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Methanol is an endogenous elicitor molecule for the synthesis of tryptophan and tryptophan‐derived secondary metabolites upon senescence of detached rice leaves
Author(s) -
Kang Kiyoon,
Park Sangkyu,
Natsagdorj Uyanga,
Kim Young Soon,
Back Kyoungwhan
Publication year - 2011
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2011.04486.x
Subject(s) - elicitor , endogeny , tryptophan , biosynthesis , biochemistry , abscisic acid , chemistry , wrky protein domain , anthranilic acid , senescence , enzyme , secondary metabolite , kynurenine , metabolite , gene expression , biology , gene , microbiology and biotechnology , transcriptome , amino acid
Summary During senescence of detached rice leaves, tryptophan (Trp) and Trp‐derived secondary metabolites such as serotonin and 4‐coumaroylserotonin accumulated in concert with methanol (MeOH) production. This senescence‐induced MeOH induction was closely associated with levels of pectin methylesterase ( PME ) 1 mRNA and PME enzyme activity. Exogenous challenge of detached rice leaves with 1% MeOH accelerated Trp and serotonin biosynthesis with induction of the corresponding genes. No other solvents, including ethanol, resulted in a Trp‐inducing effect. This MeOH‐induced Trp synthesis was positively regulated by abscisic acid but negatively regulated by cytokinin, suggesting hormonal involvement in the action of MeOH. Endogenous overproduction or suppression of MeOH either by PME1 overexpression or RNA interference (RNAi) gene silencing revealed that PME1 overexpressing lines produced twofold higher Trp levels with elevated Trp biosynthetic gene expression, whereas RNAi lines showed twofold reduction in Trp level in healthy control rice leaves, suggesting that MeOH acts as an endogenous elicitor to enhance Trp biosynthesis. Among many transcription factors induced following MeOH treatment, the WRKY family showed significant induction patterns, of which WRKY14 appeared to play a key regulatory role in MeOH‐induced Trp and Trp‐derived secondary metabolite biosynthesis.