title: Role of chloroplast trienoic fatty acids in plant disease defense responses.
abstract: Trienoic fatty acids (TAs) are the major polyunsaturated fatty acid species in the membrane lipids in plant cells. TAs are crucial for the adaptation to abiotic stresses, especially low- or high-temperature stress. We show that TAs in chloroplast membrane lipids are involved in defense responses against avirulent bacterial pathogens. Avirulent pathogen invasion of plants induces a transient production of reactive oxygen intermediates (ROI), programmed cell death and subsequent disease resistance. The Arabidopsis fad7fad8 mutation, which prevents the synthesis of TAs in chloroplast lipids, caused the reduction in ROI accumulation in leaves inoculated with Pseudomonas syringae pv. tomato DC3000 (avrRpm1). Linolenic acid, the most abundant TA, activated the NADPH oxidase that is responsible for ROI generation. TAs were transferred from chloroplast lipids to extrachloroplast lipids coincident with ROI accumulation after inoculation with Pst DC3000 (avrRpm1). Furthermore, the fad7fad8 mutant exhibited reduced cell death and was compromised in its resistance to several avirulent P. syringae strains. These results suggest that TAs derived from chloroplast lipids play an important role in the regulation of plant defense responses.
authors.affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yaeno
authors.forename: Osamu
authors.initials: O
authors.lastname: Matsuda
authors.forename: Koh
authors.initials: K
authors.lastname: Iba
mesh_terms: D017360:Arabidopsis / Q000737:chemistry* / Q000235:genetics / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000737:chemistry*; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D019255:NADPH Oxidases / Q000378:metabolism; D010935:Plant Diseases; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D044224:Pseudomonas syringae / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D013997:Time Factors
chemical_list: D029681:Arabidopsis Proteins; D005227:Fatty Acids; D017382:Reactive Oxygen Species; D044943:Fatty Acid Desaturases; C084083:Fad7 protein, Arabidopsis; D019255:NADPH Oxidases