DIFFERENTIATION OF A SPECIFIC TRICHODERMA BIOLOGICAL-CONTROL AGENT BYRESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM (RFLP) ANALYSIS

A single biological control isolate belonging to the species aggregate Trichoderma harzianum Rifai was differentiated from other closely rel ated Trichoderma species and commonly isolated mycoflora by molecular assay. Restriction fragment length polymorphism (RFLP) analysis enable d the differentiation of the single isolate; a hybridising band of 1.1 kb being diagnostic. Cross-hybridisation occurred against the DNA fro m 12 Trichoderma isolates, representative of three species aggregates. The hybridisation probe used during the RFLP analysis was an amplific ation product produced during random amplification of polymorphic DNA (RAPD) polymerase chain reaction (PCR) analysis using DNA from T. harz ianum isolate C65 as template. This amplification product was not visi ble following separation of amplification products generated during PC R using DNA from a test array of fungi as template. Diagnostic PCR, us ing primers designed from the sequence of the specific polymorphic amp lification product failed to discriminate between C65 and other Tricho derma isolates, since products with equivalent size were generated. Th e ability to differentiate the isolate of T. harzianum from other clos ely related fungi will enable monitoring of the specific isolate in fi eld trials to assess biological control ability.