抄録
In rice, the production of phytoalexins are induced in suspension-cultured rice cells treated with a chitin oligosaccharide elicitor and leaves treated with a heavy metal elicitor, CuCl_2. In this study, elicitor-induced phytoalexin production in rice cells were compared between a normal-type rice and cpm2, a photomorphogenesis mutant that is thought to be JA-deficient, to investigate the roles of JA in the elicitor-induced phytoalexin production. Quantification of JA and phytoalexins was performed by LC-MS/MS throughout this study. In cpm2 cells, the chitin elicitor-induced JA production was severely suppressed. It was also shown by microarray analysis that the expression of 16% of elicitor-induced genes was repressed in cpm2 cells. However, genes involved in diterpenoid phytoalexin biosynthesis were not repressed in cpm2. In fact, there was no significant difference in the chitin elicitor-induced diterpenoid phytoalexin production between the normal-type rice and cpm2 cells. With regard to the flavonoid type phytoalexin sakuranetin, quantification was performed using CuCl_2-treated rice leaves as plant materials, indicating that the production of sakuranetin was suppressed in cpm2 leaves treated with CuCl_2. However, the suppressed production of sakuranetin in cpm2 leaves was recovered by the addition of JA. These results strongly suggest that JA is essential for the production of sakuranetin but not for the production of diterpenoid phytoalexins.
