Soil salinization represents one of the primary abiotic stresses threatening global agricultural sustainability, impacting approximately 77 million hectares of arable land. Climate change, particularly global warming, has further intensified its adverse effects. Consequently, understanding the mechanisms underlying crop salt tolerance and enhancing this tolerance are crucial for promoting agricultural sustainability. Previous studies have indicated that the MPK signaling cascade plays a pivotal role in plants' responses to salt stress; however, the specific mechanisms remain largely unexplored and warrant further investigation at the molecular level.
The study identified ZmMPK3 as a positive regulator of the response to salt stress. In comparison to wild-type plants, mutants deficient in ZmMPK3 exhibited significantly greater growth inhibition when subjected to salt stress. Subsequent investigations revealed that ZmGRF1, a growth regulator, operates downstream of ZmMPK3 to modulate maize's response to saline environments. Under salt stress, the kinase activity of ZmMPK3 increases, leading to the phosphorylation of ZmGRF1 at threonine 32, which enhances its protein stability. Further analysis showed that this module does not regulate ion transport but instead promotes maize growth under salt stress by controlling the expression of genes related to cell proliferation.
Collectively, this study reports the mechanism by which the ZmMPK3-ZmGRF1 module promotes maize growth under salt stress by enhancing cell proliferation, providing potential genetic targets for developing salt-tolerant maize varieties.
Science Bulletin