Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Provincial Key Laboratory of Applied Botany, Botanical Garden, Chinese Academy of Sciences, Guangzhou, South China, 510650, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Plant Mol Biol. 2020 Oct;104(3):249-261. doi: 10.1007/s11103-020-01039-2. Epub 2020 Jul 26.
Secondary cell wall not only provides rigidity and mechanical resistance to plants, but also has a large impact on plant growth and adaptation to environments. Biosynthesis of secondary cell wall is regulated by a complicated signaling transduction network; however, it is still unclear how the transcriptional regulation of secondary cell wall biosynthesis works at the molecular level. Here, we report in rice that OVATE family proteins 6 (OsOFP6) is a positive regulator in modulating expression of the genes related to biosynthesis of the secondary cell wall. Transgenic plants with knock-down of OsOFP6 by RNA interference showed increased leaf angle, which resulted from the thinner secondary cell wall with reduced amounts of cellulose and lignin, whilst overexpression of OsOFP6 in rice led to the thinker secondary cell wall with increased lignin content. Protein-protein interaction analysis revealed that OsOFP6 interacts with Oryza sativa homeobox 15 (OSH15), a class I KNOX protein. The interaction of OsOFP6 and OSH15 enhanced the transcriptional activity of OSH15 which binds to the promoter of OsIRX9 (Oryza sativa IRREGULAR XYLEM 9). Taken together, our study provides insights into the function of OsOFP6 in regulating leaf angle and the control of biosynthesis of secondary cell wall.
次生细胞壁不仅为植物提供了刚性和机械抗性，而且对植物的生长和适应环境也有很大的影响。次生细胞壁的生物合成受复杂的信号转导网络调控；然而，次生细胞壁生物合成的转录调控如何在分子水平上发挥作用仍不清楚。在这里，我们在水稻中报告称，卵形家族蛋白 6（OsOFP6）是调节与次生细胞壁生物合成相关基因表达的正调控因子。通过 RNA 干扰敲低 OsOFP6 的转基因植物表现出增加的叶角，这是由于次生细胞壁变薄，纤维素和木质素减少所致，而在水稻中过表达 OsOFP6 导致次生细胞壁变厚，木质素含量增加。蛋白质-蛋白质相互作用分析表明，OsOFP6 与水稻同源异型框 15（OSH15）相互作用，OSH15 是一类 KNOX 蛋白。OsOFP6 与 OSH15 的相互作用增强了 OSH15 的转录活性，OSH15 结合到 OsIRX9（Oryza sativa IRREGULAR XYLEM 9）的启动子上。总之，我们的研究提供了关于 OsOFP6 调节叶角和次生细胞壁生物合成控制的功能的见解。
