Bacillus strains enhance wheat growth and resilience to drought and Fusarium stress

Drought stress and Fusarium diseases are major yield-limiting factors in wheat, and their management with chemical pesticides poses environmental and resistance risks. Plant growth-promoting Bacillus strains offer a sustainable alternative due to their stress tolerance, antifungal activity, and growth-promoting traits. This study evaluated three Bacillus strains (TII-19, TCG-6, and TMG-6) and a consortium (TCG-6 + TMG-6) for their ability to promote wheat growth, enhance drought tolerance, and reduce Fusarium infection. All strains grew under 20 % PEG-6000 and exhibited enhanced biofilm production. In planta, Bacillus strains, particularly TMG-6 and the consortium, improved shoot length, root growth, biomass, and leaf number under both irrigated and drought conditions. The consortium further enhanced photosynthetic pigments, proline, protein, and phenol content, maintained higher relative water content, and reduced oxidative damage by increasing antioxidant enzyme activity under drought stress. Both Bacillus treatments and their cell-free supernatants reduced Fusarium severity in spikelets and leaves by over 50 %, with TMG-6 showing the strongest effect. Detached leaf assay confirmed that bacterial treatments reduced Fusarium lesions and induced hyphal alterations. Overall, Bacillus strains, especially the TCG-6 + TMG-6 consortium, effectively promote wheat growth, enhance resilience to drought, and reduce Fusarium lesions on wheat leaves, highlighting their potential as eco-friendly biocontrol agents.