Efficiency of silicate solubilizing Bacillus tequilensis SKSSB09 in enhancing drought mitigation in Zea mays L.

Abstract

Drought is an abiotic stress which causes huge economic losses in agriculture. Silicon is considered the best element which plays a key role in inducing drought mitigation properties. Silicate solubilizing bacterial strains were evaluated for their survivability in the low water activity potential. Bacillus tequilensis SKSSB09 showed high survivability at 40% polyethylene glycol 6000 concentration i.e. -1.76 MPa. ACC deaminase activity of the silicate solubilizing bacterial strains was assessed, among which B. tequilensis SKSSB09 showed ACC deaminase production in Dworkin and Foster minimal media. In–planta studies showed the survivability of maize plants till 23 days without water. Silicon deposition in the maize leaves showed 0.0384±0.0021μg/g. The leaf membrane stability index of the inoculated plants showed 72.2 ±3.8% which also correlates with the epicuticular wax content (2.4±0.56 mg/g). Proline content plays a key role in enhancing drought tolerance in plants. The inoculated plants showed high proline content (39.8±3.7 μg/g) which plays a key role in maintaining the cell sap and increasing the photosynthetic rate. Scanning electron microscopic studies revealed the deposition of silicon in the leaves and the formation of sunken stomata which reduces the transpiration rate. Based on the above results, Bacillus tequilensis SKSSB09 can be used as a plant growth-promoting rhizobacterial inoculant during drought conditions.