Characterization of six novel NAC genes and their responses to abiotic stresses in Gossypium hirsutum L.

The NAC (NAM, ATAF1, -2, and CUC2) gene family encodes plant-specific transcription factors that play a role in stress response. From this gene family, we isolated six full-length, intact putative transcription factors from Gossypium hirsutum L. (GhNAC1–GhNAC6). All six have conserved intron–exon structure, although they differ in intron length and chromosomal location. The predicted proteins, GhNAC1–GhNAC6, are similar in sequence, especially in the NAC domain. All GhNAC genes were highly expressed in leaves while they had little to no expression in stems, roots and 7-day-post-anthesis fibers. Based on real-time quantitative RT-PCR, the genes were differentially regulated under drought, high salt, cold and/or ABA (abscisic acid) conditions. This first report on NAC domain transcription factors in cotton (Gossypium spp.) aids in both the specific understanding the GhNACs’ roles as regulators of stress stimuli and other physiological processes in cotton as well as the general understanding of plant signal transduction pathways.