Abstract
Momilactones and phytocassanes are major phytoalexins in rice. We showed that biosynthetic genes for momilactones and phytocassanes are respectively clustered on rice chromosome 4 and chromosome 2, and that an elicitor-inducible bZIP transcription factor, OsTGAP1, is involved in the regulation of the expression of biosynthetic genes for diterpenoid phytoalexins. Here we performed microarray analysis using OsTGAP1 over-expressing rice cells. As a result, 1352 genes were up-regulated more than 2-fold in OsTGAP1 over-expressing cells compared to wild-type cells without elicitor treatment. Moreover, 1539 and 1267 genes were up-regulated 6 h and 24 h after elicitor treatment, respectively. We performed hierarchical clustering of gene expression of these up-regulated genes in OsTGAP1 over-expressing cells. We focused on one clade that contains biosynthetic genes for diterpenoid phytoalexins. There were PR10 genes and chitinase genes in this clade, and these genes were respectively clusterd. Now, we are performing the expression analysis of these genes, and searches for the OsTGAP1-binding sites in the promoter region of genes up-regulated in over-expressing cells by ChIP analysis.
