Halotolerant Staphylococcus epidermidis DS2 enhances growth, stress resilience, and ion homeostasis in wheat under saline conditions.

Plant growth-promoting rhizobacteria (PGPR) are essential for increasing crop resistance to abiotic stressors, especially salinity. The halotolerant rhizospheric strain Staphylococcus epidermidis DS2, isolated from cotton rhizosphere, was tested for its ability to promote salt tolerance in two wheat cultivars (Wadan and Pirsabak2019). The strain exhibited a variety of plant growth promoting (PGP) properties in saline conditions, such as exopolysaccharides (3.33 mg mL⁻1), indole-3-acetic acid (128 µM mL⁻1), and ACC deaminase activity (1.92 µM mg⁻1 protein h⁻1). In both cultivars, DS2 inoculation markedly increased fresh and dry biomass, as well as shoot and root length, in non-saline circumstances. Under moderate salt stress (100 mM NaCl), DS2-treated plants exhibited elevated levels of chlorophyll a and total chlorophyll (up to 37% in Wadan), as well as improved relative water content. In conditions of significant stress (150 mM NaCl), inoculated plants preserved elevated chlorophyll concentrations and exhibited diminished oxidative damage, as seen by reduced levels of malondialdehyde (48%) and hydrogen peroxide (23%). Activities of antioxidant enzymes, such as peroxidase (168%) and catalase (45%), were increased. The DS2 inoculation diminished Na⁺ buildup while enhancing the absorption of K⁺, Mg2⁺, and Ca2⁺, hence facilitating improved ionic equilibrium and stress alleviation. The results indicate that S. epidermidis DS2 has potential as a bioinoculant to improve wheat performance in saline environments.