Cloning, Characterization, and Expression Analysis of Eight Stress-Related NAC Genes in Tartary Buckwheat

Plant-specific NAC (NAM, ATAF1/2, and CUC2) transcription factors (TFs) play important roles in various stress responses. However, the characteristics and functions of NAC TFs in Tartary buckwheat [Fagopyrum tataricum (L.) Gaertn.], an important pseudocereal crop that is strongly adapted to growth in adverse environments, have not been investigated. Here, eight NAC-like genes, termed FtNAC2 through FtNAC9, were isolated and characterized from Tartary buckwheat. Amino acid sequence alignment analysis demonstrated that all the FtNAC proteins contain typical NAM domain of the NAC TFs family in the N terminus. Phylogenetic analysis showed that the eight FtNAC TFs were assigned to three abiotic stress-related functional subgroups. To investigate their roles in response to stresses, the relative expression levels of FtNAC genes were analyzed under abiotic stresses (salt, drought, cold, and ultraviolet B) and exogenous phytohormones (abscisic acid, methyl jasmonate, and salicylic acid) treatments. All the FtNAC genes responded to one or more treatments, among which FtNAC4 and FtNAC7 showed >20-fold upregulation of messenger RNA levels in response to salt, drought, abscisic acid, and salicylic acid treatments. The expression analysis of the NAC gene family in Tartary buckwheat under abiotic stress open the way to further investigate the molecular mechanism of NAC-dependent transcriptional control of stress response.