EXPLOITATION OF PROMISING NATIVE STRAINS OF BACILLUS SUBTILIS WITH ANTAGONISTIC PROPERTIES AGAINST FUNGAL PATHOGENS AND THEIR PGPR CHARACTERISTIC

N. Singh, S. Raina, D. Singh, M. Ghosh, A.I.A.I. Helfish

Abstract


Fifteen Bacillus subtilis strains which produced antifungal substances against plant pathogens i.e. Fusarium oxysporum f. sp. melonis, Rhizoctonia solani (RRS1) and Rhizoctonia solani (PRS1) were characterized biochemically and screened in vitro for their plant growth promoting traits as indole acetic acid (IAA), siderophore and hydrogen cyanide (HCN) production, as well as their antagonistic activity. In dual culture assays B. subtilis strains implicated decreased growth of F. oxysporum f. sp. melonis (upto 85.5%) causing muskmelon wilt, R. solani (RRS1) (upto 73.7%) causing sheath blight of rice and R. solani (PRS1) (upto 82.5%) causing black scurf of potato. The production of indole acetic acid (IAA) by all rhizobacteria was investigated as important mechanism for plant growth stimulation. Maximum in vitro IAA values were producedby B. subtilis FDK-21L (7.0 µg/ml) by addition of Ltryptophan in the culture medium. B. subtilis FDK-21L presented high activity of siderophore production. Diameter of halo varied from 0.4 to 3.2 cm on CAS agar plates. FDK-21L showed significant reduction of muskmelon wilt incidence (65.7%), disease severity of sheath blight of rice (70.8%) and black scurf of potato (97.2%). As B. subtilis FDK-21L exhibited several traits beneficial to the host and showed promising results when applied as bioinoculant, it may be used to develop new, safer and effective formulation as an alternative to chemical fungicides.

Keywords


Fusarium oxysporum; indole acetic acid; Rhizoctonia solani; siderophore

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DOI: http://dx.doi.org/10.4454/jpp.v99i1.3809

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EDIZIONI ETS, Pisa, Italy