光敏色素B介导光信号影响水稻的脱落酸途径

Abstract

Several evidences revealed the interaction between phytochrome-mediated light signals and plant hormones abscisic acid (ABA) pathway in Arabidopsis . However, interaction between ABA signaling and phytochrome-mediated light signaling in mediating rice growth and development remain unclear. In the present study, we analyzed effects of PhyB -mediated light signals on ABA metabolism and ABA responses using rice wild type (WT) and the phyB mutant. It was observed that transcript levels of ABA biosynthetic genes (including OsNCED1 , OsNCED2 , OsNCED3 and OsNCED4 ) were higher in the phyB mutant than those in WT, whereas transcript level of ABA deactivating gene OsABA8OX1 was lower in the phyB mutant than that in WT, which probably contributed to the relatively high ABA content in the phyB mutant. ABA treatment inhibited germination of rice seeds grown either in the dark or under light. However, inhibitory effects of ABA treatment on seed germination were more obvious in phyB mutants relative to that in WT when seeds were grown under light conditions, suggesting that PhyB -mediated light signals attenuated the inhibitory effects triggered by ABA. Meantime, we compared the expression patterns of genes related to seed germination in WT and the phyB mutant grown in the medium with or without ABA. It was deduced that these genes is unlikely to contribute for the promotive effects of phyB-mediated light signals on seed germination. In addition, ABA treatment inhibited growth of both above-ground part and seminal root in rice seedlings. PhyB -mediated light signals did not affect the ABA-induced inhibition of above-ground part growth, but negatively regulate the inhibition of root growth. Taken together, our results suggest that PhyB -mediated light signals negatively regulate ABA accumulation and ABA responses in rice. This work reveals the influence of PhyB -mediated light signals on ABA pathway, which lays the foundation for dissecting the molecular mechanism of coordinated regulation of rice development by light and ABA in rice.