Assessing the prospects of Streptomyces sp. RP1A-12 in managing groundnut stem rot disease caused by Sclerotium rolfsii Sacc
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Simi Jacob, Ramgopal Rao Sajjalaguddam, K. Vijay Krishna Kumar, Rajeev Varshney, Hari kishan Sudini. (31/3/2016). Assessing the prospects of Streptomyces sp. RP1A-12 in managing groundnut stem rot disease caused by Sclerotium rolfsii Sacc. Journal of General Plant Pathology, 82 (2), pp. 96-104.
Abstract
Stem rot of groundnut caused by the soilborne
pathogen Sclerotium rolfsii can cause significant yield
losses. Biological control of stem rot using actinomycetes
is 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 isolated
from 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 activity
and characterized for biocontrol and plant-growth-promoting
traits. A promising candidate was tested under
greenhouse conditions as whole organism as well as crude
extracts. Isolate RP1A-12 exhibited high antagonism
against S. rolfsii in dual culture assay (69 % inhibition),
culture filtrate assay (78–100 % inhibition at various concentrations)
and crude extract assay (100 % inhibition with
1 % crude extracts). Moreover, germination of sclerotia of
the test pathogen was inhibited with 1 % crude extracts.
Strain RP1A-12 produced hydrogen cyanide, lipase, siderophores
and indole acetic acid. Oxalic acid production by
S. 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 gene
sequencing of RP1A-12 identified it as a species of
Streptomyces, closely related to S. flocculus
