Abstract
BACKGROUND: Early blight (EB), caused by Alternaria solani, is one of the alarming diseases that restrict tomato production globally. Existing cultural practices and fungicide applications are not enough to control early blight diseases. Therefore, the study aimed to isolate, identify, and characterize an endophytic Streptomyces exhibiting the potential to control early blight in tomato and also promote plant growth. RESULTS: From a Citrus jambhiri leaf, an endophytic Streptomyces sp. with antagonistic activity against Alternaria solani, Colletotrichum acutatum, Cladosporium herbarum, Alternaria brassicicola, Alternaria sp., Fusarium oxysporum and Fusarium sp. was isolated. It was identified as a Streptomyces sp. through 16S ribosomal DNA sequence analysis and designated as SP5. It also produced indole acetic acid which was confirmed by Salkowski reagent assay, TLC and HPLC analysis. Treatment of pathogen infected plants with Streptomyces sp. SP5 antagonists (culture cells/culture supernatant/solvent extract/ acetone precipitates) decreased the early blight disease incidence and significantly increased the various agronomic traits. CONCLUSION: The present study concluded that Streptomyces sp. SP5 possessed antifungal activity against different fungal phytopathogens and had significant potential to control early blight disease and promote plant growth.