Analysis of Antagonistic Potential of Secondary Metabolites and Organic Fractions of Trichoderma Species against Alternaria Alternata.

Role of Trichoderma species is well documented as antagonists as well as plant growth enhancers. Presently, the fungicidal potential of three Trichoderma species namely, T. koningii (FCBP769) , T. viride (FCBP904) , and T. harzianum (FCBP1277) was assessed against Alternaria alternata that causes leaf necrotic spots of Syzygium cumini and broad range of other plants using 0, 15, 30, 45, 60 and 75% dilutions of filtrates. There was a significant reduction of around 40-95%, 22-86% and 52-91% in fungal biomass by T. koningii, T. viride and T. harzianum, respectively. In fractionation bioassays, Trichoderma metabolites were partitioned using organic solvents viz., n-butanol, n-hexane, chloroform and ethyl acetate. Antifungal activity at different concentrations (10, 20, 30, 40 and 50 ppm) was assessed against the pathogen. Ethyl acetate fraction of T. koningii extract displayed the most promising activity resulting in 10-90% suppression in biomass. In case of T. viride butanol fraction proved the most effective in retarding the growth of pathogen from 20 to 80%. While T. harzianum extract revealed 55-85% arrest in fungal biomass due to n-hexane fraction. Present study concludes that test Trichoderma species demonstrated a strong fungicidal activity against A. alternata. Current research offers the possibility of developing strategies for controlling pathogens with bioactive metabolites of Trichoderma.