Overexpression of RCc3 improves root system architecture and enhances salt tolerance in rice.

Root system architecture represents an underexplored target for improving global crop yields. In this study, we investigated the biological role of the rice root-specific gene RCc3 in improving root growth and responses to abiotic stress by overexpressing RCc3 in rice plants. RCc3 was induced by osmotic and heat stress. RCc3 overexpression produced pleiotropic phenotypes of improved root system architecture, including increased growth of primary root, adventitious roots and lateral roots at the seedling stage. Further study indicated that auxin accumulation in the root was increased through auxin local biosynthesis and polar auxin transport in RCc3 overexpression lines. At maturity, the plant height and panicle traits were also significantly enhanced in overexpression plants. Under osmotic and heat stress conditions, the root and shoot growth were less severely inhibited in RCc3 overexpressing transgenic plants than that in wild-type plants, and the transcript levels of abiotic stress-related genes were significantly increased. Moreover, overexpression of RCc3 remarkably enhanced the tolerance to salt stress, with the elevated activities of antioxidant enzymes. Taken together, the data showed that RCc3 overexpression can improve rice root system, promote plant growth, and enhance plant tolerance to salt stress.