SRWD: a novel WD40 protein subfamily regulated by salt stress in rice (OryzasativaL.).

By analysis with microarray data, we found that a gene encoding a novel protein containing five WD40 repeats, was regulated by salt stress in rice and named as SRWD1 (Salt responsive WD40 protein 1). By database searching, additional four SRWD1-like genes (SRWD2-SRWD5) were found in rice genome, and these five SRWD genes formed a novel WD40 subfamily. Phylogenetic analysis showed that plant SRWD proteins divided into four groups. The significant functional divergences during SRWD evolution were found. The tissue-specific and salt responsive expression profiling for SRWD genes was investigated based on microarray data. It was found that all five SRWD genes in rice were regulated by salt stress. Further, we found that SRWD1 was regulated with different patterns by salt stress in two rice cultivars responding differently to salt stress. Our study correlates WD40 proteins with salt stress in plants and provides fundamental information for the further investigation of plant SRWD proteins.