Bacillus methylotrophicus CSY-F1 alleviates drought stress in cucumber (Cucumis sativus) grown in soil with high ferulic acid levels

Abstract

Drought and ferulic acid (FA) inhibit plant growth. Here, we investigated whether Bacillus methylotrophicus CSY-F1 alleviates drought stress in cucumber (Cucumis sativus) plants grown in high-FA soil. Cucumber seedlings grown in high-FA soil were inoculated with CSY-F1 for 20 d, and then subjected to drought for 3 d. In rhizospheric soil of drought-stressed seedlings, CSY-F1 decreased FA levels and increased soil water contents, polysaccharide levels, and catalase, phosphatase, urease, and sucrase activities at low or high FA concentrations. In drought-stressed seedlings grown in FA-containing soil, CSY-F1 improved plant growth, and reduced leaf wilting; CSY-F1 decreased superoxide radical, hydrogen peroxide, and malonaldehyde levels. CSY-F1 increased superoxide dismutase (SOD), catalase, guaiacol peroxidase, ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione reductase activities in these seedlings. In addition, CSY-F1 elevated plant relative water content and osmotic potential, and enhanced ascorbate and glutathione contents, proline and soluble sugar levels, and catalase, copper/zinc SOD, manganese SOD, CsPYL1, and CsPYL2 transcript levels. CSY-F1 increases the polysaccharide levels and enzyme activities in soil, and enhances antioxidant enzyme activities, proline and soluble sugar levels, and transcript levels of CsPYL1 and CsPYL2 in leaves, thus alleviating drought stress in cucumber under FA conditions.