A NAC transcription factor, TaNAC5D-2, acts as a positive regulator of drought tolerance through regulating water loss in wheat (Triticum aestivum L.)

NAC transcription factors play critical roles in regulating drought stress. However, the drought-responsive NAC transcription factors are largely unexplored in wheat. In this study, we isolated a NAC gene, TaNAC5D-2, and characterized the function of TaNAC5D-2 as a positive regulator of drought tolerance. The expression level of TaNAC5D-2 was induced under drought or abscisic acid treatment. Transient expression and transcriptional activity assays showed that TaNAC5D-2 is localized to the nucleus, and the C-terminal region exhibited transcriptional activity. Overexpression of TaNAC5D-2 in Arabidopsis thaliana led to greater drought tolerance, fresh weight and dry weight than wild-type plants, and the water loss was significant inhibited in the leaves of overexpression lines. Conversely, silencing of TaNAC5D-2 in wheat seedlings led to increased water loss and decreased growth compared to control and negative control plants under drought stress. RNA-Seq and RT-qPCR revealed that many Group A PP2C genes were upregulated in the TaNAC5D-2 silenced plants compared to negative control. And silencing TaNAC5D-2 negatively regulate ABA-induced stomatal closure that led to higher water loss. These data suggest that TaNAC5D-2 acts as a drought-responsive regulator, possibly by an abscisic acid-mediated stomatal closure to control water loss under drought condition.