|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.