title: OsJAR1 contributes mainly to biosynthesis of the stress-induced jasmonoyl-isoleucine involved in defense responses in rice.
abstract: Jasmonate plays key roles in plant growth and stress responses, as in defense against pathogen attack. Jasmonoyl-isoleucine (JA-Ile), a major active form of jasmonates, is thought to play a pivotal role in plant defense responses, but the involvement of JA-Ile in rice defense responses, including phytoalexin production, remains largely unknown. Here we found that OsJAR1 contributes mainly to stress-induced JA-Ile production by the use of an osjar1 Tos17 mutant. The osjar1 mutant was impaired in JA-induced expression of JA-responsive genes and phytoalexin production, and these defects were restored genetically. Endogenous JA-Ile was indispensable to the production of a flavonoid phytoalexin, sakuranetin, but not to that of diterpenoid phytoalexins in response to heavy metal stress and the rice blast fungus. The osjar1 mutant was also found to be more susceptible to the blast fungus than the parental wild type. These results suggest that JA-Ile production makes a contribution to rice defense responses with a great impact on stress-induced sakuranetin production.
authors.affiliation: Biotechnology Research Center, The University of Tokyo, Tokyo 113-8657, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Shimizu
authors.forename: Koji
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Kanako
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Eiichi
authors.initials: E
authors.lastname: Minami
authors.forename: Yoko
authors.initials: Y
authors.lastname: Nishizawa
authors.forename: Moritoshi
authors.initials: M
authors.lastname: Iino
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nojiri
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Yamane
authors.forename: Kazunori
authors.initials: K
authors.lastname: Okada
mesh_terms: D003517:Cyclopentanes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007532:Isoleucine / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism; D020082:Magnaporthe / Q000502:physiology; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology* / Q000502:physiology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D012717:Sesquiterpenes / Q000378:metabolism; D013312:Stress, Physiological; D000094162:Phytoalexins
chemical_list: D003517:Cyclopentanes; D010940:Plant Proteins; D012717:Sesquiterpenes; C532883:jasmonoyl-isoleucine; D007532:Isoleucine; D000094162:Phytoalexins