Overexpression of the receptor-like kinase gene OsNRRB enhances drought-stress tolerance in rice

Receptor-like kinases (RLKs) play essential roles in plant growth, development and responses to environmental stresses. Here, we report that a putative RLK gene OsNRRB (Os10g40100.2), which encodes OsNRRB protein with a kinase domain and a U-box domain, is cloned and characterized in rice (Oryza sativa L.). Tissue-specific expression of OsNRRB tested by qRT-PCR and promoter-GUS assays shows that OsNRRB is widely expressed in rice, including internodes, roots, leaves and developing seeds. Expression profile analysis showed that OsNRRB had different transcriptional responses to drought, salt and oxidative (H2O2) stresses, as well as ABA, SA and GA3 treatments. Furthermore, OsNRRB protein is located at the surface of protoplast cells by transient expressing OsNRRB-GFP (green fluorescent protein) fusion construct in rice protoplasts. Moreover, the transgenic seedlings with overexpressed OsNRRB show better tolerance to drought stress compared to wild-type seedlings. On the contrary, the RNAi transgenic seedlings are more sensitive to drought stress. OsNRRB may positively regulate drought stress tolerance through upregulating these stress-responsive genes in rice. Indeed, the expression of stress-responsive genes of OsbZIP23, OsDREB2A, OsP5CS and OsLea3 are upregulated by overexpression of OsNRRB, which in turn increasing drought tolerance in rice.