Molecular cloning and expression analysis of a stress-responsive WRKY transcription factor gene, BnWRKY57, from Brassica napus

WRKY transcription factors play important roles in regulation of various plant biological processes, including response to abiotic stresses. WRKY genes might be potential targets for transgenic breeding to enhance stress tolerance in rapeseed (Brassica napus). The present study aimed to clone and characterize WRKY57 (BnWRKY57) gene derived from B. napus and to analyze patterns of BnWRKY57 expression under drought and salt stresses in two B. napus cultivars with different levels of tolerance to drought and salt. The full-length coding region of BnWRKY57 gene with 882bp long (GenBank Accession Number: MG699908) was cloned and sequenced. BnWRKY57 gene encodes a hydrophilic polypeptide of 293 amino acids. It shared high homology with other known WRKY57s from Brassicaceae family. The promoter of BnWRKY57 gene contained cis regulatory elements involved in response to phytohormones, light, biotic and abiotic stresses suggesting this gene may play a role to modulate different signaling pathways. Real time quantitative RT-PCR analysis revealed that BnWRKY57 expression was responsive to drought and salt stresses. BnWRKY57 gene showed different expression patterns between leaves and roots and also between the B. napus cultivars under stress conditions. Overall, the findings suggest that BnWRKY57 gene may contribute to adaptive responses to drought and salt stresses in B. napus.