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Diterpenoid phytoalexin factor, a bHLH transcription factor, plays a central role in the biosynthesis of diterpenoid phytoalexins in rice
Author(s) -
Yamamura Chihiro,
Mizutani Emi,
Okada Kazunori,
Nakagawa Hitoshi,
Fukushima Setsuko,
Tanaka Atsunori,
Maeda Satoru,
Kamakura Takashi,
Yamane Hisakazu,
Takatsuji Hiroshi,
Mori Masaki
Publication year - 2015
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/tpj.13065
Subject(s) - phytoalexin , transcription factor , biology , biosynthesis , transcription (linguistics) , oryza sativa , promoter , gene , biochemistry , microbiology and biotechnology , gene expression , resveratrol , linguistics , philosophy
Summary Rice ( Oryza sativa ) produces diterpenoid phytoalexins ( DP s), momilactones and phytocassanes as major phytoalexins. Accumulation of DP s is induced in rice by blast fungus infection, copper chloride or UV light. Here, we describe a rice transcription factor named diterpenoid phytoalexin factor ( DPF ), which is a basic helix‐loop‐helix ( bHLH ) transcription factor. The gene encoding DPF is expressed mainly in roots and panicles, and is inducible in leaves by blast infection, copper chloride or UV . Expression of all DP biosynthetic genes and accumulation of momilactones and phytocassanes were remarkably increased and decreased in DPF over‐expressing and DPF knockdown rice, respectively. These results clearly demonstrated that DPF positively regulates DP accumulation via transcriptional regulation of DP biosynthetic genes, and plays a central role in the biosynthesis of DP s in rice. Furthermore, DPF activated the promoters of COPALYL DIPHOSPHATE SYNTHASE 2 ( CPS 2 ) and CYTOCHROME P450 MONOOXYGENASE 99A2 ( CYP 99A2 ), whose products are implicated in the biosynthesis of phytocassanes and momilactones, respectively. Mutations in the N‐boxes in the CPS 2 upstream region, to which several animal bHLH transcription factors bind, decreased CPS 2 transcription, indicating that DPF positively regulates CPS 2 transcription through the N‐boxes. In addition, DPF partly regulates CYP 99A2 through the N‐box. This study demonstrates that DPF acts as a master transcription factor in DP biosynthesis.