The sucrose non-fermenting 1-related protein kinase SAPK2 enhances rice yield under drought conditions

Abstract Background: Drought stress is an important factor limiting crop productivity worldwide. Rice is critical for food security because it is consumed by more than half of the global population. Thus, enhancing the drought tolerance of rice is crucial for ensuring the production of this important crop can satisfy the demands of future generations.Results: Compared with wild-type plants, the sapk2 rice mutant lines were shorter and produced fewer grains per panicle and smaller grains. Subsequent analyses suggested that SAPK2 considerably influences the nitrate, phosphorus, and potassium contents of rice grains. The examination of rice seedling growth and development under nutrient-deprived conditions (−K, −N, and −P) proved that SAPK2 can significantly affect rice seedling growth and root development in hydroponic cultures lacking N and K+. Moreover, the NO3− influx rate and nitrate concentration of the analyzed plant materials indicated that SAPK2 promotes nitrate uptake and assimilation and influences the number of tillers and the number of grains per panicle by regulating nitrate-related transporters.Conclusion: These results suggest that SAPK2 is a key target gene for rice breeders aiming to increase yield.