TsNAC1 Is a Key Transcription Factor in Abiotic Stress Resistance and Growth

NAC proteins constitute one of the largest families of plant-specific transcription factors, and a number of these proteins participate in the regulation of plant development and responses to abiotic stress. T. HALOPHILA STRESS RELATED NAC1 (TsNAC1), cloned from the halophyte Thellungiella halophila, is a NAC transcription factor gene, and its overexpression can improve abiotic stress resistance, especially in salt stress tolerance, in both T. halophila and Arabidopsis (Arabidopsis thaliana) and retard the growth of these plants. In this study, the transcriptional activation activity of TsNAC1 and RD26 from Arabidopsis was compared with the target genes' promoter regions of TsNAC1 from T. halophila, and the results showed that the transcriptional activation activity of TsNAC1 was higher in tobacco (Nicotiana tabacum) and yeast. The target sequence of the promoter from the target genes also was identified, and TsNAC1 was shown to target the positive regulators of ion transportation, such as T. HALOPHILA H+- PPASE1, and the transcription factors MYB HYPOCOTYL ELONGATION-RELATED and HOMEOBOX12. In addition, TsNAC1 negatively regulates the expansion of cells, inhibits LIGHT-DEPENDENT SHORT HYPOCOTYLS1 and UDP-XYLOSYLTRANSFERASE2, and directly controls the expression of MULTICOPY SUPPRESSOR OF IRA14. Based on these results, we propose that TsNAC1 functions as an important upstream regulator of plant abiotic stress responses and vegetative growth.