title: Methanol is an endogenous elicitor molecule for the synthesis of tryptophan and tryptophan-derived secondary metabolites upon senescence of detached rice leaves.
abstract: 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.
authors.affiliation: Department of Biotechnology, Interdisciplinary Program of Graduate School for Bioenergy and Biomaterials, Bioenergy Research Center, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Kiyoon
authors.initials: K
authors.lastname: Kang
authors.forename: Sangkyu
authors.initials: S
authors.lastname: Park
authors.forename: Uyanga
authors.initials: U
authors.lastname: Natsagdorj
authors.forename: Young Soon
authors.initials: YS
authors.lastname: Kim
authors.forename: Kyoungwhan
authors.initials: K
authors.lastname: Back
mesh_terms: D000040:Abscisic Acid; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D000432:Methanol / Q000378:metabolism*; D012275:Oryza / Q000201:enzymology*; D018515:Plant Leaves / Q000201:enzymology*; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D034622:RNA Interference; D012701:Serotonin / Q000096:biosynthesis* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014364:Tryptophan / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors; D012701:Serotonin; D000040:Abscisic Acid; D014364:Tryptophan; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; D000432:Methanol