Title:
Transcriptional regulation of the biosynthesis of specialized metabolites in rice
Contents：
Plants attacked by pathogenic microorganisms respond with a variety of defensive reactions, including the production of an antifungal substance, phytoalexins. Momilactones and phytocassanes are major diterpenoid phytoalexins and sakuranetin is the only flavonoid phytoalexin in rice. Biosynthetic genes for momilactones and phytocassanes are clustered on rice chromosome 4 and chromosome 2, respectively. We found that an elicitor-inducible bZIP transcription factor, OsTGAP1, is involved in the coordinated regulation of the expression of biosynthetic genes for the diterpenoid phytoalexins in the clusters and the upstream methylerythritol phosphate pathway genes. ChIP-seq analysis showed that OsTGAP1 predominantly bound to the intergenic regions and outside of the phytoalexin biosynthetic gene clusters and did not bind to the upstream regions of majority of the biosynthetic gene. This suggests that expression of the genes in the clusters is not necessarily regulated by direct binding of OsTGAP1 to the target gene promoters and that there might be as-yet-unidentified mechanisms to regulate the coordinated expression of the clustered and unclustered genes for the biosynthesis of diterpenoid phytoalexins. Transcriptinal networks leading to phytoalexin production in rice will be summarized in this talk. Sakuranetin, the other type of phytoalexin, is also expected to be a potential pharmaceutical substance for human health. Recently, we identified a gene for rice narigenin 7-O-methyltransferase, OsNOMT, involved in the final steps of sakuranetin biosynthesis. This finding enables us to generate sakuranetin overproducing plants and to produce this useful compound in a heterologously expressed NOMT protein. Potential applications of our findings on rice defence responses in the production of useful materials will be introduced in this talk.
Lecturer：
associate professor Kazunori Okada（University of Tokyo）
Biography：
Dr. Kazunori Okada is an associate professor of Biotechnology Research Center, The University of Tokyo. He was a Special Postdoctoral Researchers in RIKEN from 1998 to 2000, and then he was an assistant professor of Tokyo Gakugei University from 2000 to 2003. He moved to University of Tokyo as an assistant professor. He received an Encouraging Award of JSBBA in 2010.
Time:
Sept.24th, 2015 10:00am
Venue:
Room A435, College of Agriculture and Biotechnology. Zijingang Campus
Host:
Prof. Fan Longjiang