PJB-2021-447
Seed inoculation of halotolerant rhizobacteria isolated from wild halophytic plants ameliorates salt stress response in maize (Zea mays L.)
Ökkeş ATICI
Abstract
This study investigates the potential of halotolerant bacteria isolated from the rhizosphere of wild halotolerant plants in the Salt Lake (Turkey) basin to improve salt stress tolerance in maize (Zea mays L.). Twenty-two halotolerant bacteria were isolated from the root rhizosphere of 17 wild halotolerant plants and isolates were identified according to 16S rRNA sequence analysis. Nineteen of the isolates exhibited positive activity for ACC (1-aminocyclopropane-1-carboxylate) deaminase and nitrogen fixation. Based on preliminary tests, of isolates, Halomonas arcis (TG-4), Marinococcus tarijensis (TG-8), Halobacillus dabanensis (TG-12), and Halomonas eurihalina (TG-20) were inoculated into maize seeds (108 CFU/mL), and then inoculated and uninoculated seeds were grown in pots containing different salt conditions (0, 75, 150, 250 mM NaCl) for 15 days at 22/25oC (16/8 h daylength). Salt applications alone decreased the growth and biomass of maize seedlings while increasing membrane damage. However, the inoculation of these 4 isolates mitigated the negativities caused by the salt applications. Of the isolates, TG-12 reduced proline content in seedlings, which increased by the salt applications. The salt applications caused high Na+ accumulation in both root and shoot but diminished K+ content in the shoot while enhanced in the root. The bacterial inoculations, on the other hand, generally reduced Na+ levels in both organs of seedlings and ameliorated the K+/Na+ ratio, and the isolates TG-8 and TG-12 were more successful in mitigating the salt symptoms. The results show that TG-8 and TG-12 isolates have plant growth-promoting rhizobacteria (PGPR) potential and may ameliorate the salt tolerance of maize.
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