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OsTGAP1 is responsible for JA‐inducible diterpenoid phytoalexin biosynthesis in rice roots with biological impacts on allelopathic interaction
Author(s) -
Yoshida Yuri,
Miyamoto Koji,
Yamane Hisakazu,
Nishizawa Yoko,
Minami Eiichi,
Nojiri Hideaki,
Okada Kazunori
Publication year - 2017
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/ppl.12638
Subject(s) - allelopathy , biology , gene knockdown , gene , biosynthesis , transcription factor , jasmonic acid , phytoalexin , oryza sativa , biochemistry , arabidopsis , microbiology and biotechnology , botany , germination , mutant , resveratrol
Phytocassanes and momilactones are known as major diterpenoid phytoalexins (DPs), characterized by abundant production and antimicrobial activity, and their biosynthetic genes are clustered in rice genomes. The basic leucine zipper transcription factor OsTGAP1 is known to act as a regulator of the coordinated production of DPs in cultured rice cells, but in planta functions of OsTGAP1 remain largely unknown. Here, we present evidence on the biological function of OsTGAP1 in planta. In wild‐type plants, OsTGAP1 is abundantly expressed in roots compared with that in shoots. Moreover, the inductive expression of OsTGAP1 under jasmonic acid (JA) treatment was only observed in a root‐specific manner consistent with the JA‐inducible expressions of DP biosynthetic genes in roots. In reverse genetic approaches on OsTGAP1 ‐overexpressing and OsTGAP1 ‐knockdown plants, expressions of the biosynthetic genes relevant for DP accumulation were found to be remarkably increased and decreased, respectively. Reporter analysis in planta revealed that OsTGAP1 activated the promoters of OsDXS3 and momilactone biosynthetic gene OsKSL4 , presumably through binding to the TGACGT motif. Furthermore, cocultivation experiments with barnyard grass suggested that the allelopathic effect of knockdown and overexpression of OsTGAP1 was significantly changed compared with the controls. These results demonstrate that OsTGAP1 positively regulates DP accumulation via the transcriptional regulation of DP biosynthetic genes in rice roots, and this is indispensable for maintaining allelopathic interactions with paddy weeds by regulating the production of specialized metabolites like momilactones.