Unveiling broad-spectrum microbial antagonists for sustainable managementof seed-borne diseases of lentil (Lens culinaris)

Lentil (Lens culinaris Medik) productivity is significantly affected by seed-borne pathogens such as Fusarium oxysporum f.sp. lentis, Rhizoctonia solani, and Botrytis cinerea. The use of indigenous rhizospheric microbes as broad-spectrum biocontrol agents offers a sustainable strategy for disease management. The present investigation was conducted to isolate, characterise, and identify indigenous rhizospheric microorganisms possessing biocontrol and plant growth promoting (PGP) attributes. Forty fungal and thirty bacterial strains were isolated from lentil rhizosphere soil collected during winter (rabi) season of 2023–24 at ICAR-Indian Agricultural Research Institute, New Delhi, and screened for antagonist activity against the targeted pathogens employing a dual culture assay and biochemical traits. Among them, three fungal (F11, F16, F27) and two bacterial (B2, B13) isolates exhibited the strong and consistent inhibition of all pathogens. Morphological and cultural characterisation revealed typical features of potentialantagonists, which were validated by molecular identification. Internal transcribed spacer (ITS) region sequencing identified the fungal isolates as Trichoderma harzianum (F11), Trichoderma asperellum (F16), and Talaromyces flavus (F27), whereas the bacterial isolates were identified through 16S rDNA sequencing as Pseudomonas fluorescens (B2) and Bacillus subtilis (B13). Phylogenetic analysis validated their taxonomic affiliation. Furthermore, the isolates exhibited multiple biocontrol and PGP traits, including hydrolytic enzymes, siderophores, hydrogen cyanide (HCN), ammonia, phosphate solubilisation, and indole-3-acetic acid (IAA). The combined expression of antagonistic and PGP activities highlights the potential of these indigenous microbial isolates as promising candidates for the development of eco-friendly biocontrol formulations, providing a strong basis for further evaluation under greenhouse and field conditions for integrated management of lentil diseases.