Isoflavone content and antioxidant activity of soybean inoculated with plant-growth promoting rhizobacteria

Abstract

Plant-growth promoting rhizobacteria (PGPR) elicit activation of the phenylpropanoid pathway in plants, which leads to phenolics production and enhanced antioxidant capacity. The purpose of this work was to assess the antioxidant activity of soybean plants, Glycine max L., inoculated with PGPR (isolates of Azotobacter chroococcum, Streptomyces sp. and mixture of these) during plant development, as well as the yield of inoculated soybean plants. PGPR applied in the experiment stimulated flavonoids and isoflavone synthesis, which enhanced the non-enzymatic antioxidant ability of the soybean plants. Moreover, PGPRs stimulated the accumulation of daidzein and genistin in soybean seedlings (5-fold and 2-fold compared to the control values, respectively). The mixture of PGPRs had a positive impact on the antioxidant activity (10-20 % higher activity) and yield components of soybean, which proposed this inoculum as possibly a potent bio-fertilizer in soybean production.