Title SCREENING OF ANTIFUNGAL POTENTIAL OF OCHROBACTRUM CICERI AGAINST SCLEROTIUM ROLFSII

Abstract

The soil-borne fungus Sclerotium rolfsii Sacc., which causes collar rot, is a major constraint of chili
(Capsicum annum L.) production causing substantial yield loss in Pakistan. Bacterial biocontrol agents are among the
favored trends as efficient and eco-friendly agents to mitigate disease stress in modern agriculture. The present study
assess in vitro antifungal potential of Ochrobactrum ciceri against S. rolfsii through dual culture, modified dual
culture, and novel ring methods. Initially, the pathogenicity of the S. rolfsii was confirmed in the chili plants, later
antifungal potential of O. ciceri was determined. Results of pathogenicity assays revealed that S. rolfsii was a virulent
pathogen of chili, which produced transparent, thin-walled, and septate hyphae with clamp connections and abundant
sclerotia on malt extract agar medium plates. Antifungal assays indicated that O. ciceri hold considerable antimycotic
activity against S. rolfsii by inhibiting 98-100%, 69-70%, and 55-70% of the fungal growth by the novel ring, modified
dual culture, and dual culture methods, respectively. The novel ring method was found more effective for rapid
assessment of the bacterial antifungal activity as it caused 100% and 98% fungal growth inhibition after 7 and 15 days
of incubation, respectively as compared to the conventional dual culture plate assay. It was concluded that for the
screening of potential bacterial antagonists against phytopathogenic fungi, the novel ring methods could be utilized as
a rapid assessment of bacteria, which not only reduces required resources but is also found as an efficient method for
reliable results as compared to conventional dual culture plate assay.