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Mutagenic strain development of Trichoderma harzianum to enhance antagonism against soil borne plant pathogens and its commercialization
A. HANNAN (1), M. J. Saleem (2), S. T. Sahi (3), K. Riaz (1). (1) Univ of Agriculture Faisalabad, Faisalabad, Pakistan; (2) University of the Punjab Lahore Pakistan, Lahore, Pakistan; (3) University of Agriculture Faisalabad, Faisalabad, Pakistan

<i>Trichoderma harzianum</i> has antagonistic potential against numerous soil borne plant pathogens. Present study was an effort to commercialize hyperactive mutants of <i>T. harzianum.</i> For this purpose 28 strains of <i>T. harzianum</i> were purified and screened for antagonistic efficiency against <i>Fusarium oxysporum, Alternaria alternata, Macrophomina phaseolina </i>and <i>Rhizoctonia solani.</i> The data revealed that strains (Th<sub>S3</sub>, Th<sub>S6</sub> and Th<sub>S17</sub>) isolated from rhizosphere of vegetable crops showed higher percentage of reduction in colony diameter over control (36.5, 38.0 and 37.5% respectively). The efficient strains were mutated through ultra violet irradiations and chemicals. The mutants survived on minimal inhibitory concentration of benomyl (mutant detector) were re-evaluated, where efficient individuals (48.5, 52.5 and 52%) were retained for genetic characterization. Band expression of mutants and parental strains exhibited isogenic variant of parental strains and their outperformance could be attributed to modified genetic make-up. Moreover these hyperactive mutants were characterized for conidial yield on cheaper substrates under solid state fermentation. The conidial count was higher on rice bran supplemented with chick pea flour (2.5 x 10<sup>8</sup> cfu/g after 12 days of incubation at 27ºC. These findings explored a cost effective technology for production of hyperactive mutants of <i>T. harzianum</i> at pilot scale.

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