The Wheat Nucleoredoxin TaNRX1-2D Gene Ameliorates Salt Tolerance in Wheat (Triticum aestivum L.)

Wheat is one of the most important crops contributing to global food and nutritional security. However, the gradual increase in soil salt content significantly impairs wheat growth and development, ultimately resulting in reduced yields. Therefore, enhancing the salt tolerance of wheat is of significant importance. Salt stress commonly induces oxidative stress in plants, and nucleoredoxin (NRX) has been shown to effectively maintain redox homeostasis under stress conditions. However, the functional role and molecular mechanism of the <i>NRX</i> gene in regulating salt tolerance in wheat remain to be elucidated. The results of this study demonstrated that <i>TaNRX1-2D</i> homologous overexpression (OE) lines exhibited significantly enhanced tolerance to salt stress. The survival rate and antioxidant enzyme activities (including superoxide dismutase and catalase) in the OE lines were higher than those in the wild type (WT). In contrast, the levels of superoxide anion (O₂^-), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) in the OE lines were markedly lower than those in the WT. Conversely, the RNA interference (RNAi) lines displayed opposing trends. The results of yeast one-hybrid (Y1H) and dual luciferase assays (D-LUC) demonstrated that the TaERD15L-3B transcription factor positively regulated the expression of the <i>TaNRX1-2D</i> gene by binding to the ABRERATCAL <i>cis</i>-acting element in the <i>TaNRX1-2D</i> promoter. Through luciferase complementation assay (LCA), bimolecular fluorescence complementation (BiFC) assay, and a "mutation capture strategy", it was found that TaNRX1-2D (C54, 327S) interacted with TaCAT2-B, indicating that TaCAT2-B was the target protein of TaNRX1-2D. The results of data-independent acquisition (DIA) proteomics analysis indicated that TaNRX1-2D may mediate salt tolerance in wheat through the positive regulation of nsLTP protein abundance and the negative regulation of hexokinase protein abundance. In general, the TaERD15L-3B/TaNRX1-2D regulatory module played a crucial role in conferring salt tolerance in wheat. This study provided an important theoretical basis and identified a potential gene target for developing salt-tolerant wheat varieties through molecular breeding approaches.