Effects of a bile acid elicitor, cholic acid, on the biosynthesis of diterpenoid phytoalexins in suspension-cultured rice cells.
An elicitor of rice defense responses was recently isolated from human feces and was identified as cholic acid (CA). Pathogen infection in rice leaves induces phytocassanes and momilactones, both of which are major diterpenoid phytoalexins in rice, whereas CA mainly induces phytocassanes. We established a high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry protocol for the rapid and accurate quantification of phytocassanes and momilactones. Using this method, we showed that CA preferentially induced the formation of phytocassanes in suspension-cultured rice cells, while a fungal chitin oligosaccharide elicitor induced that of both phytocassanes and momilactones. We further investigated the effects of CA on the expression of diterpene cyclase genes involved in phytoalexin biosynthesis. CA induced the transcription of the genes OsCPS2 (OsCyc2) and OsKSL7 (OsDTC1), which are involved in phytocassane biosynthesis, to a greater extent than the genes OsCPS4 (OsCyc1) and OsKSL4, which are involved in momilactone biosynthesis. OsCPS2 was particularly strongly induced, suggesting that it is one of the main mechanisms by which CA induces high levels of phytocassanes.
Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Takafumi
T
Shimizu
Yusuke
Y
Jikumaru
Atsushi
A
Okada
Kazunori
K
Okada
Jinichiro
J
Koga
Kenji
K
Umemura
Eiichi
E
Minami
Naoto
N
Shibuya
Morifumi
M
Hasegawa
Osamu
O
Kodama
Hideaki
H
Nojiri
Hisakazu
H
Yamane
D001647:Bile Acids and Salts / Q000737:chemistry; D018929:Cell Culture Techniques; D019826:Cholic Acid / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D015394:Molecular Structure; D012275:Oryza / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012717:Sesquiterpenes; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D013729:Terpenes / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D000094162:Phytoalexins
D001647:Bile Acids and Salts; D010940:Plant Proteins; D012717:Sesquiterpenes; D013729:Terpenes; D019826:Cholic Acid; D000094162:Phytoalexins