Abstract
In suspension-cultured rice cells, production of phytoalexins such as momilactones and phytocassanes is induced by a chitin elicitor. On the other hand, we reported phytocassanes is specifically induced by cholic acid in rice plants. However, the mechanisms of specific production of phytocassanes by cholic acid remains unknown. In this study, using LC-MS/MS, we found production of phytocassanes was induced by cholic acid in suspension-cultured rice cells as well as rice plants. We also examined by qRT-PCR expression of the diterpene cyclase genes OsCyc2 and OsDTC1 involved in production of phytocassanes and the diterpene cyclase genes OsCyc1 and OsKS4 involved in production of momilactones in the rice cells treated with cholic acid, and found the mRNA levels of OsCyc2 were much higher than those of the other three genes. These results strongly suggest specific expression of OsCyc2 is one of the reasons cholic acid specifically induces production of phytocassanes.
