene oxide into the cyclopentenone 12-oxo-10,15(Z)-phytodienoic acid . In this study , a number of allene oxides were generated , and their enzymatic and nonenzymatic cyclization into cyclopentenones was investigated . Nonenzymatic cyclization was observed with allene oxides having one pair of conjugated double bonds and an additional isolated double bond in the beta , gamma position relative to the epoxide group , i.e. , the partial structure 4,5-epoxy-1,3,7-octatriene . Enzymatic cyclization took place provided that this structural element was inserted in the fatty acid chain with its epoxide group in the n-6,7 position and the isolated double bond in the n-3 position . A number of oxygenated fatty acids having structural features in common with the natural allene oxides were tested as inhibitors of allene oxide cyclase . Fatty acids having an allene oxide structure in the n-6,7 position but lacking the double bond in the n-3 position , as well as fatty acids having a saturated epoxide group in the n-6,7 position , served as competitive inhibitors of the enzyme . Data on the substrate specificity of allene oxide synthase ( EC 4.2.1.92 ) from corn seeds indicated that fatty acid hydroperoxides with a double bond at n-3 and with the hydroperoxide function at n-6 exhibit the highest affinity but the slowest reaction velocity .
Calmodulin ( CaM ) plays an important role in sensing and transducing changes in cellular Ca2 + concentration in response to several biotic and abiotic stresses . Although CaM is implicated in plant-pathogen interactions , its molecular targets and their role in defense signaling pathway(s ) are poorly understood . To elucidate the signaling pathways that link CaM to defense responses , we screened a cDNA library constructed from bean leaves undergoing a hypersensitive response ( HR ) with radiolabeled CaM isoforms . A total of 26 putative CBPs were identified . Sequencing of the cDNAs revealed that they represent 8 different genes . They are homologues of previously identified CaM-binding proteins ( CBPs ) in other systems . However , some CBPs are novel members of known CBP families . The proteins encoded by these clones bound CaM in a Ca2 + -dependent manner . To determine if these CBPs are involved in plant defense responses , we analyzed their expression in bean leaves inoculated with compatible , incompatible and nonpathogenic bacterial strains . Expression of three CBPs including an isoform of cyclic nucleotide-gated channels ( PvCNGC-A ) and two hypothetical proteins ( PvCBP60-C and PvCBP60-D ) was induced whereas the expression of two other isoforms of CNGCs ( PvCNGC-B and PvCNGC-C ) was repressed in response to incompatible pathogens . The expression of the rest , a small auxin up RNA ( PvSAUR1 ) and two hypothetical proteins ( PvCBP60-A and PvCBP60-B ) , was not changed . The expression of most of the pathogen-regulated genes was also affected by salicylic acid , jasmonic acid , hydrogen peroxide and a fungal elicitor , which are known to induce defense responses . Our results strongly suggest that at least five bean CBPs are involved in plant defense responses .
Biotic and abiotic stress induces the formation of galactolipids esterified with the phytohormones 12-oxo-phytodienoic acid ( OPDA ) and dinor-oxo-phytodienoic acid ( dnOPDA ) in Arabidopsis thaliana . The biosynthetic pathways of free (dn)OPDA is well described , but it is unclear how they are incorporated into galactolipids . We herein show that (dn)OPDA containing lipids are formed rapidly after disruption of cellular integrity in leaf tissue . Five minutes after freeze-thawing , 60 - 70 % of the trienoic acids esterified to chloroplast galactolipids are converted to (dn)OPDA . Stable isotope labeling with (18)O-water provides strong evidence for that the fatty acids remain attached to galactolipids during the enzymatic conversion to (dn)OPDA .
Selected strains of nonpathogenic rhizobacteria can reduce disease in foliar tissues through the induction of a defense state known as induced systemic resistance ( ISR ) . Compared with the large body of information on ISR in dicotyledonous plants , little is known about the mechanisms underlying rhizobacteria-induced resistance in cereal crops . Here , we demonstrate the ability of Pseudomonas fluorescens WCS374r to trigger ISR in rice ( Oryza sativa ) against the leaf blast pathogen Magnaporthe oryzae . Using salicylic acid (SA)-nonaccumulating NahG rice , an ethylene-insensitive OsEIN2 antisense line , and the jasmonate-deficient mutant hebiba , we show that this WCS374r-induced resistance is regulated by an SA-independent but jasmonic acid/ethylene-modulated signal transduction pathway . Bacterial mutant analysis uncovered a pseudobactin-type siderophore as the crucial determinant responsible for ISR elicitation . Root application of WCS374r-derived pseudobactin ( Psb374 ) primed naive leaves for accelerated expression of a pronounced multifaceted defense response , consisting of rapid recruitment of phenolic compounds at sites of pathogen entry , concerted expression of a diverse set of structural defenses , and a timely hyperinduction of hydrogen peroxide formation putatively driving cell wall fortification . Exogenous SA application alleviated this Psb374-modulated defense priming , while Psb374 pretreatment antagonized infection-induced transcription of SA-responsive PR genes , suggesting that the Psb374- and SA-modulated signaling pathways are mutually antagonistic . Interestingly , in sharp contrast to WCS374r-mediated ISR , chemical induction of blast resistance by the SA analog benzothiadiazole was independent of jasmonic acid/ethylene signaling and involved the potentiation of SA-responsive gene expression . Together , these results offer novel insights into the signaling circuitry governing induced resistance against M. oryzae and suggest that rice is endowed with multiple blast-effective resistance pathways .
When plants are attacked by pathogens , they defend themselves with an arsenal of defence mechanisms , both passive and active . The active defence responses , which require de novo protein synthesis , are regulated through a complex and interconnected network of signalling pathways that mainly involve three molecules , salicylic acid ( SA ) , jasmonic acid ( JA ) , and ethylene ( ET ) , and which results in the synthesis of pathogenesis-related ( PR ) proteins . Microbe or elicitor-induced signal transduction pathways lead to ( i ) the reinforcement of cell walls and lignification , ( ii ) the production of antimicrobial metabolites ( phytoalexins ) , and ( iii ) the production of reactive oxygen species ( ROS ) and reactive nitrogen species ( RNS ) . Among the proteins induced during the host plant defence , class III plant peroxidases ( EC 1.11.1.7 ; hydrogen donor : H(2)O(2 ) oxidoreductase , Prxs ) are well known . They belong to a large multigene family , and participate in a broad range of physiological processes , such as lignin and suberin formation , cross-linking of cell wall components , and synthesis of phytoalexins , or participate in the metabolism of ROS and RNS , both switching on the hypersensitive response ( HR ) , a form of programmed host cell death at the infection site associated with limited pathogen development . The present review focuses on these plant defence reactions in which Prxs are directly or indirectly involved , and ends with the signalling pathways , which regulate Prx gene expression during plant defence . How they are integrated within the complex network of defence responses of any host plant cell will be the cornerstone of future research .
Staphylococcus aureus is a ubiquitous gram-positive bacterium that can cause superficial to serious systemic infections in animals and humans . Here we report the development of a plant infection model to study the pathogenesis of this bacterium . Three global regulatory mutants , RN6911 ( agr- ) , ALC 488 ( sarA- ) ALC 842 ( sarA-/agr- ) and an alpha-toxin mutant defective in biofilm formation ( DU1090 ) which are attenuated in animal pathogenesis , were also attenuated in their ability to infect plants , suggesting that these regulators that mediate synthesis of virulence factors essential for animal pathogenesis are also required for plant pathogenesis . Further , using Arabidopsis plants altered in defense responses such as the transgenic lines NahG [ defective in salicylic acid ( SA ) accumulation ] , and 35S-LOX2- ( defective in jasmonic acid production and hyper-accumulator of SA ) , and mutants ics1 ( depleted in SA accumulation ) , and npr1 - 1 ( non-expressor of pathogenesis-related protein ) we show that resistance of Arabidopsis to typical plant pathogens and the animal pathogen S. aureus is conserved and is mediated by SA . The data presented here suggest that Arabidopsis thaliana resistance to S. aureus is mediated either by a direct effect of SA on the pathogen , specifically one that affects the attachment/aggregate formation on the root surface and reduces the pathogen 's virulence , or by SA-dependent , NPR1-independent host responses .
Plants coordinate and tightly regulate pathogen defense by the mostly antagonistic salicylate (SA)- and jasmonate (JA)-mediated signaling pathways . Here , we show that the previously uncharacterized glucosyltransferase UGT76B1 is a novel player in this SA-JA signaling crosstalk . UGT76B1 was selected as the top stress-induced isoform among all 122 members of the Arabidopsis thaliana UGT family . Loss of UGT76B1 function leads to enhanced resistance to the biotrophic pathogen Pseudomonas syringae and accelerated senescence but increased susceptibility toward necrotrophic Alternaria brassicicola . This is accompanied by constitutively elevated SA levels and SA-related marker gene expression , whereas JA-dependent markers are repressed . Conversely , UGT76B1 overexpression has the opposite effect . Thus , UGT76B1 attenuates SA-dependent plant defense in the absence of infection , promotes the JA response , and delays senescence . The ugt76b1 phenotypes were SA dependent , whereas UGT76B1 overexpression indicated that this gene possibly also has a direct effect on the JA pathway . Nontargeted metabolomic analysis of UGT76B1 knockout and overexpression lines using ultra-high-resolution mass spectrometry and activity assays with the recombinant enzyme led to the ab initio identification of isoleucic acid ( 2-hydroxy-3-methyl-pentanoic acid ) as a substrate of UGT76B1 . Exogenously applied isoleucic acid increased resistance against P. syringae infection . These findings indicate a novel link between amino acid-related molecules and plant defense that is mediated by small-molecule glucosylation .
Brassinosteroids ( BRs ) are a group of naturally occurring plant steroidal compounds with wide-ranging biological activity that offer the unique possibility of increasing crop yields through both changing plant metabolism and protecting plants from environmental stresses . In recent years , genetic and biochemical studies have established an essential role for BRs in plant development , and on this basis BRs have been given the stature of a phytohormone . A remarkable feature of BRs is their potential to increase resistance in plants to a wide spectrum of stresses , such as low and high temperatures , drought , high salt , and pathogen attack . Despite this , only a few studies aimed at understanding the mechanism by which BRs promote stress resistance have been undertaken . Studies of the BR signaling pathway and BR gene-regulating properties indicate that there is cross-talk between BRs and other hormones , including those with established roles in plant defense responses such as abscisic acid , jasmonic acid , and ethylene . Recent studies aimed at understanding how BRs modulate stress responses suggest that complex molecular changes underlie BR-induced stress tolerance in plants . Analyses of these changes should generate exciting results in the future and clarify whether the ability of BRs to increase plant resistance to a range of stresses lies in the complex interactions of BRs with other hormones . Future studies should also elucidate if BRI1 , an essential component of the BR receptor , directly participates in stress response signaling through interactions with ligands and proteins involved in plant defense responses .