Fluorescent Pseudomonas Mediated Alleviation of Trivalent Chromium Toxicity in Ragi Through Enhanced Antioxidant Activities

Heavy metal pollution due to incessant industrialization is a major concern as it affects the growth and productivity of many plants through structural damage, growth inhibition and decline in physiological functions. In the present study, ragi, a crop with strong sustainability against environmental variations, has been used as an experimental plant in alleviating chromium stress using isolates of fluorescent Pseudomonas (FP). Forty-two FP isolates from rhizosphere soils, both from polluted and non-polluted sites of Karnataka, were morphologically and biochemically characterized and screened for plant growth promoting (PGP) traits viz., Indole-like compounds, siderophore, phosphate solubilization, ammonia and vigour index. Best thirteen isolates based on PGP traits were shortlisted for further studies out of which ragi plants were treated with three isolates (JUP2, JUP5, and JUP9) under chromium stress under green house studies based on their growth promoting traits. The plant leaf samples were analyzed biochemically for total proteins, phenolic content and enzymatic and non-enzymatic antioxidants. The results showed that the priming with three Pseudomonas isolates contributed in positive physiological variation, pertaining to chromium induced oxidative stress, in host plant. Additionally, significant growth inhibition by heavy metal toxicity was also alleviated by Pseudomonas priming.