OsCYP71D8L as a key regulator involved in growth and stress response by mediating gibberellins homeostasis in rice

Phytohormones are pivotal in the regulation of plant growth and development, and acclimation to adverse environments. Multiple cytochrome P450 monooxygenases (CYP450s) are involved in the biosynthesis and catabolism of phytohormones. Here, we reported that a CYP450 member of CYP71 clan, OsCYP71D8L, participated in the control of multiple agronomic traits and abiotic stress responses by affecting gibberellin (GA) and cytokinin (CK) homeostasis in rice. We found that its gain-of-function mutant (cyp71d8l) and transgenic plants overexpressing OsCYP71D8L (OsCYP71D8L-OE) displayed similar phenotypes including dwarfed plant, reduced panicle length and grain number per panicle, and their endogenous GAs levels were notably decreased as compared to wild type (WT), respectively. Moreover, the dwarfed plant and less developed root of OsCYP71D8L-OE and cyp71d8l seedlings could be rescued by exogenous GA3 and lovastatin, but exacerbated by exogenous 6-BA. Importantly, OsCYP71D8L-OE and cyp71d8l seedlings maintained high chlorophyll contents and low reactive oxygen species level, and showed the enhanced tolerance to drought and salt stress compared with WT. Thus, our results suggest that OsCYP71D8L plays important roles in regulating rice growth and stress responses by coordinating GAs and CKs homeostasis, and it is useful to engineer stress-tolerant rice.