Variovorax soli mediated growth amelioration and abiotic stress alleviation in Capsicum annuum

In present study, rhizobacterial strains were isolated from soil sample and screened for plant growth promoting and antagonistic potential in vitro condition. The isolate exhibiting maximum plant growth promoting and antagonistic potential was subjected to biochemical characterization and 16S rDNA gene sequencing. Based on molecular characterization, the isolate was identified as Variovorax soli with NCBI accession number LC372534. The PGP potential of Variovorax soli was established as it augmented plant growth in control and under salt, drought, heavy metal stress conditions. Positive results for in-vitro tests viz. amylase, hydrogen cyanide, lipase, catalase, protease and chitinase production confirmed the antagonistic efficacy of Variovorax soli. Nutrient acquisition enhancing efficiency of V. soli was established as positive results were recorded for PGP tests viz. siderophore production, nitrogen fixation, phosphate solubilization and exopolysaccharide production. Plants inoculated with V. soli induced phytohormonal modulation (viz. increase in IAA level and reduction in stress ethylene level) for enhanced shoot, root length, increased plant fresh and dry weight, chlorophyll and proline content for extensive root system, plant growth and alleviation of salt, drought, arsenic stress impact as compared to uninoculated plants, thus confirming its ability as biological fertilizers. Along with (IAA) indole 3-acetic acid and (ACC deaminase) 1-aminocyclopropane 1-carboxylic acid deaminase, certain other extracellular exudates of PGPR serve as signaling molecules to trigger abiotic stress responsive pathway. V. soli is therefore a promising green alternative to chemical fertilizers to induce abiotic stress tolerance and reclaim soil fertility to elevate agricultural productivity.