TaNAC48 positively regulates drought tolerance and ABA responses in wheat (Triticum aestivum L.)

NAC family transcription factors (TFs) are important regulators in plant development and stress responses. However, the biological functions of NAC TFs in wheat are rarely studied. In this study, 43 putative drought-induced NAC genes were identified from de novo transcriptome sequencing data of wheat following drought treatment. Twelve wheat NACs along with ten known stress-related NACs from Arabidopsis and rice were clustered into Group II based on a phylogenetic analysis. TaNAC48, which showed a higher and constitutive expression level in Group II, was selected for further investigation. TaNAC48 transcript was up-regulated by drought, PEG, H₂O₂ and abscisic acid (ABA) treatment and encoded a nuclear localized protein. Overexpression of TaNAC48 significantly promoted drought tolerance with increased proline content, and decreased rates of water loss, malondialdehyde (MDA), H₂O₂ and O₂⁻ content. Root length and a stomatal aperture assay confirmed that TaNAC48-overexpression plants increased sensitivity to ABA. Electrophoretic mobility shift assay (EMSA) and luciferase reporter analysis indicated that TaAREB3 could bind to a cis-acting ABA-responsive element (ABRE) on TaNAC48 promoter and activate the expression of TaNAC48. These results suggest that TaNAC48 is essential in mediating crosstalk between the ABA signaling pathway and drought stress responses in wheat.