9--Epoxycarotenoid Dioxygenase 3 Regulates Plant Growth and Enhances Multi-Abiotic Stress Tolerance in Rice.

Although abscisic acid (ABA) is an important hormone that regulates seed dormancy, stomatal closure, plant development, as well as responses to environmental stimuli, the physiological mechanisms of ABA response to multiple stress in rice remain poorly understood. In the ABA biosynthetic pathway, 9--epoxycarotenoid dioxygenase (NCED) is the key rate-limiting enzyme. Here, we report important functions of in multi-abiotic stress tolerance in rice. The is constitutively expressed in various tissues under normal condition, Its expression is highly induced by NaCl, PEG, and HO stress, suggesting the roles for in response to the multi-abiotic stress tolerance in rice. Compared with wild-type plants, mutants had earlier seed germination, longer post-germination seedling growth, increased sensitivity to water stress and HO stress and increased stomata aperture under water stress and delayed leaf senescence. Further analysis found that mutants contained lower ABA content compared with wild-type plants, overexpression of in transgenic plants could enhance water stress tolerance, promote leaf senescence and increase ABA content. We conclude that mediates seed dormancy, plant growth, abiotic stress tolerance, and leaf senescence by regulating ABA biosynthesis in rice; and may provide a new strategy for improving the quality of crop.