Evaluation of some fungal biocontrol efficiency in relation to their chitinase induction potential

Six fungal biocontrol agents (FBAs) were tested for heir efficiency against some cucurbitaceous damping-off pathogens, vitro and in vivo (under greenhouse condition). The highest fection reduction percetage was realized by the FBA Trichoderma arzianunz and Trichoderma koningii. Alternaria alternata, Fusarium lani, Pythium ultimum and Macrophomina phaseolina were more ensitive to FBAs treatment, especially with T. harzianum than the ther tested damping-off pathogens, where infection reduction rates ere 51.72 to 68%, compared with control. On the other hand, tzoctonia solani was the most tolerant among the tested pathogens ainst the effect of any FBAs applied in vitro and in vivo (infection eduction rate was 28.13% of control). Amendment of the untreated culture with 2% chitin resulted in Ignificant chitinase activities, particularly with T, harzianum (44.96 unit/cm). The presence of the tested pathogens in the growth media, chitinase activities significantly increased in all FBA/pathogen combinations, except for P. ultimum. The highest chitinase activities were induced by T. harzianum against M. phaseolina, F. solani and Sclerotinia sclerotiorum (56.48 - 59.89 unit/ml). Electrophotometric analysis of protein of the tested FBAs using SDS-PAGE technique revealed 6 bands from T. harzianum and T viride, 5 bands for T koningii, 4 bands for T aureoviride and only three bands for Gliocladium roseum. SDS-PAGE polypeptide analysis indicated the presence of 7 bands in T. harzianum and T.viride, 6 bands from T, koningi, 5 bands from T. aureoviride and G. roseum and only 4 bands from T. longibrachiatum. The results obtained suggested high correlation between mycoparasitic effeciences of the tested FBAs and their chitinase activities against the tested pathogens and as well as their molecular weight of protein.