Genome-wide identification, evolution and expression analysis of NAC gene family under salt stress in wild emmer wheat (Triticum dicoccoides. L)

The NAC transcription factor (TF) family is one of the largest plant-specific gene families, playing the vital roles in plant growth and development as well as stress response. Although it has been extensively characterized in many plants, the significance of NAC family in wild emmer wheat is not well understood up to now. Here, a total of 200 NAC transcription factors were identified in wild emmer (TdNACs) through a genome-search method, which were classified into 12 subfamilies based on phylogenetic relationship. And the members in the subfamily shared similar exon-intron structure and conversed domain organization. Collinearity analysis revealed that segmental duplication and polyploidization contributed mainly to the expansion of TdNACs. Furthermore, the genetic variations of TdNACs were investigated using the re-sequencing data and genetic bottleneck has occurred on NAC genes when wild emmer domesticated to cultivated emmer wheat. Finally, the expression patterns of these TdNACs were investigated using RNA-seq data of the salt-tolerant genotype under salt stress to obtain salt-responsive TdNACs, and 10 out of which were further validated using QPCR analysis. This study provided the targets for further functional study of TdNAC genes, and also contributed to mine novel genes for improving the salt tolerance in wheat and other crops.