Alteration in the antifungal metabolite production of tebuconazule tolerant mutants of Trichoderma viride
Abstract:Using UV and ă -rays,mutants of Trichoderma viride Pers.ex F.Gray (a mung bean rhizosphere isolate;antagonistic to root rot pathogen Macrophomina phaseolina :sensitive to tebuconazole at 20 ppm) tolerant to tebuconazole were obtained.The mutant ’s viz;UMT1A and UMT4 (tolerant to 50 ppm tebuconazole)and UMT1 and GMT2 (tolerant to 100 ppm tebuconazole)showed wide variations in morphological,physiological and biochemical parameters.Among the biochemical characters the ability to produce antifungal metabolite by these mutants is of significance as they are involved in the biological control of plant pathogens.Mutant GMT2 significantly suppressed the radial growth and sclerotial production of M.phaseolina .The antifungal metabolites were extracted from 15-,30-and 60-day-old culture filtrates of T.viride mutants grown in potato dextrose broth.The extracts were fractionated using thin layer chromatography.The UV-sensitive spots were separated and eluted with ethyl acetate and tested for antifungal activity on M.phaseolina .There were four distinguishable fractions in 15-day-old culture, filtrate of wild type but the tolerant mutants lacked one or other fraction found in the wild type.A common fraction (Rf:0.60)was obtained from all the three UV induced mutants that gave significantly more inhibition (28 –30%)than others (20 –26%).The 30-day-old culture filtrate yielded three fractions in wild type and in UMT4,whereas other mutants lacked one or other fraction that was detected in wild type.The fraction from GMT2 (Rf:0.61)showed significantly greater inhibition of the growth of M.phaseolina (30%)than other mutants (11 –20%).From 60-day-old culture filtrate two fractions (Rf:0.17 and 0.61)were obtained from all the strains except GMT2 that yielded only one fraction (Rf:0.61).The fraction from wild type and UMT1 caused more inhibition (34 and 33%,respectively)than other fractions (14 –29%).
Document Type: Research Article
Publication date: 1999-12-10
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