Overexpression of CRK4, the cysteine-rich receptor-like protein kinase of Arabidopsis, regulates the resistance to abiotic stress and abscisic acid responses

Receptor-like kinases (RLKs) are known to regulate plant growth, cell differentiation, and defense mechanisms. Cysteine-rich receptor-like protein kinases (CRKs) are a subfamily of RLKs with more than 40 members. In this study, we found that overexpressing CRK4 in Arabidopsis enhances abiotic tolerance to salinity and drought stress. We constructed a CRK4-overexpressed pCB302ES plasmid, transformed it into Arabidopsis and evaluated the insertion site of the transgene. The CRK4-overexpressed line was selected for molecular analyses, including western blotting and flanking T-DNA sequencing. In pots treated with either 200 mM NaCl or dryness, the CRK4-overexpressed line showed higher resistance than the wild-type Columbia-0 (Col-0). The expression levels of DREB2B, RAB18, and RD29B genes associated with plant stress, were lower than those of wild-type Col-0. In addition, ABF1 and abscisic-acid-responsive element-binding factor 1 expression levels increased in CRK4-overexpressed transgenic Arabidopsis. Furthermore, in an abscisic acid (ABA)-containing medium, CRK4-overexpressed transgenic Arabidopsis and wild-type Col-0 showed different root development patterns. Our results indicate that CRK4 modulates the ABA-signaling pathway and responds to salt and drought stress in Arabidopsis. This study helps elucidate the correlation between the ABA and CRK4 genes.