Assessment of antibiosis potential of Bacillus sp. against the soil-borne fungal pathogen Sclerotium rolfsii Sacc. (Athelia rolfsii (Curzi) Tu & Kimbrough)

Abstract

Background This study aimed to investigate the rhizosphere bacterial isolates’ antagonistic property against the soil-borne fungal phytopathogen, Sclerotium rolfsii Sacc. (Athelia rolfsii (Curzi) Tu & Kimbrough). The chemical control of the disease caused by S. rolfsii is economically and environmentally unsustainable, and therefore, a bio-control agent in the form of rhizospheric bacteria is gaining importance. Main body Five rhizospheric Bacillus species viz. B. subtilis subsp. Subtilis str.168 (accession no. MH283878), B. siamensis strain PDA 10 (accession no. MH283879), B. amyloliquefaciens strain 1034 (accession no. MH283880), B. velezensis strain FZB42165 (accession no. MH283881), and B. atrophaeus strain NBRC 15539 (accession no. MH283882) were assessed for their antagonistic potential against S. rolfsii based on 3 different screening methods. Among these, 100% fungal growth inhibition by all 5 Bacillus spp. was observed in the novel ring method, whereas in the dual culture method, the maximum growth inhibition was (58%) exhibited by the strain NBRC 15539 of B. atrophaeus. The antagonistic activity showed by the modified dual culture method was also relatively high, and the highest activity (93.7%) was shown by the strain NBRC 15539 of B. atrophaeus. Besides, the Bacillus sp. was also evaluated for their plant growth-promoting attributes and other properties such as the production of siderophore, HCN, amylase, protease, lipase, and ammonia, including their assessment for chitinase and cellulase activity. Conclusion The study provided empirical evidence of Bacillus sp. antagonistic potential against S. rolfsii and should be of contributive value in developing a biocontrol agent for this highly important crop fungal pathogen.

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“…These results suggest that the antifungal compounds produced by the bacteria were responsible for the suppression of plant pathogen and the disease. Antibiosis by bacterial antagonists is implicated as a typical mechanism in their biocontrol activity against S. rolfsii [51]. Additionally, other data of this study demonstrated that the tested rhizobacteria inhibited oxalic acid production of S. rolfsii and showed abilities to use oxalic acid as a growth substrate.…”

Rhizospheric bacteria as potential biocontrol agents against Fusarium wilt and crown and root rot diseases in tomato

“…Previous reports have also identified siderophore production as a biocontrol mechanism against fungal pathogens in other plant species ( El-Sayed et al, 2014 , Vinayarani and Prakash, 2018 ). Bacillus subtilis , B. siamensis and B. amyloliquefaciens are able to produce siderophores, which may help to decrease Fusarium wilt caused by Fol as reported with other isolates of the B. subtilis group ( Kumari et al, 2021 ). The bacteria in this study did not show any chitin degradation properties.…”

An Assessment of Two Application Methods Involving the Use of Bacillus spp. Against Sclerotium rolfsii for Plant Growth-Promotion and Disease Management of Chickpea

“…Bacillus spp. also use some other mechanism like antibiosis and competition to colonize with S. rolfsiis sclerotia and mycelium (Gholami et al, 2014;Kumari et al, 2021). Hence, the disease severity was lower in the bacteria treated chickpea plants as compared to the non-treated plants.…”