Towards assessing the genetic diversity and occurrence of Trichoderma species from the Indian region of Indo-Burma Biodiversity hotspot, a total of 193 Trichoderma strains were isolated from cultivated soils of nine different districts of Manipur comprising 4 different agroclimatic zones. The isolates were grouped based on the morphological characteristics. ITS-RFLP of the rDNA region using three restriction digestion enzymes: Mob1, Taq1, and Hinf1, showed interspecific variations among 65 isolates of Trichoderma . Based on ITS sequence data, a total of 22 different types of representative Trichoderma species were reported and phylogenetic analysis showed 4 well-separated main clades in which T. harzianum was found to be the most prevalent spp. among all the Trichoderma spp. Combined molecular and phenotypic data leads to the development of a taxonomy of all the 22 different Trichoderma spp., which was reported for the first time from this unique region. All these species were found to produce different extrolites and enzymes responsible for the biocontrol activities against the harmful fungal phytopathogens that hamper in food production. This potential indigenous Trichoderma spp. can be targeted for the development of suitable bioformulation against soil and seedborne pathogens in sustainable agricultural practice.
Pythium aphanidermatum is one of the common causal pathogen of damping-off disease of beans (Phaseolus vulgaris L.) grown in Manipur. A total of 110 indigenous Trichoderma isolates obtained from North east India were screened for their biocontrol activity which can inhibit the mycelial growth of P. aphanidermatum, the causal organism of damping-off in beans. Out of the total isolates, 32% of them showed strong antagonistic activity against P. aphanidermatum under in vitro condition and subsequently 20 best isolates were selected based on their mycelial inhibition capacity against P. aphanidermatum for further analysis. Different biocontrol mechanisms such as protease, chitinase, β-1,3-glucanase activity, cellulase and production of volatile and non-volatile compounds were also assayed. Based on their relative biocontrol potency, only three indigenous Trichoderma isolates (T73, T80 and T105) were selected for pot culture experiment against damping-off diseases in common beans. In greenhouse experiment, Trichoderma isolates T-105 significantly reduced the pre- and post-emergence damping-off disease incidence under artificial infection with P. aphanidermatum and showed highest disease control percentage.
Trichoderma is one of the best known and well described biocontrol fungi for its lytic activity and antagonistic properties against phytopathogens. In the present study, a total of 114 isolates of Trichoderma were isolated from the soil collected from diverse climatic conditions of Manipur on selective medium. Out of the total isolates, 80% shows high degree of antagonism against Fusarium oxysporum while 68% Trichoderma isolates gives strong activity against Rhizoctonia solani . Based on their antifungal activity in dual plate assay, 25 isolates were selected for further analysis. The interaction between the Trichoderma and fungal pathogens were examined microscopically. Several biocontrol mechanisms were studied and analysis data showed that the clearing zone diameter of protease activity of these indigenous Trichoderma isolates ranges from 10 to 60 mm. Among them, 84% gave high chitinase activity and their activity ranges between 10 to 85 mm. whereas, s-1,3-glucanases activity showed a clearing zone diameter ranging from 10 to 70 mm. Based on their relative biocontrol potency, three indigenous Trichoderma isolates (T10, T17 and T83) were selected for pot culture experiment for testing their biocontrol efficacy against wilting and damping off diseases of common beans. Among all the treatments, T83 showed better biocontrol efficacy against the two test fungus as compared to the exotic Trichoderma harzianum (ITCC No. 6276) strain. Keywords: Antagonistic, Chitinase, Fusarium oxysporum , protease, Rhizoctonia solani , Trichoderma sp
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