Systematic analysis of NAC transcription factors in uncovers their roles in response to Verticillium wilt.

As one of the largest plant-specific gene families, the NAC transcription factor gene family plays important roles in various plant physiological processes that are related to plant development, hormone signaling, and biotic and abiotic stresses. However, systematic investigation of the gene family in sea-island cotton ( L.) has not been reported, to date. The recent release of the complete genome sequence of sea-island cotton allowed us to perform systematic analyses of ) genes. In this study, we performed a genome-wide survey and identified 270 genes in the sea-island cotton genome. Genome mapping analysis showed that genes were unevenly distributed on 26 chromosomes. Through phylogenetic analyses of GbNACs along with their Arabidopsis counterparts, these proteins were divided into 10 groups (I-X), and each contained a different number of GbNACs with a similar gene structure and conserved motifs. One hundred and fifty-four duplicated gene pairs were identified, and almost all of them exhibited strong purifying selection during evolution. In addition, various -acting regulatory elements in genes were found to be related to major hormones, defense and stress responses. Notably, transcriptome data analyses unveiled the expression profiles of 62 genes under Verticillium wilt (VW) stress. Furthermore, the expression profiles of 15 genes tested by quantitative real-time PCR (qPCR) demonstrated that they were sensitive to methyl jasmonate (MeJA) and salicylic acid (SA) treatments and that they could be involved in pathogen-related hormone regulation. Taken together, the genome-wide identification and expression profiling pave new avenues for systematic functional analysis of candidates, which may be useful for improving cotton defense against VW.