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Plants experience a wide range of stresses in nature, which induce extensive metabolic changes and notably the production of oxylipins. Oxylipins are structurally diverse molecules derived from lipid oxidation, that can be found free (e.g., the well-known phytohormone jasmonic acid) or esterified into complex lipids in plants. Notably, arabidopsides are oxidised galactolipids containing precursors of jasmonic acid i.e., (dinor-)12-oxphytodienoic acid as oxidised chains. While arabidopsides are known to be produced upon various stress conditions, their functions in stress responses remain unclear. They are indeed thought to possess direct functions or to act indirectly by being a storage form of free (dinor-)12-oxphytodienoic acid for fast remobilisation upon stress. 
In the first part of the present master’s thesis, 2 UHPLC-MS methods were developed and optimised for the analysis of arabidopsides and jasmonates respectively. The 5 main arabidopsides A-B-D-E-G, in addition to an internal standard for their relative quantification, were well separated and detected. Regarding jasmonates, the developed method allowed the analysis of 4 jasmonates of interest (12-oxophytodienoic acid, dinor-12-oxophytodienoic acid, jasmonic acid, jasmonoyl-isoleucine) and 3 other phytohormones (salicylic acid, indole-3-acetic acid and abscisic acid) for method versatility. Calibration curves were constructed with deuterated standards for normalised absolute quantification.
In the second part of this work, the sensitivity of both methods was assessed with plant samples that consisted of Col-0 and C24 natural accessions of Arabidopsis, displaying high versus low levels of arabidopsides respectively. They were either (1) unstressed, (2) mechanically wounded or (3) freeze-thawed. The 2 selected stresses are indeed known to induce the production of arabidopsides and jasmonates. After extraction-purification of these molecules, samples were injected with the developed UHPLC-MS methods. Results showed that all 5 arabidopsides could be quantified in all Col-0 and C24 samples, except arabidopside G in control and wounded C24. Meanwhile, 3 jasmonates out of the 4 target molecules could be quantified in stressed plant samples and the fourth one could be detected. The developed methods can therefore be used for further studies on jasmonate and arabidopside involvement in plant stress responses. An easy solution to further improve sensitivity of both methods consists in increasing the initial plant mass.
In addition to sensitivity assessment, the results obtained allowed to shed light on the interconnected production of arabidopsides and jasmonates in Arabidopsis ecotypes. Indeed, a previous study indicated that arabidopside levels are lower in C24 compared to Col-0 due to substrate competition between 2 enzymes. Here, it was further highlighted that C24 not only produces significantly less arabidopsides, but also significantly less jasmonates. These results are coherent as the biosynthesis of both arabidopsides and jasmonates relies on the same enzyme, AOS. The reduced action of AOS in C24 thus necessarily impacts them both.
In the last part of the present master’s thesis, two other stress conditions were investigated.
(i) Interestingly, phosphate deficiency was found to significantly induce the production of
arabidopsides B and D in Col-0. While this difference was not significant for arabidopside A, a similar trend could be observed. Therefore, these novel and original results strongly suggest the
involvement of arabidopsides in Arabidopsis responses to phosphate deficiency, consistent with
previous reports highlighting the production of galactolipids and jasmonates during such a stress.
Future work should be considered to further explore this first-time described phenomenon.
(ii) The inoculation of Col-0 with the bacterium Pseudomonas syringae was tested to induce a bacterial infection, which is known to result in arabidopside production. A trial-and-error approach allowed the implementation of a revised protocol, which should be further tested with an appropriate bacterial strain. Combined with the analytical methods developed for arabidopsides and jasmonates, this preliminary work will be valuable in the future to test the potential remobilisation of arabidopsides into jasmonates upon bacterial infection. Dans la nature, les plantes subissent de nombreux stress qui induisent des changements métaboliques importants et notamment la production d'oxylipines. Les oxylipines sont des molécules aux structures diverses dérivées de l'oxydation des lipides, qui peuvent être libres comme l’acide jasmonique ou estérifiées dans des lipides complexes. Ainsi, les arabidopsides sont des galactolipides dont les chaines acylées oxydées sont des précurseurs de l'acide jasmonique, l'acide (dinor-)12-oxophytodiénoïque. Bien que la production d’arabidopsides lors de divers stress soit connue, leurs fonctions précises restent indéterminées. Il est suggéré que ces molécules pourraient avoir des rôles directs ou agir de manière indirecte en servant de forme de stockage de jasmonates libres pour une remobilisation rapide.
Dans la première partie de ce travail de fin d’étude, 2 méthodes analytiques ont été développées et optimisées pour l'analyse des arabidopsides et des jasmonates par UHPLC-MS. Les 5 arabidopsides principaux (A-B-D-E-G), ainsi qu'un standard interne pour leur quantification relative, ont pu être séparés et détectés. En ce qui concerne les jasmonates, la méthode mise au point ciblait 4 jasmonates d’intérêt (acide 12-oxophytodienoïque, acide dinor-12-oxophytodienoïque, acide jasmonique, jasmonoyl-isoleucine) et 3 autres phytohormones (acide salicylique, acide indole-3-acétique et acide abscissique) afin d’obtenir une méthode polyvalente. Des courbes d'étalonnage ont été construites avec des standards internes deutérés afin de quantifier ces composés de manière absolue.
L’objectif de la deuxième partie de ce travail était de confirmer la sensibilité des deux méthodes pour le dosage des arabidopsides et des jasmonates à partir d’échantillons végétaux. Ainsi, 2 écotypes d’Arabidopsis accumulant peu (C24) ou beaucoup d’arabidopsides (Col-0) ont été utilisés. Ils ont été soit non-stressées, soit soumis à 2 stress connus pour induire la formation d’arabidopsides et de jasmonates : la blessure mécanique et la congélation-décongélation. Après l'extraction-purification de ces molécules, les échantillons ont été injectés en UHPLC-MS. Les résultats ont mis en évidence que les 5 arabidopsides ont pu être quantifiés dans tous les échantillons, excepté l'arabidopside G dans les C24 contrôles et blessées mécaniquement. De plus, 3 jasmonates ont pu être quantifiés dans les plantes stressées, tandis que le jasmonoyl-isoleucine a pu être détecté mais non quantifié. Ces 2 méthodes pourront donc être utilisées dans le futur, en sachant que leur sensibilité peut être améliorée en augmentant la quantité initiale de matériel végétal utilisée.
Outre l'évaluation de la sensibilité, les résultats obtenus ont permis de mettre en évidence la
production interconnectée d'arabidopsides et de jasmonates dans les écotypes d'Arabidopsis. En effet, une étude précédente a démontré des concentrations en arabidopsides plus faibles dans C24 par rapport à Col-0 en raison d’une compétition de substrat entre 2 enzymes. Ici, les résultats obtenus indiquent que C24 produit non seulement moins d'arabidopsides, mais aussi moins de jasmonates. Comme la biosynthèse des arabidopsides et des jasmonates repose sur l’enzyme AOS qui a une action réduite dans C24, ces résultats sont cohérents et permettent d’avoir une vue globale de ce phénomène.
Dans la troisième partie de ce travail, 2 autres conditions de stress ont été étudiées.
(i) Les résultats ont montré que, dans des conditions de carence en phosphate, la production des
arabidopsides B et D est induite de manière significative chez Col-0. Même si cette différence
n'était pas significative pour l'arabidopside A, une tendance similaire a pu être observée. Par
conséquent, ces résultats nouveaux et originaux montrent pour la première fois l'implication des
arabidopsides dans les réponses d'Arabidopsis à la carence en phosphate, en accord avec de
précédentes études sur les galactolipides et les jasmonates pendant ce stress. Des travaux futurs devraient être envisagés pour explorer davantage ce phénomène décrit pour la première fois.
(ii) Enfin, un travail préliminaire ayant pour objectif futur d’utiliser les méthodes analytiques
développées afin d’étudier la remobilisation potentielle des arabidopsides en jasmonates lors
d'une infection bactérienne a été réalisé. L’inoculation d’Arabidopsis Col-0 avec la bactérie
Pseudomonas syringae a donc été testée. Une approche par essai-erreur a permis de réviser le
protocole utilisé ; la dernière version devra être testée avec une souche bactérienne adéquate.

Arabidopsis, oxylipins, arabidopsides, jasmonates, biotic stresses, abiotic stresses --- Arabidopsis, oxylipines, arabidopsides, jasmonates, stress biotiques, stress abiotiques --- Sciences du vivant > Agriculture & agronomie --- Sciences du vivant > Biologie végétale (sciences végétales, sylviculture, mycologie...) --- Sciences du vivant > Multidisciplinaire, généralités & autres

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Phytochemistry. Phytobiochemistry --- Plant physiology. Plant biophysics --- Substance de croissance végétale --- plant growth substances --- Acide gibbérellique --- Gibberellic acid --- Cytokine --- Cytokines --- ABA --- Éthylène --- Ethylene --- Extraction --- Purification --- Classification --- classification --- Fonction physiologique --- physiological functions --- Biosynthèse --- Biosynthesis --- Semence --- Seed --- Germination --- Multiplication végétative --- Vegetative propagation --- Système racinaire --- Root systems --- Dormance --- Dormancy --- Cycle de développement --- life cycle --- Floraison --- Flowering --- Photosynthèse --- Photosynthesis --- Désherbage --- Weed control --- Jasmonate --- Jasmonates --- Auxine --- Auxins --- Brassinostéroïde --- Brassinosteroids --- Plant growth promoting substances. --- Ethylene. --- classification. --- Salicylates

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This book presents the advances in plant salinity stress and tolerance, including mechanistic insights revealed using powerful molecular tools and multi-omics and gene functions studied by genetic engineering and advanced biotechnological methods. Additionally, the use of plant growth-promoting rhizobacteria in the improvement of plant salinity tolerance and the underlying mechanisms and progress in breeding for salinity-tolerant rice are comprehensively discussed. Clearly, the published data have contributed to the significant progress in expanding our knowledge in the field of plant salinity stress and the results are valuable in developing salinity-stress-tolerant crops; in benefiting their quality and productivity; and eventually, in supporting the sustainability of the world food supply.

Research & information: general --- Biology, life sciences --- watermelon --- salt stress --- RNA-seq --- amino acids --- endocytosis --- Arabidopsis thaliana --- halophyte --- high-affinity potassium transporter (HKT) --- Na+ transporter --- salt tolerance --- Sporobolus virginicus --- aquaporins --- barley --- ion transport --- oocytes --- plasma membrane intrinsic proteins (PIPs) --- GmbZIP15 --- transcription factor --- drought stress --- soybean --- biotechnology breeding --- high-throughput sequencing --- QTLs --- rice --- halophytic wild barley --- salinity --- osmotic stress --- metabolome --- transcriptome --- ionome --- stress adaptation --- Hordeum marinum --- aquaporin --- Zygophyllum xanthoxylum --- plant growth --- abiotic stress --- sensing --- signaling --- transcription factors --- osmoregulation --- antioxidation --- ion homeostasis --- jasmonates --- jasmonate signaling pathway --- crosstalk --- exogenous jasmonate applications --- GWAS --- PGPR --- ACC deaminase --- seed priming --- IAA --- cell wall integrity --- cell wall sensor --- LRXs --- CrRLK1Ls --- Millettia pinnata --- calmodulin-like --- heterologous expression --- halophiles --- plant growth-promoting rhizobacteria (PGPR) --- RNA sequence analysis (RNA-seq) --- quantitative reverse transcriptase PCR (qRT-PCR) --- watermelon --- salt stress --- RNA-seq --- amino acids --- endocytosis --- Arabidopsis thaliana --- halophyte --- high-affinity potassium transporter (HKT) --- Na+ transporter --- salt tolerance --- Sporobolus virginicus --- aquaporins --- barley --- ion transport --- oocytes --- plasma membrane intrinsic proteins (PIPs) --- GmbZIP15 --- transcription factor --- drought stress --- soybean --- biotechnology breeding --- high-throughput sequencing --- QTLs --- rice --- halophytic wild barley --- salinity --- osmotic stress --- metabolome --- transcriptome --- ionome --- stress adaptation --- Hordeum marinum --- aquaporin --- Zygophyllum xanthoxylum --- plant growth --- abiotic stress --- sensing --- signaling --- transcription factors --- osmoregulation --- antioxidation --- ion homeostasis --- jasmonates --- jasmonate signaling pathway --- crosstalk --- exogenous jasmonate applications --- GWAS --- PGPR --- ACC deaminase --- seed priming --- IAA --- cell wall integrity --- cell wall sensor --- LRXs --- CrRLK1Ls --- Millettia pinnata --- calmodulin-like --- heterologous expression --- halophiles --- plant growth-promoting rhizobacteria (PGPR) --- RNA sequence analysis (RNA-seq) --- quantitative reverse transcriptase PCR (qRT-PCR)

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This book presents the advances in plant salinity stress and tolerance, including mechanistic insights revealed using powerful molecular tools and multi-omics and gene functions studied by genetic engineering and advanced biotechnological methods. Additionally, the use of plant growth-promoting rhizobacteria in the improvement of plant salinity tolerance and the underlying mechanisms and progress in breeding for salinity-tolerant rice are comprehensively discussed. Clearly, the published data have contributed to the significant progress in expanding our knowledge in the field of plant salinity stress and the results are valuable in developing salinity-stress-tolerant crops; in benefiting their quality and productivity; and eventually, in supporting the sustainability of the world food supply.

watermelon --- salt stress --- RNA-seq --- amino acids --- endocytosis --- Arabidopsis thaliana --- halophyte --- high-affinity potassium transporter (HKT) --- Na+ transporter --- salt tolerance --- Sporobolus virginicus --- aquaporins --- barley --- ion transport --- oocytes --- plasma membrane intrinsic proteins (PIPs) --- GmbZIP15 --- transcription factor --- drought stress --- soybean --- biotechnology breeding --- high-throughput sequencing --- QTLs --- rice --- halophytic wild barley --- salinity --- osmotic stress --- metabolome --- transcriptome --- ionome --- stress adaptation --- Hordeum marinum --- aquaporin --- Zygophyllum xanthoxylum --- plant growth --- abiotic stress --- sensing --- signaling --- transcription factors --- osmoregulation --- antioxidation --- ion homeostasis --- jasmonates --- jasmonate signaling pathway --- crosstalk --- exogenous jasmonate applications --- GWAS --- PGPR --- ACC deaminase --- seed priming --- IAA --- cell wall integrity --- cell wall sensor --- LRXs --- CrRLK1Ls --- Millettia pinnata --- calmodulin-like --- heterologous expression --- halophiles --- plant growth-promoting rhizobacteria (PGPR) --- RNA sequence analysis (RNA-seq) --- quantitative reverse transcriptase PCR (qRT-PCR) --- n/a

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The plant hormone jasmonic acid (JA) and its derivative, an amino acid conjugate of JA (jasmonoyl isoleucine, JA-Ile), are signaling compounds involved in the regulation of defense and development in plants. The number of articles studying on JA has dramatically increased since the 1990s. JA is recognized as a stress hormone that regulates the plant response to biotic stresses such as herbivore and pathogen attacks, as well as abiotic stresses such as wounding and ultraviolet radiation. Recent studies have remarkably progressed the understanding of the importance of JA in the life cycle of plants. JA is directly involved in many physiological processes, including stamen growth, senescence, and root growth. JA regulates production of various metabolites such as phytoalexins and terpenoids. Many regulatory proteins involved in JA signaling have been identified by screening for Arabidopsis mutants. However, much more remains to be learned about JA signaling in other plant species. This Special Issue, “Jasmonic Acid Pathway in Plants”, contains 5 review and 15 research articles published by field experts. These articles will help with understanding the crucial roles of JA in its response to the several environmental stresses and development in plants.

transcription factor --- n/a --- ectopic metaxylem --- elicitor --- methyl jasmonate --- salicylic acid --- multiseeded --- Panax ginseng --- tea --- heterotrimeric G proteins --- Chinese flowering cabbage --- biosynthesis --- endocytosis --- jasmonic acid signaling --- MutMap --- JA-Ile --- gibberellic acid --- nitric oxide --- abiotic stresses --- MAP kinase --- light-sensitive --- transcriptional activation --- TIFY --- JAZ repressors --- JA --- gene expression --- environmental response --- xylogenesis --- priming --- jasmonate --- circadian clock --- phylogenetic analysis --- chloroplast --- Pogostemon cablin --- albino --- antioxidant enzyme activity --- stress --- Jas domain --- Zea mays --- auxin --- PatJAZ6 --- rice bacterial blight --- Tuscan varieties --- leaf senescence --- degron --- plant development --- Camellia sinensis --- AtRGS1 --- Prunus avium --- msd --- dammarenediol synthase --- sorghum --- jasmonic acid (JA) signaling pathway --- biological function --- ABA biosynthesis --- MYB transcription factor --- ethylene --- secondary metabolite --- cytokinin --- Nicotiana plants --- grain development --- grain number --- opr3 --- stress defense --- diffusion dynamics --- proline --- crosstalk --- ROS --- bioinformatics --- adventitious rooting --- ginsenoside --- jasmonates --- quantitative proteomics --- signaling --- signal molecules --- MeJA --- hypocotyl --- lipoxygenase --- jasmonic acid --- ancestral sequences --- proteomics --- Ralstonia solanacearum --- Jasmonate-ZIM domain --- signaling pathway --- patchouli alcohol --- volatile --- rice --- ectopic protoxylem --- chlorophyll fluorescence imaging --- type III effector --- fatty acid desaturase --- salt response --- transcriptional regulators --- aroma