Efficacy of Streptomyces Formulation for the Induction of Defense Response in Rice Challenged with Bacterial Leaf Blight Pathogen Xanthomonas oryzae pv. oryzae
2025
N. Jaivel | C. Partheeban | S. Kasinathan | R. Rajesh
The present study was conducted during the kharif season (June–September, 2019) at the Department of Agricultural Microbiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India (11.01°N, 76.93°E) to evaluate the efficacy of a Streptomyces-based formulation in managing bacterial leaf blight (BLB) of rice. Biological control has been gaining increasing importance in recent years for the management of plant diseases. A water-soluble starch-based formulation was developed using dried spores and mycelia of Streptomyces sp. TC1, a strain exhibiting inhibitory activity against Xanthomonas oryzae pv. oryzae, the causal organism of BLB. The TC1 formulation effectively reduced seed-borne infection and enhanced the germination percentage of paddy seeds by 78.7%. Foliar application of the formulation at varying concentrations significantly induced systemic resistance in rice plants, as evidenced by increased activity of defense-related enzymes such as peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), superoxide dismutase (SOD), and elevated total phenol content. Among the tested concentrations, the 0.4% TC1 formulation was identified as optimal, resulting in a 56.6% reduction in disease incidence under pot culture conditions compared to the untreated control. Furthermore, application of the TC1 formulation up to 1% concentration did not exhibit any phytotoxic effects on rice plants. The findings suggest that the TC1 formulation could serve as a promising biocontrol agent for the eco-friendly and sustainable management of bacterial leaf blight in rice cultivation.
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