TaPHL7–TaSOD7-4A regulatory pair enhances drought tolerance in wheat (Triticum aestivum L.)

• 20 SOD genes were identified in wheat and divided into three subfamilies. • TaSOD7 - 4A enhances drought tolerance of transgenic wheat. • TaPHL7 directly binds to the TaSOD7 - 4A promoter and activates its expression. • Overexpression and RNA interference of TaPHL7 enhance and reduce drought tolerance, respectively. • TaPHL7 – TaSOD7 - 4A regulatory pair broadens the mechanistic framework of drought stress responses. Drought stress severely constrains wheat production and presents a significant threat to global food security. Although superoxide dismutase (SOD) proteins are known to enhance drought resistance, the upstream regulatory mechanisms governing their expression remain poorly understood. In this study, a genome-wide analysis was conducted that identified 20 SOD genes in wheat. TaSOD7 - 4A overexpression in wheat significantly increased antioxidant enzyme activity and improved drought tolerance in transgenic lines. TaPHL7 was identified as an upstream transcriptional regulator of TaSOD7 - 4A using a combination of bioinformatic analyses and electrophoretic mobility shift, yeast one-hybrid, and dual-luciferase assays. Subcellular localization experiments confirmed that TaPHL7 protein is localized to the nucleus, and yeast two-hybrid assays demonstrated its transcriptional activation activity, which was mapped to the C-terminal region. Under drought stress, TaPHL7 overexpression significantly improved drought tolerance in transgenic wheat, accompanied by lower H 2 O 2 and malondialdehyde (MDA) contents, higher relative water content (RWC) and proline accumulation, and enhanced antioxidant enzyme activity. Conversely, TaPHL7 RNA interference wheat lines exhibited increased MDA content, decreased proline levels, and reduced antioxidant enzyme activity. Collectively, our experiments revealed the TaPHL7–TaSOD7-4A regulatory module as a key mechanism underlying positive drought responses and identified candidate genes with the potential to breed superior drought-resistant wheat lines.