9-Lipoxygenase-derived oxylipins activate brassinosteroid signaling to promote cell wall-based defense and limit pathogen infection

Abstract

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 acidand 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.

Role of Jasmonic Acid Pathway in Tomato Plant-Pseudomonas syringae Interaction

“…Moreover, OPDA confers resistance of Arabidopsis plants against different pathogens in the absence of JA/JA-Ile [8,13], while rice mutants deficient in OPDA showed altered defense against the blast fungus Magnaporthe oryzae [14]. Recent studies have also suggested that OPDA is involved in enhancing callose accumulation in host plants to limit pathogen infection [15,16].…”

Arabidopsis nonresponding to oxylipins locus NOXY7 encodes a yeast GCN1 homolog that mediates noncanonical translation regulation and stress adaptation

“…Several studies have documented the importance of the 9-LOX pathway in regulation of lateral root development and activating defence against virulent Pseudomonas and pest attack (Hwang & Hwang, 2010;López et al, 2011;Montillet et al, 2013;Nalam, Keeretaweep, Sarowar, & Shah, 2012;Vellosillo et al, 2007;Vicente et al, 2012). Studies using nonresponding to oxylipins (noxy) mutants, which have an impaired 9-LOX signalling pathway, also showed the relevance of the cell wall and mitochondria as components of 9-LOXinduced defence (Marcos et al, 2015;Vellosillo et al, 2013).…”

12-Oxo-Phytodienoic Acid Acts as a Regulator of Maize Defense against Corn Leaf Aphid

“…As mentioned before, insects release salivary secretions while feeding, which could potentially activate wound-induced signaling molecules, such as OPDA, and trigger the downstream defenses in plants (Park et al, 2013;Bosch et al, 2014aBosch et al, , 2014bGuo et al, 2014;López-Galiano et al, 2017). More recent studies have suggested that oxylipins, a large family of oxidized lipids including OPDA, are involved in enhancing callose accumulation in host plants to limit pathogen infection (Marcos et al, 2015;Scalschi et al, 2015), which is also a potential defense mechanism utilized by plants to disrupt aphid colonization.…”