Evaluation of Bio-control and Colonization Potential of Molecular Improved Trichoderma Strains Against Rhizoctonia Diseases of Bean

Biological control of plant diseases is one of the effective strategies to reduce harm effects of pesticides on human health and environment. T. harzianum is one of the most successful biological control agents which have antagonistic activity against many of pathogenic fungi. Biocontrol activity of T. harzianum is linked to the amount and type of hydrolase enzymes. In the authors' previous work, chimeric chitinase was constructed by protein engineering and the recombinant protein was transferred to the T. harzianum. In the present study, the biocontrol activity and colonization of improved isolates were evaluated on bean plant and its pathogen (Rhizoctonia solani) in laboratory and greenhouse. The presence and stability of the chimeric protein was confirmed by molecular technique, after that biocontrol assay was done in dual culture method. The results showed that T3 with 82/53 percent inhibition compared to control, was the best biocontrol in invitro. According to the results of greenhouse tests, plants that were treated with T7, T3 and T15 in all stages of measurement (two leaf, mid-term growth, early reproductive stage and harvest stage) showed symptoms less than 40%. Root surface colonization and fungal hyphae penetration was confirmed by molecular studies using primers PF1/R3xba1.