Marcos Ruth, Izquierdo Yovanny, Vellosillo Tamara, Kulasekaran Satish, Cascón Tomás, Hamberg Mats, Castresana Carmen
Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.).
Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas, Cantoblanco, E-28049 Madrid, Spain (R.M., Y.I., T.V., S.K., T.C., C.C.);Division of Physiological Chemistry II, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, S-171 77 Stockholm, Sweden (M.H.); andEnergy Biosciences Institute and Plant and Microbial Biology Department, University of California, Berkeley, California 94720 (T.V.)
Plant Physiol. 2015 Nov;169(3):2324-34. doi: 10.1104/pp.15.00992. Epub 2015 Sep 28.
The oxylipins, a large family of oxygenated lipid derivatives, regulate plant development and immunity. Two members of the 9-lipoxygenase (9-LOX) oxylipin pathway, 9-hydroxyoctadecatrienoic acid and 9-ketooctadecatrienoic acid, control root development and plant defense. Studies in Arabidopsis (Arabidopsis thaliana) using a series of 9-hydroxyoctadecatrienoic acid- and 9-ketooctadecatrienoic acid-insensitive nonresponding to oxylipins (noxy) mutants showed the importance of the cell wall as a 9-LOX-induced defense component and the participation of NOXY proteins in signaling cell wall damage. Here, we examined 9-LOX signaling using the mutants lox1lox5, which lacks 9-LOX activity, and noxy2-2, which shows oxylipin insensitivity and mitochondrial dysfunction. Mutants in brassinosteroids (BRs), a class of plant hormones necessary for normal plant growth and the control of cell wall integrity, were also analyzed. Several lines of evidence indicated that 9-LOX-derived oxylipins induce BR synthesis and signaling to activate cell wall-based responses such as callose deposition and that constitutive activation of BR signaling in bri1-EMS-suppressor 1-D (bes1-D) plants enhances this response. We found that constitutive BR signaling in bes1-D and brassinolide-resistant 1-1D (bzr1-1D) mutants conferred resistance to Pseudomonas syringae. bes1-D and bzr1-1D showed increased resistance to Golovinomyces cichoracearum, an obligate biotrophic fungus that penetrates the cell wall for successful infection, whereas susceptibility was enhanced in lox1lox5 and noxy2-2. Our results indicate a sequential action of 9-LOX and BR signaling in activating cell wall-based defense, and this response prevents pathogen infection. These results show interaction between the 9-LOX and BR pathways and help to clarify their role in modulating plant defense.
氧脂素是一大类氧化脂质衍生物，可调节植物发育和免疫。9-脂氧合酶（9-LOX）氧脂素途径的两个成员，9-羟基十八碳三烯酸和9-氧代十八碳三烯酸，控制根系发育和植物防御。在拟南芥中使用一系列对9-羟基十八碳三烯酸和9-氧代十八碳三烯酸不敏感的氧脂素无反应（noxy）突变体进行的研究表明，细胞壁作为9-LOX诱导的防御成分的重要性以及NOXY蛋白在细胞壁损伤信号传导中的参与。在这里，我们使用缺乏9-LOX活性的突变体lox1lox5和表现出氧脂素不敏感性和线粒体功能障碍的noxy2-2来研究9-LOX信号传导。还分析了油菜素类固醇（BRs）的突变体，油菜素类固醇是一类正常植物生长和细胞壁完整性控制所必需的植物激素。几条证据表明，9-LOX衍生 的氧脂素诱导BR合成和信号传导，以激活基于细胞壁的反应，如胼胝质沉积，并且在bri1-EMS抑制子1-D（bes1-D）植物中BR信号传导的组成型激活增强了这种反应。我们发现bes1-D和油菜素内酯抗性1-1D（bzr1-1D）突变体中的组成型BR信号传导赋予了对丁香假单胞菌的抗性。bes1-D和bzr1-1D对菊苣白粉菌表现出增强的抗性，菊苣白粉菌是一种专性活体营养真菌，可穿透细胞壁以成功感染，而lox1lox5和noxy2-2中的易感性增强。我们的结果表明9-LOX和BR信号传导在激活基于细胞壁的防御中具有顺序作用，并且这种反应可防止病原体感染。这些结果显示了9-LOX和BR途径之间的相互作用，并有助于阐明它们在调节植物防御中的作用。
