Academic literature on the topic 'Oxylipin pathway'
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Journal articles on the topic "Oxylipin pathway"
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Creelman, Robert A., and Rao Mulpuri. "The Oxylipin Pathway in Arabidopsis." Arabidopsis Book 1 (January 2002): e0012. http://dx.doi.org/10.1199/tab.0012.
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Edin, Matthew L., Fred B. Lih, Bruce D. Hammock, Scott Thomson, Darryl C. Zeldin, and David Bishop-Bailey. "Vascular Lipidomic Profiling of Potential Endogenous Fatty Acid PPAR Ligands Reveals the Coronary Artery as Major Producer of CYP450-Derived Epoxy Fatty Acids." Cells 9, no. 5 (April 29, 2020): 1096. http://dx.doi.org/10.3390/cells9051096.
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A number of oxylipins have been described as endogenous PPAR ligands. The very short biological half-lives of oxylipins suggest roles as autocrine or paracrine signaling molecules. While coronary arterial atherosclerosis is the root of myocardial infarction, aortic atherosclerotic plaque formation is a common readout of in vivo atherosclerosis studies in mice. Improved understanding of the compartmentalized sources of oxylipin PPAR ligands will increase our knowledge of the roles of PPAR signaling in diverse vascular tissues. Here, we performed a targeted lipidomic analysis of ex vivo-generated oxylipins from porcine aorta, coronary artery, pulmonary artery and perivascular adipose. Cyclooxygenase (COX)-derived prostanoids were the most abundant detectable oxylipin from all tissues. By contrast, the coronary artery produced significantly higher levels of oxylipins from CYP450 pathways than other tissues. The TLR4 ligand LPS induced prostanoid formation in all vascular tissue tested. The 11-HETE, 15-HETE, and 9-HODE were also induced by LPS from the aorta and pulmonary artery but not coronary artery. Epoxy fatty acid (EpFA) formation was largely unaffected by LPS. The pig CYP2J homologue CYP2J34 was expressed in porcine vascular tissue and primary coronary artery smooth muscle cells (pCASMCs) in culture. Treatment of pCASMCs with LPS induced a robust profile of pro-inflammatory target genes: TNFα, ICAM-1, VCAM-1, MCP-1 and CD40L. The soluble epoxide hydrolase inhibitor TPPU, which prevents the breakdown of endogenous CYP-derived EpFAs, significantly suppressed LPS-induced inflammatory target genes. In conclusion, PPAR-activating oxylipins are produced and regulated in a vascular site-specific manner. The CYP450 pathway is highly active in the coronary artery and capable of providing anti-inflammatory oxylipins that prevent processes of inflammatory vascular disease progression.
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Chehab, E. Wassim, John V. Perea, Banu Gopalan, Steve Theg, and Katayoon Dehesh. "Oxylipin Pathway in Rice and Arabidopsis." Journal of Integrative Plant Biology 49, no. 1 (January 2007): 43–51. http://dx.doi.org/10.1111/j.1744-7909.2006.00405.x.
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Mastrogiovanni, Mauricio, Andrés Trostchansky, Hugo Naya, Raúl Dominguez, Carla Marco, Mònica Povedano, Rubèn López-Vales, and Homero Rubbo. "HPLC-MS/MS Oxylipin Analysis of Plasma from Amyotrophic Lateral Sclerosis Patients." Biomedicines 10, no. 3 (March 15, 2022): 674. http://dx.doi.org/10.3390/biomedicines10030674.
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Oxylipins play a critical role in regulating the onset and resolution phase of inflammation. Despite inflammation is a pathological hallmark in amyotrophic lateral sclerosis (ALS), the plasma oxylipin profile of ALS patients has not been assessed yet. Herein, we develop an oxylipin profile-targeted analysis of plasma from 74 ALS patients and controls. We found a significant decrease in linoleic acid-derived oxylipins in ALS patients, including 9-hydroxy-octadecadienoic acid (9-HODE) and 13-HODE. These derivatives have been reported as important regulators of inflammation on different cell systems. In addition, some 5-lipoxygenase metabolites, such as 5-hydroxy- eicosatetraenoic acid also showed a significant decrease in ALS plasma samples. Isoprostanes of the F2α family were detected only in ALS patients but not in control samples, while the hydroxylated metabolite 11-HETE significantly decreased. Despite our effort to analyze specialized pro-resolving mediators, they were not detected in plasma samples. However, we found the levels of 14-hydroxy-docosahexaenoic acid, a marker pathway of the Maresin biosynthesis, were also reduced in ALS patients, suggesting a defective activation in the resolution programs of inflammation in ALS. We further analyze oxylipin concentration levels in plasma from ALS patients to detect correlations between these metabolites and some clinical parameters. Interestingly, we found that plasmatic levels of 13-HODE and 9-HODE positively correlate with disease duration, expressed as days since onset. In summary, we developed a method to analyze “(oxy)lipidomics” in ALS human plasma and found new profiles of metabolites and novel lipid derivatives with unknown biological activities as potential footprints of disease onset.
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Jiang, Yi, Xinlong Tang, Yali Wang, Wei Chen, Yunxing Xue, Hailong Cao, Bomin Zhang, et al. "Serum Oxylipin Profiles Identify Potential Biomarkers in Patients with Acute Aortic Dissection." Metabolites 12, no. 7 (June 23, 2022): 587. http://dx.doi.org/10.3390/metabo12070587.
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Aortic dissection (AD) is a life-threatening cardiovascular disease with a dismal prognosis. Inflammation plays an important role in AD. Oxylipins are bioactive lipids involved in the modulation of inflammation and may be involved in the pathogenesis and progression of AD. This study aims to identify possible metabolites related to AD. A total of 10 type A Aortic dissection (TAAD) patients, 10 type B Aortic dissection (TBAD) patients and 10 healthy controls were included in this study. Over 100 oxylipin species were identified and quantified by liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis. Our investigation demonstrated substantial alterations in 91 oxylipins between AD and healthy individuals. Patients with TAAD had 89 entries accessible compared to healthy controls. According to orthogonal partial least squares discriminant analysis (OPLS-DA), fitness (R2X = 0.362 and R2Y = 0.807, p = 0.03) and predictability (Q2 = 0.517, p = 0.005) are the validation parameters between the two groups. Using multivariate logistic regression, 13-HOTrE and 16(17)-EpDPE were the risk factors in the aortic patients group compared to healthy people (OR = 2.467, 95%CI:1.256–7.245, p = 0.035; OR = 0.015, 95%CI:0.0002–0.3240, p = 0.016, respectively). In KEGG enrichment of differential metabolites, the arachidonic acid metabolism pathway has the most metabolites involved. We established a diagnostic model in distinguishing between AD and healthy people. The AUC was 0.905. Oxylipins were significantly altered in AD patients, suggesting oxylipin profile is expected to exploit a novel, non-invasive, objective diagnosis for AD.
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Camera, Sylvain La, Claudine Balagué, Cornelia Göbel, Pierrette Geoffroy, Michel Legrand, Ivo Feussner, Dominique Roby, and Thierry Heitz. "The Arabidopsis Patatin-Like Protein 2 (PLP2) Plays an Essential Role in Cell Death Execution and Differentially Affects Biosynthesis of Oxylipins and Resistance to Pathogens." Molecular Plant-Microbe Interactions® 22, no. 4 (April 2009): 469–81. http://dx.doi.org/10.1094/mpmi-22-4-0469.
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We previously reported that patatin-like protein 2 (PLP2), a pathogen-induced patatin-like lipid acyl hydrolase, promotes cell death and negatively affects Arabidopsis resistance to the fungus Botrytis cinerea and to the bacteria Pseudomonas syringae. We show here that, on the contrary, PLP2 contributes to resistance to Cucumber mosaic virus, an obligate parasite inducing the hypersensitive response. These contrasted impacts on different pathosystems were also reflected by differential effects on defense gene induction. To examine a possible link between PLP2 lipolytic activity and oxylipin metabolism, gene expression profiling was performed and identified B. cinerea among these pathogens as the strongest inducer of most oxylipin biosynthetic genes. Quantitative oxylipin profiling in wild-type and PLP2-modified, Botrytis-challenged plants established the massive accumulation of oxidized fatty acid derivatives in infected leaves. Several compounds previously described as modulating plant tissue damage and issued from the α-dioxygenase pathway were found to accumulate in a PLP2-dependent manner. Finally, the contribution of PLP2 to genetically controlled cell death was evaluated using PLP2-silenced or -overexpressing plants crossed with the lesion mimic mutant vascular-associated death 1 (vad1). Phenotypic analysis of double-mutant progeny showed that PLP2 expression strongly promotes necrotic symptoms in vad1 leaves. Collectively, our data indicate that PLP2 is an integral component of the plant cell death execution machinery, possibly providing fatty acid precursors for the biosynthesis of specific oxylipins and differentially affecting resistance to pathogens with distinct lifestyles.
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Hamberg, Mats, and Harold W. Gardner. "Oxylipin pathway to jasmonates: biochemistry and biological significance." Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism 1165, no. 1 (November 1992): 1–18. http://dx.doi.org/10.1016/0005-2760(92)90069-8.
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Thompson, Maranda, Arzu Ulu, Ana G. Yuil-Valdes, Maheswari Mukherjee, Melissa Thoene, Matthew Van Ormer, Rebecca Slotkowski, et al. "Omega-6 and Omega-3 Fatty Acid-Derived Oxylipins from the Lipoxygenase Pathway in Maternal and Umbilical Cord Plasma at Delivery and Their Relationship with Infant Growth." International Journal of Molecular Sciences 23, no. 2 (January 9, 2022): 708. http://dx.doi.org/10.3390/ijms23020708.
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Omega-3 and omega-6 fatty acids are important for neonatal development and health. One mechanism by which omega-3 and omega-6 fatty acids exert their effects is through their metabolism into oxylipins and specialized pro-resolving mediators. However, the influence of oxylipins on fetal growth is not well understood. Therefore, the objective of this study was to identify oxylipins present in maternal and umbilical cord plasma and investigate their relationship with infant growth. Liquid chromatography–tandem mass spectrometry was used to quantify oxylipin levels in plasma collected at the time of delivery. Spearman’s correlations highlighted significant correlations between metabolite levels and infant growth. They were then adjusted for maternal obesity (normal body mass index (BMI: ≤30 kg/m2) vs. obese BMI (>30 kg/m2) and smoking status (never vs. current/former smoker) using linear regression modeling. A p-value < 0.05 was considered statistically significant. Our study demonstrated a diverse panel of oxylipins from the lipoxygenase pathway present at the time of delivery. In addition, both omega-3 and omega-6 oxylipins demonstrated potential influences on the birth length and weight percentiles. The oxylipins present during pregnancy may influence fetal growth and development, suggesting potential metabolites to be used as biomarkers for infant outcomes.
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Gao, Xiquan, Won-Bo Shim, Cornelia Göbel, Susan Kunze, Ivo Feussner, Robert Meeley, Peter Balint-Kurti, and Michael Kolomiets. "Disruption of a Maize 9-Lipoxygenase Results in Increased Resistance to Fungal Pathogens and Reduced Levels of Contamination with Mycotoxin Fumonisin." Molecular Plant-Microbe Interactions® 20, no. 8 (August 2007): 922–33. http://dx.doi.org/10.1094/mpmi-20-8-0922.
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Plant oxylipins, produced via the lipoxygenase (LOX) pathway, function as signals in defense and development. In fungi, oxylipins are potent regulators of mycotoxin biosynthesis and sporogenesis. Previous studies showed that plant 9-LOX-derived fatty acid hydroperoxides induce conidiation and mycotoxin production. Here, we tested the hypothesis that oxylipins produced by the maize 9-LOX pathway are required by pathogens to produce spores and mycotoxins and to successfully colonize the host. Maize mutants were generated in which the function of a 9-LOX gene, ZmLOX3, was abolished by an insertion of a Mutator transposon in its coding sequence, which resulted in reduced levels of several 9-LOX-derived hydroperoxides. Supporting our hypothesis, conidiation and production of the mycotoxin fumonisin B1 by Fusarium verticillioides were drastically reduced in kernels of the lox3 mutants compared with near-isogenic wild types. Similarly, conidia production and disease severity of anthracnose leaf blight caused by Colletotrichum graminicola were significantly reduced in the lox3 mutants. Moreover, lox3 mutants displayed increased resistance to southern leaf blight caused by Cochliobolus heterostrophus and stalk rots caused by both F. verticillioides and C. graminicola. These data strongly suggest that oxylipin metabolism mediated by a specific plant 9-LOX isoform is required for fungal pathogenesis, including disease development and production of spores and mycotoxins.
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Matsui, Kenji. "Green leaf volatiles: hydroperoxide lyase pathway of oxylipin metabolism." Current Opinion in Plant Biology 9, no. 3 (June 2006): 274–80. http://dx.doi.org/10.1016/j.pbi.2006.03.002.
Full textDissertations / Theses on the topic "Oxylipin pathway"
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Nalam, Vamsi J. "9-Lipoxygenase Oxylipin Pathway in Plant Response to Biotic Stress." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc115127/.
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The activity of plant 9-lipoxygenases (LOXs) influences the outcome of Arabidopsis thaliana interaction with pathogen and insects. Evidence provided here indicates that in Arabidopsis, 9-LOXs facilitate infestation by Myzus persicae, commonly known as the green peach aphid (GPA), a sap-sucking insect, and infection by the fungal pathogen Fusarium graminearum. in comparison to the wild-type plant, lox5 mutants, which are deficient in a 9-lipoxygenase, GPA population was smaller and the insect spent less time feeding from sieve elements and xylem, thus resulting in reduced water content and fecundity of GPA. LOX5 expression is induced rapidly in roots of GPA-infested plants. This increase in LOX5 expression is paralleled by an increase in LOX5-synthesized oxylipins in the root and petiole exudates of GPA-infested plants. Micrografting experiments demonstrated that GPA population size was smaller on plants in which the roots were of the lox5 mutant genotype. Exogenous treatment of lox5 mutant roots with 9-hydroxyoctadecanoic acid restored water content and population size of GPA on lox5 mutants. Together, these results suggest that LOX5 genotype in roots is critical for facilitating insect infestation of Arabidopsis. in Arabidopsis, 9-LOX function is also required for facilitating infection by F. graminearum, which is a leading cause of Fusarium head blight (FHB) disease in wheat and other small grain crops. Loss of LOX1 and LOX5 function resulted in enhanced resistance to F. graminearum infection. Similarly in wheat, RNA interference mediated silencing of the 9-LOX homolog TaLpx1, resulted in enhanced resistance to F. graminearum. Experiments in Arabidopsis indicate that 9-LOXs promote susceptibility to this fungus by suppressing the activation of salicylic acid-mediated defense responses that are important for basal resistance to this fungus. the lox1 and lox5 mutants were also compromised for systemic acquired resistance (SAR), an inducible defense mechanism that is systemically activated throughout a plant in response to a localized infection. the lox1 and lox5 mutants exhibited reduced cell death and delayed hypersensitive response when challenged with an avirulent strain of the bacterial pathogen Pseudomonas syringae pv tomato. LOX1 and LOX5 functions were further required for the synthesis as well as perception of a SAR-inducing activity present in petiole exudates collected from wild-type avirulent pathogen-challenged leaves. Taken together, results presented here demonstrate that 9-LOX contribute to host susceptibility as well as defense against different biotic stressors.
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Xing, Qikun. "Deciphering the oxylipin signaling pathways during defense responses in brown macroalgae." Thesis, Sorbonne université, 2021. http://www.theses.fr/2021SORUS536.
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Les oxylipines sont des composés oxygénés dérivés d'acides gras polyinsaturés (AGPI), présents chez de nombreux organismes. Chez les plantes et les animaux, ils ont des rôles signaux dans la croissance et en réponse à divers stress. Les algues brunes ont développé des voies de biosynthèse des oxylipines uniques, à partir des AGPI en C18 et C20. Cependant, le rôle et la régulation de ces voies y sont encore peu connus. Au cours de ma thèse, j'ai mené des analyses transcriptomiques à large échelle chez deux espèces d’algues brunes, Saccharina latissima et Laminaria digitata, lors d'interactions biotiques, en relation avec l'induction des voies des oxylipines. Ces analyses ont été conduites sur des algues cocultivées avec des endophytes et en réponse à l’élicitation par les oligoguluronates. Plusieurs gènes liés à la biosynthèse des oxylipines montrent des régulations différentes. Après l’élicitation, un gène codant potentiellement pour un cytochrome P450 (CYP) est surexprimé à 1 h et 12 h, suggérant une induction séquentielle des voies des oxylipines chez S. latissima. Des profilages métaboliques montrent l’accumulation précoces d’oxylipines issues de la voie des AGPI en C18 et suggèrent le rôle alternatif de composés dérivés des AGPI en C20. Enfin, le rôle biologique de plusieurs oxylipines et aldéhydes a été étudié sur la régulation de certains gènes cibles ou l'accumulation de composés putatifs de défense chez S. latissima et L. digitata. Les résultats de ces travaux ont permis de reconstruire partiellement les voies des oxylipines et de mieux comprendre leur régulation lors des réponses de défense chez les algues brunesOxylipins are oxygenated compounds derived from polyunsaturated fatty acids (PUFAs), found in many organisms. In land plants and animals, they are known to have regulating roles in growth and in response to various stresses. Brown algae have developed unique oxylipin pathways, using both C18- and C20- type PUFAs. However, the role and regulation of oxylipin pathways during defense responses are largely unclear in brown algae. In my PhD thesis, I conducted large transcriptomic analyses in order to decipher the molecular responses of two kelps species, Saccharina latissima and Laminaria digitata during biotic interactions, in relationships with the induction of oxylipin pathways. The transcriptomic analysis was performed on a kelp-endophyte co-cultivation bioassay and oligoguluronate elicitation. Among differentially expressed genes, several genes putatively involved in oxylipin pathways were identified with diverse expression patterns. During the elicitation, one putative cytochrome P450 (CYP)-encoding gene was induced at 1 h and 12 h, suggesting that oxylipin pathways in S. latissima might be induced at least two times. The result of metabolite profiling showed an early production of putative C18 oxylipins and the putative alternative role of C20 oxylipin pathways during the elicitation. Finally, the biological function of several oxylipins and aldehydes were tested on targeted gene or metabolite inductions in S. latissima and L. digitata. Altogether, these results led to the partial reconstruction of oxylipin pathways and provide a better understanding of their regulation during defense responses in kelps
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Fammartino, Alesandro. "Characterization of a tobacco divinyl ether biosynthetic pathway specifically associated with pathogenesis and defense signalling." Toulouse 3, 2007. http://www.theses.fr/2007TOU30025.
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Les oxylipines générés par la voie lipoxygénase (LOX) sont impliquées dans la défense des végétaux. Lors de l'interaction tabac/Phytophthora parasitica var. Nicotianae (Ppn) une voie 9-LOX (NtLOX1) est activée, et des plantes transgéniques antisens (AS-LOX) sont plus sensibles vis-à-vis du pathogène. Ce travail a montré que l'acide 9-hydroxyoctadécadiénoïque et les divinyl éthers (DVEs) sont induits en réponse à Ppn, et que le phénotype des AS-LOX est associé à leur absence. Une voie de synthèse DVE est proposée impliquant NtLOX1 et la DVE synthase NtDES1. Ces enzymes sont localisées dans le cytosol, et coopèrent in vitro pour produire des DVEs. Leur transcription est coordonnée et précoce chez le WT (pas chez les AS-LOX) inoculées par Ppn, et induite par des éliciteurs, l'acide jasmonique et l'éthylène, mais inhibée par l'acide salicylique. NtLOX1 et NtDES1 constituent une voie de biosynthèse 9-DVE cruciale pour la résistance aux pathogènes chez le tabacPlant oxylipins generated by the lipoxygenase (LOX) pathway are involved in defense. In the tobacco/Phytophthora parasitica var nicotianae (Ppn) interaction a 9-LOX pathway (NtLOX1) is activated, and transgenic antisense (AS-LOX) plants are more susceptible to Ppn. Here, oxylipin profiling on Ppn-inoculated WT and AS-LOX roots indicated that in WT plants, 9-hydroxyoctadecadienoic acid and divinyl ethers (DVEs) are most prominently induced, and that the phenotype of AS-LOX plants is associated to their absence. A DVE-biosynthetic pathway is proposed involving NtLOX1 and the DVE synthase NtDES1. Both enzymes localized in the cytosol and cooperated to generate DVEs from free fatty acids in vitro. Their transcription was coordinated and precocious in WT (not AS-LOX) Ppn-inoculated roots, and induced by elicitors, jasmonic acid, ethylene but inhibited by salicylic acid. NtLOX1 and NtDES1 constitute a 9-DVE biosynthetic pathway crucial for resistance to pathogens in tobacco
Book chapters on the topic "Oxylipin pathway"
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Blée, Elizabeth, and Francis Schuber. "Oxylipins in Plants: The Peroxygenase Pathway." In Plant Lipid Metabolism, 262–64. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8394-7_72.
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Brown, Robert Andrew. "The Roles of Linoleic and Alpha-linolenic Acid, Their Oxylipins and the PPAR Alpha-, Delta- and Gamma-Related Peroxisomal Pathways on Obesity in the Context of a “Western” Diet." In Omega-3 Fatty Acids, 429–49. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-40458-5_31.
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Salch, Yangkyo, David Hildebrand, Hitoshi Takamura, Harold Gardner, Thomas Simpson, and Kevan Croft. "Oxylipin Pathway in Soybeans and Its Physiological Significance." In Lipoxygenase and Lipoxygenase Pathway Enzymes, 162–75. AOCS Publishing, 1996. http://dx.doi.org/10.1201/9781439831977.ch9.
Full textReports on the topic "Oxylipin pathway"
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Brown Horowitz, Sigal, Eric L. Davis, and Axel Elling. Dissecting interactions between root-knot nematode effectors and lipid signaling involved in plant defense. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7598167.bard.
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Root-knot nematodes, Meloidogynespp., are extremely destructive pathogens with a cosmopolitan distribution and a host range that affects most crops. Safety and environmental concerns related to the toxicity of nematicides along with a lack of natural resistance sources threaten most crops in Israel and the U.S. This emphasizes the need to identify genes and signal mechanisms that could provide novel nematode control tactics and resistance breeding targets. The sedentary root-knot nematode (RKN) Meloidogynespp. secrete effectors in a spatial and temporal manner to interfere with and mimic multiple physiological and morphological mechanisms, leading to modifications and reprogramming of the host cells' functions, resulted in construction and maintenance of nematodes' feeding sites. For successful parasitism, many effectors act as immunomodulators, aimed to manipulate and suppress immune defense signaling triggered upon nematode invasion. Plant development and defense rely mainly on hormone regulation. Herein, a metabolomic profiling of oxylipins and hormones composition of tomato roots were performed using LC-MS/MS, indicating a fluctuation in oxylipins profile in a compatible interaction. Moreover, further attention was given to uncover the implication of WRKYs transcription factors in regulating nematode development. In addition, in order to identify genes that might interact with the lipidomic defense pathway induced by oxylipins, a RNAseq was performed by exposing M. javanicasecond-stage juveniles to tomato protoplast, 9-HOT and 13-KOD oxylipins. This transcriptome generated a total of 4682 differentially expressed genes (DEGs). Being interested in effectors, we seek for DEGs carrying a predicted secretion signal peptide. Among the DEGs including signal peptide, several had homology with known effectors in other nematode species, other unknown potentially secreted proteins may have a role as root-knot nematodes' effectors which might interact with lipid signaling. The molecular interaction of LOX proteins with the Cyst nematode effectors illustrate the nematode strategy in manipulating plant lipid signals. The function of several other effectors in manipulating plant defense signals, as well as lipids signals, weakening cell walls, attenuating feeding site function and development are still being studied in depth for several novel effectors. As direct outcome of this project, the accumulating findings will be utilized to improve our understanding of the mechanisms governing critical life-cycle phases of the parasitic M. incognita RKN, thereby facilitating design of effective controls based on perturbation of nematode behavior—without producing harmful side effects. The knowledge from this study will promote genome editing strategies aimed at developing nematode resistance in tomato and other nematode-susceptible crop species in Israel and the United States.
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Barg, Rivka, Kendal D. Hirschi, Avner Silber, Gozal Ben-Hayyim, Yechiam Salts, and Marla Binzel. Combining Elevated Levels of Membrane Fatty Acid Desaturation and Vacuolar H+ -pyrophosphatase Activity for Improved Drought Tolerance. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7613877.bard.
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Background to the topic: In previous works we have shown that Arabidopsis and tomato over-expressing H+-pyrophosphatase show increased tolerance to drought imposed by withholding irrigation of young plants in pots (Park et al. 2005). In addition, young tobacco plants over-expressing fatty acid desaturase 3 (OEX-FAD3) also showed increasing tolerance to drought stress (Zhang et al 2005), and similarly OEX-FAD3 young tomato plants (unpublished data from ARO), hence raising the possibility that pyramiding the two could further improve drought tolerance in tomato. Based on these findings the specific objects originally set were: 1. To analyze the impact of pyramiding transgenes for enhanced fatty acid desaturation and for elevated H+-PPase activity on tomato yielding under water deficit stress conditions. 2. To elucidate the biochemical relationship between elevated desaturation of the membrane lipids and the activities of selected vacuolar transporters in the context of drought responses. 3. To explore the S. pennellii introgression lines as alternative genetic sources for drought tolerance related to enhanced fatty acid desaturation and/or H+-PPase activity. 4. Since OEX-FAD3 increases the levels of linolenic acid which is the precursor of various oxylipins including the stress hormone Jasmonate. (JA), study of the effect of this transgene on tolerance to herbivore pests was added as additional goal. The Major conclusions, solutions, and achievements are: (1) The facts that ectopic over-expression of vacuolarH+-PPases (in line OEX-AVP1) does not change the fatty acid profile compared to the parental MoneyMaker (MM) line and that elevated level of FA desaturation (by OEX-FAD3) does not change the activity of either H+-PPase, H+-ATPaseor Ca2+ /H+ antiport, indicate that the observed increased drought tolerance reported before for increase FA desaturation in tobacco plants and increased H+PPase in tomato plants involves different mechanisms. (2) After generating hybrid lines bringing to a common genetic background (i.e. F1 hybrids between line MP-1 and MM) each of the two transgenes separately and the two transgenes together the effect of various drought stress regimes including recovery from a short and longer duration of complete water withhold as well as performance under chronic stresses imposed by reducing water supply to 75-25% of the control irrigation regime could be studied. Under all the tested conditions in Israel, for well established plants grown in 3L pots or larger, none of the transgenic lines exhibited a reproducible significantly better drought tolerance compare to the parental lines. Still, examining the performance of these hybrids under the growth practices followed in the USA is called for. (3) Young seedlings of none of the identified introgression lines including the S. pennellii homologs of two of the H+-PPase genes and one of the FAD7 genes performed better than line M82 upon irrigation withhold. However, differences in the general canopy structures between the IL lines and M82 might mask such differences if existing. (4). Over-expression of FAD3 in the background of line MP-1 was found to confer significant tolerance to three important pest insects in tomato: Bordered Straw (Heliothis peltigera), Egyptian cotton leafworm (Spodoptera littoralis) and Western Flower Thrips (Frankliniella occidentalis). Implications: Although the original hypothesis that pyramiding these two trasgenes could improve drought tolerance was not supported, the unexpected positive impact on herbivore deterring, as well as the changes in dynamics of JA biosynthesis in response to wounding and the profound changes in expression of wound response genes calls for deciphering the exact linolenic acid derived signaling molecule mediating this response. This will further facilitate breeding for herbivore pest and mechanical stress tolerance based on this pathway.