Glyphosate induced toxicity to chickpea plants and stress alleviation by herbicide tolerant phosphate solubilizing Burkholderia cepacia PSBB1 carrying multifarious plant growth promoting activities

Abstract

In this study, strain PSBB1 isolated from Vicia faba rhizosphere was identified as Burkholderia cepacia, by 16S rDNA sequence analysis and characterized. Strain PSBB1 tolerated glyphosate up to 3200 μg ml⁻¹ and produced IAA (81.6 μg ml⁻¹), ACC deaminase (69.3 mg⁻¹ protein h⁻¹), SA (39.3 μg ml⁻¹) and 2,3-DHBA (26.6 μg ml⁻¹), solubilized insoluble P (50.8 μg ml⁻¹) and secreted 29.4 μg ml⁻¹ exopolysaccharides, which decreased with increasing concentrations of glyphosate. Cell damage following glyphosate application was visible under SEM and CLSM. The phytotoxicity of glyphosate on chickpea was variable but significant. B. cepacia mitigated toxicity and enhanced the size, dry matter, symbiosis, seed attributes and nutritional contents of chickpea. Further, B. cepacia strain PSBB1 declined the levels of CAT, POD, APX and GPX and MDA contents at 4332 μg kg⁻¹ soil glyphosate. Proline also increased under glyphosate stress but declined in B. cepacia inoculated plants. The ability to tolerate higher concentration of glyphosate, the capacity to secrete plant growth regulators even under herbicide stress and potential to reduce the level of proline and antioxidant enzymes makes B. cepacia as an interesting choice for enhancing chickpea production in soils contaminated even with herbicides.