Variation of diterpenoid phytoalexin oryzalexin A production in cultivated and wild rice

Publication date: October 2019Source: Phytochemistry, Volume 166Author(s): Keisuke Kariya, Koichi Murata, Yu Kokubo, Naoki Ube, Kotomi Ueno, Yukinori Yabuta, Masayoshi Teraishi, Yutaka Okumoto, Naoki Mori, Atsushi IshiharaAbstractRice (Oryza sativa) leaves accumulate phytoalexins in response to pathogen attack. The major phytoalexins in rice are diterpenoids such as oryzalexins, momilactones, and phytocassanes. We measured the amount of oryzalexin A in leaves irradiated by UV light, treated with jasmonic acid, or inoculated with conidia of Bipolaris oryzae in the japonica cultivar Nipponbare and the indica cultivar Kasalath. Nipponbare leaves accumulated oryzalexin A at a high concentration, but Kasalath leaves did not. The locus responsible for this difference was mapped using backcrossed inbred lines and chromosome substitution lines. A region on Chr. 12 containing the KSL10 gene was responsible for the deficiency in oryzalexin A in the Kasalath cultivar. The amount of KSL10 transcript increased in Nipponbare leaves but not in Kasalath leaves in response to UV light irradiation, indicating that the suppressed expression of KSL10 caused the deficiency of oryzalexin A in Kasalath. We analyzed oryzalexin A accumulation in UV light-irradiated leaves of cultivars in the world rice core collection. There were cultivars that accumulated oryzalexin A and those that did not, and both of these chemotypes were found in japonica and indica subspecies. Furthermore, these chemotypes were...

Source: Phytochemistry - July 13, 2019 Category: Chemistry Source Type: research