Identification of WRKY transcription factors responding to abiotic stresses in Brassica napus L.

Main conclusion A total of 278 BnWRKYs were identified and analyzed. Ectopic expression of BnWRKY149 and BnWRKY217 suggests that they function in the ABA signaling pathway. WRKY transcription factors play an important role in plant development, however, their function in Brassica napus L. abiotic stress response is still unclear. In this study, a total of 278 BnWRKY transcription factors were identified from the B. napus genome data, and they were subsequently distributed in three main groups. The protein motifs and classification of BnWRKY transcription factors were analyzed, and the locations of their corresponding encoding genes were mapped on the chromosomes of B. napus. Transcriptome analysis of rapeseed seedlings exposed to drought, salt, heat, cold and abscisic acid treatment revealed that 99 BnWRKYs responded to at least one of these stresses. The expression profiles of 12 BnWRKYs were examined with qPCR and the result coincided with RNA-seq analysis. Two genes of interest, BnWRKY149 and BnWRKY217 (homologs of AtWRKY40), were overexpressed in Arabidopsis, and the corresponding proteins were located to the nucleus. Transgene plants of BnWRKY149 and BnWRKY217 were less sensitive to ABA than Arabidopsis Col-0 plants, suggesting they might play important roles in the responses of rapeseed to abiotic stress.