Genome wide analysis of the NAC transcription factor family in Chinese cabbage to elucidate responses to temperature stress

Abstract

The NAC is a large family of transcription factors with many functions, involved in developmental and physiological processes. The present study involved a comprehensive analysis of NAC family transcription factors in Chinese cabbage. A total of 188 putative NAC factors were found and identified based on genome of Chinese cabbage. These BraNAC transcription factors were classified into 18 subgroups by sequence similarity. The amino acid sequence, phylogenetic tree and conserved domain were predicted and analyzed. Three motifs in NAC proteins were discovered, which were related to NAC domain construction. The analysis results showed that the NAC factors from Chinese cabbage and Arabidopsis had high similarity. The sequences of 188 NAC genes were distributed unevenly among the 10 chromosomes of the Chinese cabbage genome. Chromosomal locations showed that chromosomal duplication might result in expansion of the NAC genes in Chinese cabbage. Seven NAC genes, chosen from seven subgroups respectively, were further tested for temperature stress responses using real-time quantitative PCR analysis. In total, seven BraNAC genes were differentially expressed under cold or heat stress treatments in the two varieties of Chinese cabbage. This study advances the functional analysis of NAC transcription factors in Brassica.