BIOLOGICAL AND MOLECULAR CHARACTERIZATION OF POTENTIAL BIOCONTROL STRAINS OF TRICHODERMA

Thirty-four strains of seven species of Trichoderma isolated from vari ous fungal sources were compared for direct mycoparasitic activity (MP A), chitinase production and antibiotic activity (ANA) in order to cho ose the most appropriate partners for a strain-breeding programme. Wit hin species genetic differences were also assesses in T. hamatum, T. h arzianum and T. viride by means of random amplification of polymorphic DNA (RAPD). Endochitinase activities of the Trichoderma strains range d between 20.4 and 1264.5 units/g dry weight of mycelium. The correlat ion between MPA and chitinase activity was not unambiguous and no corr elation existed between MPA and ANA. The RAPD patterns of T. viride st rains were highly variable, while isolates of T. harzianum proved to b e more uniform; T. hamatum revealed remarkable intraspecific divergenc e. All these three comprised certain pairs of strains that are promisi ng participants of a strain-improving programme, since their strong ge netic affinities offer good changes for combining their contrasted bio control traits.