Isolation and Characterization of Antagonistic Actinomycetes from Natural Sources for the Biological Control of Oily Spot Disease in Pomegranate

Abstract

Oily spot disease, caused by the fungal pathogen Colletotrichum spp., poses a significant threat to pomegranate cultivation worldwide, leading to substantial yield losses. In this study, we isolated and characterized antagonistic actinomycetes from various natural sources to assess their potential for biological control against oily spot disease in pomegranate. Actinomycetes were isolated from soil, rhizosphere, and plant debris using standard techniques. Screening assays, including dual culture and metabolite-based assays, were employed to identify isolates exhibiting antagonistic activity against Colletotrichum spp. Selected antagonistic isolates were characterized morphologically, physiologically, and biochemically using microscopy, biochemical tests, PCR, and sequencing. Isolation efforts yielded a diverse collection of actinomycetes, among which a percentage exhibited antagonistic activity against Colletotrichum spp. Characterization of selected antagonistic isolates revealed distinct morphological features, physiological traits, and biochemical profiles. Our results suggest the potential of these antagonistic actinomycetes as biocontrol agents against oily spot disease in pomegranate. Discussion on the mode of action of these isolates highlights potential mechanisms such as competition for nutrients, production of antimicrobial metabolites, and induction of systemic resistance in pomegranate plants. Practical implications include the development of sustainable management strategies for oily spot disease and the promotion of eco-friendly agricultural practices. Future research directions could focus on optimizing the application of antagonistic actinomycetes in commercial formulations and exploring their interactions with pomegranate cultivars to enhance efficacy. This study contributes to the exploration of natural sources for biocontrol agents and offers insights into the potential application of antagonistic actinomycetes for managing oily spot disease in pomegranate, thereby addressing the need for sustainable solutions in agriculture.