Genome-Wide Identification of BjNCED Gene Family and Expression Analysis in Response to ABA, Salt, and Low-Temperature Stresses in Brassica juncea

NCED proteins play a critical role in drought, salt, and cold stress responses through ABA biosynthesis in plants. However, little information is currently available regarding the NCED gene family in Brassica species. Twenty-six putative BjNCED genes were identified in the genome of Brassica juncea, and found to be distributed on 15 chromosomes. Phylogenetic analysis suggested that these members could be classified into six subfamilies. The putative cis-elements were identified in the promoter regions of these BjNCED genes, and thought to be related to phytohormones, light, and abiotic stress responses. qRT-PCR analysis of five genes (BjNCED1, BjNCED4, BjNCED7, BjNCED16 and BjNCED18) revealed that, under salt stress, BjNCED16 and BjNCED18 showed transient induction, whereas exogenous ABA produced gene-specific and time-dependent expression patterns, including pronounced induction of BjNCED16 at 24 h. Low-temperature treatment strongly induced four of the five examined genes at 6 h. Analysis of the BjNCED genes in this study provides a valuable foundation for future investigations into the functional roles of the BjNCED family in response to growth, development and stress.