Assessing the prospects of Streptomyces sp. RP1A-12 in managing groundnut stem rot disease caused by Sclerotium rolfsii Sacc uri icon

abstract

  • Stem rot of groundnut caused by the soilbornepathogen Sclerotium rolfsii can cause significant yieldlosses. Biological control of stem rot using actinomycetesis a viable alternative to existing fungicidal management.Though actinomycetes are prolific antibiotic producers,reports pertaining to their use in groundnut disease management are limited. Here, actinomycetes were isolatedfrom groundnut rhizospheric soils and screened for antagonism against S. rolfsii through a dual culture assay. Culture filtrates and crude extracts of the potential candidates were screened further for extracellular antifungal activityand characterized for biocontrol and plant-growth-promotingtraits. A promising candidate was tested undergreenhouse conditions as whole organism as well as crudeextracts. Isolate RP1A-12 exhibited high antagonismagainst S. rolfsii in dual culture assay (69 % inhibition),culture filtrate assay (78?100 % inhibition at various concentrations)and crude extract assay (100 % inhibition with1 % crude extracts). Moreover, germination of sclerotia ofthe test pathogen was inhibited with 1 % crude extracts.Strain RP1A-12 produced hydrogen cyanide, lipase, siderophoresand indole acetic acid. Oxalic acid production byS. rolfsii was also inhibited by crude extracts of RP1A-12.In greenhouse studies, RP1A-12 reduced stem rot severity.Overall, our results suggest that isolate RP1A-12 has potential biocontrol capabilities against stem rot pathogen.Molecular characterization based on 16S rRNA genesequencing of RP1A-12 identified it as a species ofStreptomyces, closely related to S. flocculus

publication date

  • 2016
  • 2016