Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China.
College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China.
J Exp Bot. 2020 Jan 23;71(3):1160-1170. doi: 10.1093/jxb/erz491.
Phytohormones are crucial in the regulation of plant growth and development, and in responses to adverse environments. Multiple cytochrome P450 monooxygenases (CYP450s) are involved in the biosynthesis and catabolism of phytohormones. Here, we report that a CYP450 member of the CYP71 clan in rice, OsCYP71D8L, participates in the control of multiple agronomic traits and abiotic stress responses by affecting gibberellin (GA) and cytokinin (CK) homeostasis. The gain-of-function mutant cyp71d8l and transgenic plants overexpressing CYP71D8L (CYP71D8L-OE) display similar phenotypes compared to the wild-type (WT), including dwarfed plants, reduced panicle length, reduced grain number per panicle, and decreased levels of endogenous GAs. Moreover, the dwarfed plant trait and the less-developed roots of CYP71D8L-OE and cyp71d8l seedlings could be rescued by application of GA3 or the CK biosynthetic inhibitor lovastatin, and exacerbated by application of the synthetic CK 6-BA. Importantly, CYP71D8L-OE and cyp71d8l seedlings maintained high chlorophyll contents and low levels of reactive oxygen species, and showed enhanced tolerance to drought and salt stress compared with the WT. Thus, our results suggest that OsCYP71D8L plays important roles in regulating rice growth and stress responses by coordinating the homeostasis of GAs and CKs, and it may therefore be a useful target for engineering stress-tolerant rice varieties.
植物激素在植物生长发育和应对不利环境的过程中起着至关重要的作用。多种细胞色素 P450 单加氧酶（CYP450s）参与了植物激素的生物合成和分解代谢。在这里，我们报告说，水稻 CYP71 家族的 CYP71D8L 是一个 CYP450 成员，它通过影响赤霉素（GA）和细胞分裂素（CK）的动态平衡来参与控制多个农艺性状和非生物胁迫反应。功能获得型突变体 cyp71d8l 和过表达 CYP71D8L（CYP71D8L-OE）的转基因植物与野生型（WT）相比表现出相似的表型，包括矮化植株、穗长缩短、穗粒数减少和内源 GA 水平降低。此外，CYP71D8L-OE 和 cyp71d8l 幼苗的矮化植株特征和发育不良的根系可以通过施加 GA3 或 CK 生物合成抑制剂 lovastatin 得到挽救，而施加合成 CK 6-BA 则会加剧这种情况。重要的是，与 WT 相比，CYP71D8L-OE 和 cyp71d8l 幼苗保持较高的叶绿素含量和较低的活性氧水平，并表现出对干旱和盐胁迫的增强耐受性。因此，我们的研究结果表明，OsCYP71D8L 通过协调 GA 和 CK 的动态平衡，在调节水稻生长和应激反应方面发挥着重要作用，因此可能是培育耐应激水稻品种的有用目标。
