Genome-wide characterization of cysteine-rich receptor-like kinase (CRK) gene family in rice and OsCRK26 functional analysis in response to drought stress

• Genome-wide identification and drought-responsive expression analysis of the OsCRK family. • OsCRK26 loss-of-function leads to enhanced drought sensitivity and defective stomatal closure. • OsCRK26 is localized in the endoplasmic reticulum and interacts with DCA1 for stomatal function modulation. Cysteine-rich receptor-like kinases (CRKs) are a major subfamily of receptor-like protein kinases, crucial for plant immunity and adaptation to environmental stresses. However, their comprehensive characterization in rice remains limited. In this study, we aimed to systematically characterize the OsCRK gene family in rice and elucidate their roles in stress responses. We identified 73 putative OsCRK members and categorized them into three subfamilies based on phylogenetic relationships. Cis-regulatory element analysis indicated that OsCRKs are associated with stress responses. qRT-PCR validation of six OsCRK genes showed their responsiveness to PEG6000 treatment, revealing significant repression of OsCRK26 by PEG6000 and abscisic acid treatment. Subcellular localization studies showed that OsCRK26 is localized to the endoplasmic reticulum. Functional analysis revealed that loss-of-function mutations in OsCRK26 led to reduced stomatal closure and increased water loss compared to wild type plants, resulting in heightened sensitivity to drought stress. Additionally, we found that OsCRK26 interacts with DCA1, a transcriptional co-activator involved in stomatal regulation. These findings provide a comprehensive understanding of the OsCRK gene family's function and highlight OsCRK26 as a promising candidate for improving drought resistance in rice.