Receptor-like cytoplasmic kinase OsRLCK241 functions as an important regulator of abscisic acid synthesis and response in rice

ABSTRACT As an important receptor-like kinase subfamily in plants, receptor-like cytoplasmic kinases (RLCKs), such as Oryza sativa L. (Os) RLCK241, are critical in the response to abiotic stress conditions. However, the involvement of OsRLCK241 in the abscisic acid (ABA) signal response remains unknown. In this study, we found that OsRLCK241 participates in the ABA response in rice. The results showed that OsRLCK241 transcription was notably induced by ABA in the rice shoot and root in time- and dose-dependent manners. Additionally, β-glucuronidase staining and analysis of subcellular localization demonstrated that OsRLCK241 directly responded to both ABA and salt treatments. Moreover, phenotypic and physiological analyses showed that OsRLCK241 overexpression decreased ABA sensitivity and ABA content relative to the wild-type variant (Kitaake) under salt stress, and OsRLCK241 loss-of-function variants consistently displayed the opposite ABA-sensitivity phenotype and effects on ABA content. Furthermore, OsRLCK241 overexpression or loss of function modified stomatal patterning under salt stress. Quantitative real-time PCR indicated that the expression of most ABA synthesis-related marker genes, as well as that of genes involved in ABA signal transduction, was altered in both OsRLCK241-overexpressing rice lines and loss-of-function mutants under salt stress. These results suggest that OsRLCK241 is an important regulator of ABA synthesis and response in rice and expand the understanding of plant RLCKs.