Prevention of collar rot disease in germinating peanut seedlings by Azotobacter sp. RA2

Abstract

Use of plant growth promoting rhizobacteria (PGPR) to increase the production and decrease disease occurrence is a useful, ecofriendly method in agriculture. A rhizospheric bacterial culture named RA2 was isolated from peanut rhizosphere from Junagadh region of Gujarat, India and showed different direct and indirect plant growth promoting activity like indole acetic acid, gibberellic acid, siderophore, hydrogen cyanide, Ammonia and (1‐Aminocyclopropane‐1‐Carboxylate) deaminase production, N2 fixation, phosphate and potassium solubilization in vitro. RA2 was able to protect peanut germinating seedling from A. niger infection and reduce collar rot disease incidence from 72–60% to 41–35% and increase germination percentage from 75–70% to 97–82% in two varieties GG20 and GG2 of peanut. RA2 was found to induce resistance in A. hypogaea L. seedlings via induction of different defense related enzyme like phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, lipoxygenase and pathogenesis related protein like chitinase and β– 1, 3‐ glucanase. Jasmonic acid, one of the major signaling molecules during induce systemic resistance, was also found to induce due to RA2 treatments. RA2 bacterium also promoted peanut growth and reduced A. niger infection in pot studies. 16S rDNA sequence of RA2 showed 99 % homology to Azotobacter species.Support or Funding InformationAuthors are thankful to BRD School of Biosciences, Sardar Patel University for providing infrastructure and all necessary facilities. Authors are also grateful to University Grant commission (UGC Major Research Project F.No. 39‐247/ 2012 (SR)) for providing financial aid.