Agrobacterium tumefaciens-mediated transformation of SOD gene to Trichoderma harzianum

Trichoderma harzianum is a soil-borne filamentous fungus that exhibits biological control properties because it parasitizes a large variety of phytopathogenic fungi. In this study the SOD gene was successfully transferred into the bio-control fungus Trichoderma harzianum with an efficiency of 60-110 transformants per 10⁷ spores by using Agrobacterium tumefaciens-mediated transformation. Putative transformants were analyzed to test the transformation by the southern blot. Antifungal activities of the transformants were examined under abiotic stresses. The transformants were exposed to 40°C for three days and 2 mol/l NaCl at 27°C for 5-10 days to assay antifungal activities with Sclerotinia sclerotiorum. The inhibition rates of the transformants, comparing to Trichoderma harzianum with no SOD gene transferred, were respectively 83.96% after 40°C and 60.13% after 2 mol/l NaCl. The results showed that the SOD transformants had significantly higher resistance to heat and salt stress.