Evaluation of the Plant Growth-Promoting Potential of Bacillus subtilis Isolated from the Rhizosphere of Berberis aristata for Improving Drought Stress Tolerance in Tomato (Solanum lycopersicum)
Abstract
The rhizosphere is a very favourable environment for the presence of a wide range of microorganisms, which allow many beneficial interactions between the plants and microorganisms. Bacillus species are known as plant growth promoting rhizobacteria (PGPR) to improve the growth and productivity of plants, among these microbes. All seven isolates were found to be Gram-positive bacteria and had multiple plant growth promoting abilities such as phosphate solubilization, zinc solubilization, production of indole-3-acetic acid (IAA), phytase, siderophores, hydrogen cyanide (HCN) and 1aminocyclopropane-1-carboxylate (ACC) deaminase. They further showed capability of biofilm formation and antagonism to other microorganisms. All isolates were identified as members of the Bacillus genus by molecular identification with 16S rRNA gene sequencing. All isolates were found to colonize tomato roots effectively under tissue culture and greenhouse conditions and colonization appeared to increase with time, over 15 days. In the greenhouse experiment, the effect of the isolates on plant growth was evaluated after 60 days of incubation, and isolate TRS-7 and TRS-8 exhibited the highest plant growth promoting potential, which makes them suitable as a bioinoculant to improve tomato production.