Identification and expression analyses of the NAC transcription factor family in Spartina alterniflora.

As a coastal halophyte, Spartina alterniflora has high salt tolerance. However, the mechanism at the molecular level has not been widely studied due to the absence of a reference genome. The proteins of NAC families are plant-specific transcription factors that regulate the growth, development and stress response in plants. To identify the NAC family and explore the relationship between NAC proteins and the growth, development and stress response of Spatina alterniflora, full-length transcriptome data of Spartina alterniflora by the third generation sequencing technology was used as reference sequences in this study to blast with the NAC protein sequences from Oryza sativa, Arabidopsis thaliana and Zea mays. Finally, 62 SaNAC proteins were found in Spartina alterniflora by deep analysis on conserved domains. Then we analyzed sequence alignment, evolution, motif prediction, homology comparison, subcellular localization, tissue and abiotic stress-induced gene differential expression profile on the NAC family members in Spartina alterniflora. As a result, all SaNAC proteins were found containing a conserved NAM domain and having certain evolutionary similarity with rice; two family proteins, SaNAC9 and SaNAC49, were expressed in the nucleus; moreover, SaNAC genes were identified to have distinct expressional profiles in different tissues and stress response of Spartina alterniflora. These results indicated the SaNAC transcription factor family not only had conserved functional domains but also played important role in the regulation of growth, development and abiotic stress response.