Variability in induction of defense response in Bengal gram against Trichoderma species.

摘要

Ten isolates of Trichoderma spp., collected from diverse agro-ecological habitat of West Bengal, was evaluated against M. phaseolina to test the in vitro variability in antagonistic potential and also the ability to induce resistance in Bengal gram plant following Trichoderma treatment. T₆ isolate grew rapidly and attained the S₁ stage only on 4 days of incubation followed by T₃, T₄ while T₂ isolate of T. harzianum was the least effective against the pathogen. The T₉ isolates of T. roseum caused highest inhibition (47.41%) of mycelial growth followed by T₇ (44.44%), T₁ (39.63%) against M. phaseolina. Very low volatile substances released by T₁₀ isolate of T. roseum also inhibiting only 19.26% mycelial growth. On the contrary, T₆ and T₁₀ isolates of Trichoderma also showed highest mycelial growth inhibition against the pathogen through production of non-volatile antibiotic at 10% concentration. In the pre-inoculated plant there was an increase in activity of all the defense related enzymes tested as compared to control. T₉ isolate of T. roseum induced highest PAL (4.4U) and beta -1, 3 glucanase activity (272.4U) followed by T₁ isolate of T. viride (4.2U) and T₁₀ of T. roseum (263.6U), respectively. Very low beta -1, 3 glucanase activity (10.88%) was found in inoculation with T₇ isolate. Highest activity of peroxidase was noticed in the plant inoculated with T₁ isolate (174.28U) followed by T₉ (164.28U). Very low activity was found when the plant was inoculated with T₈ isolate. Pre-treatment of the roots of Bengal gram plants with different isolates of Trichoderma spp. was shown to systemically induce different defense related enzymes and the amount varies with the isolates irrespective of species and geographical habitat.