Morpho-molecular characterization, diversity analysis and antagonistic activity of Trichoderma isolates against predominant soil born pathogens

摘要

Trichoderma is an important antagonist fungi used in biological plant disease management. The present study was carried out to identify the antagonistic efficiency of native Trichoderma isolates against soil born pathogens and to characterize them based on morphological and molecular markers. Twenty-nine Trichoderma cultures were isolated from the agri-horticulture and forest tree rhizosphere. These isolates were identified as T. asperellum, T. aureoviride and T. virens based on the ITS sequences . The isolates produced dark green with or without border (n = 16), light green (n = 9) with white borders and alternate green and white (n = 4) with a flat or uneven appearance. The efficacy of these antagonists was investigated by employing the dual plate confrontation assay technique against fungus causing pigeon pea wilt ( Fusarium oxysporum f. sp . udum ) and stem rot of tomato ( Sclerotium rolfsii ). The inhibition zone varied from 46.74 to 100 per cent against F. oxysporum f. sp . udum and the highest inhibition (100%) was exhibited by five T. asperellum isolates. Whereas, the suppression of the Sclerotium was varied from 47.89 to 72.78 per cent. The phylogenetic analysis based on the ITS sequences revealed two distinct clusters, cluster-I (n = 26) and cluster-II (n = 3). To find the diversity, twelve SSR primers were employed and Jaccard’s similarity coefficient was estimated to construct a genetic similarity matrix. The present study has identified five effective native isolates of Trichoderma which can be used against Fusarium and Sclerotium pathogens in the disease management programs.