Characterization and isolation of 1-aminocyclopropane1-carboxylate (ACC) deaminase-producing, plant growth-promoting rhizobacteria from the rhizosphere of Egyptian wheat cultivars for improved drought resilience.

Drought stress severely damages the growth and development of wheat and leads to lower crop production. The application of plant growth-promoting rhizobacteria (PGPR) is a sustainable approach that enhances plant tolerance to drought. This study investigated whether different bacterial isolates could promote wheat growth under drought conditions. A total of 73 bacterial isolates were obtained from the rhizosphere of Egyptian wheat cultivars, 30 of which exhibited ACC deaminase activity. The isolates were selected based on various PGPR characteristics, including phosphate solubilization, siderophore production, nitrogen fixation, indole-3-acetic acid production, biofilm formation, and antagonistic abilities. The active ACC colonies were screened for these traits and based on in vitro promotion of wheat plant growth, root inoculum from four wheat plants was used and grown under drought conditions. The percentage yield of wheat plants increased in the weight of wheat plants, while in total biomass it was found that the treatments showed significant differences compared to the control. The most effective ACC was from the wheat isolate B. subtilis. The bacterial types were identified at the genus level by sequencing the 16s rRNA gene. In conclusion, this research suggests PGPR such as V. paradoxus and K. oxytoca have the potential to reduce the effects of drought stress in Egyptian wheat cultivars.