Inoculating maize (Zea mays L.) seeds with halotolerant rhizobacteria from wild halophytes improves physiological and biochemical responses of seedlings to salt stress

Salinity stress is a major environmental factor that poses a significant constraint to plant growth, threatening agricultural productivity and sustainability. This study investigated the potential of halotolerant bacteria, isolated from the rhizosphere of wild halotolerant plants in Turkey’s Salt Lake basin, to enhance salt stress tolerance in maize (Zea mays L.). The rhizospheres of 17 different wild halotolerant plants were selected for bacterial isolation, resulting in the identification of 22 halotolerant bacteria using 16S rRNA sequence analysis. Among these, 19 isolates were found to possess positive activity for 1-aminocyclopropane-1-carboxylate (ACC) deaminase and nitrogen fixation. When the maize seeds inoculated with these 19 isolates were grown under normal conditions, four isolates‒TG-4 (Halomonas arcis), TG-8 (Marinococcus tarigensis), TG-12 (Halobacillus dabanensis), and TG-20 (Halomonas eurihalina)–significantly stimulated seedling growth and development. To evaluate the effect of these four isolates on salt tolerance, inoculated seeds were grown under various salt conditions (0.0, 75, 150, and 250 mM NaCl). The responses of plants to salt stress were analyzed by evaluating growth parameters, membrane damage, photosynthetic pigment and proline content, reactive oxygen species and lipid peroxidation levels, and antioxidant enzyme activities. According to the parameters, the results indicated that TG-4, TG-8, and TG-12, in particular, have the potential to function as plant growth-promoting rhizobacteria and effectively enhance salt stress tolerance in the maize seedlings. Overall, this research highlights the potential of halotolerant bacteria to improve salt stress tolerance in maize plants through multifaceted mechanisms, offering valuable insights for sustainable agriculture in saline environments.