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Light induces jasmonate‐isoleucine conjugation via OsJAR1 ‐dependent and ‐independent pathways in rice
Author(s) -
SVYATYNA KATHARINA,
JIKUMARU YUSUKE,
BRENDEL RITA,
REICHELT MICHAEL,
MITHÖFER AXEL,
TAKANO MAKOTO,
KAMIYA YUJI,
NICK PETER,
RIEMANN MICHAEL
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12201
Subject(s) - jasmonic acid , jasmonate , coleoptile , mutant , photomorphogenesis , biochemistry , enzyme , amino acid , methyl jasmonate , isoleucine , coronatine , biology , chemistry , arabidopsis , gene , leucine
The bioactive form of jasmonate is the conjugate of the amino acid isoleucine ( I le) with jasmonic acid ( JA ), which is biosynthesized in a reaction catalysed by the GH 3 enzyme JASMONATE RESISTANT 1 ( JAR 1). We examined the biochemical properties of OsJAR1 and its involvement in photomorphogenesis of rice ( O ryza sativa ). Os JAR 1 has a similar substrate specificities as its orthologue in A rabidopsis . However, osjar1 loss‐of‐function mutants did not show as severe coleoptile phenotypes as the JA ‐deficient mutants coleoptile photomorphogenesis 2 ( cpm2 ) and hebiba , which develop long coleoptiles in all light qualities we examined. Analysis of hormonal contents in the young seedling stage revealed that osjar1 mutants are still able to synthesize JA ‐ I le conjugate in response to blue light, suggesting that a redundantly active enzyme can conjugate JA and I le in rice seedlings. A good candidate for this enzyme is OsJAR2 , which was found to be able to catalyse the conjugation of JA with I le as well as with some additional amino acids. In contrast, if plants in the vegetative stage were mechanically wounded, the content of JA ‐ I le was severely reduced in osjar1 , demonstrating that OsJAR1 is the most important JA ‐ I le conjugating enzyme in the wounding response during the vegetative stage.