LAUSR

Abstract This study was carried out to assess in vitro biocontrol efficacy of the Trichoderma aureoviride gamma-induced mutants against three soilborne phytopathogens (Fusarium graminearum, Sclerotinia sclerotiorum and Rhizoctonia solani), and apply rep-PCR analysis for resolving the genetic variations of the wild-type and its mutants. Results showed that different mutants varied in their inhibitory properties towards the tested pathogens and the antifungal activity exerted by the mutants was found to be higher against F. graminearum than R. solani and S. sclerotiorum. Five rep-PCR primers generated different banding patterns and yielded a total of 179 amplified fragments, 170 amplicons (94.97%) were polymorphic. Moreover, the dendrogram based on UPGMA cluster analysis of combined rep-PCR fingerprints differentiated the wild-type from its mutants at 30% similarity level. Five mutants (Tv3(3), Tv2(5), Tv6(5), Tv4(5) and Tv23(6)) showing lowest genetic similarities with the wild-type demonstrated improvement in their biocontrol capabilities as revealed by in vitro assays.