Exiguobacterium aurantiacum SA100 induces antioxidant enzymes and salinity tolerance gene expression in wheat

This study evaluated the effects of Exiguobacterium aurantiacum SA100 on wheat (Triticum aestivum) growth under varying levels of salinity stress. Results indicated that SA100 significantly enhanced seed germination, root and shoot length, and fresh and dry biomass across salinity levels, particularly at 50 and 100 mM NaCl. Inoculation improved antioxidant enzyme activities (CAT, APX, POD, PPO), increased total phenolic content, and reduced oxidative damage by lowering MDA and H₂O₂ levels under 150 mM salinity. Ionic balance was maintained, with significant increases in K⁺, Mg⁺⁺, and Ca⁺⁺ and a reduction in Na⁺ accumulation. Gene expression analysis revealed upregulation of salt-tolerance genes (NAC7, NHX1, SOS1) and downregulation of stress-responsive genes (GS1, DREB2, DHN13, WRKY32). Principal component analysis confirmed that SA100 promotes salinity tolerance by modulating both biochemical and molecular responses. These findings suggest E. aurantiacum SA100 as a promising bioinoculant for enhancing wheat resilience under salinity stress.