Construction of transgenic Trichoderma koningi with chit42 of Metarhizium anisopliae and analysis of its activity against the Asian corn borer.

The chit42 gene was cloned from Metarhizium anisopliae CY1 and was inserted into Trichoderma koningii T30 genome by protoplast transformation. Sixteen transgenic isolates were identified by polymerase chain reaction analysis. The chit42 gene was 1275 bp in length and its coded protein was approximately 42 kDa in size. Semi-quantitative RT-PCR analysis and the measurement of the chitinase activity under induced conditions were conducted. Mortality of the Asian corn borer (Ostrinia furnacalis) was used for assessing efficacy of culture filtrates and conidial suspensions of transgenic Trichoderma strains against the insect. The results indicated that the transgenic Trichoderma strain harboring chit42 gene from Metarhizium anisopliae CY1 showed significant lethal effect on the Asian corn borer larvae. Study on growth inhibition of silkworm (Bombyx mori) larvae was carried out. The transgenic Trichoderma could better hinder the growth and development of the silkworm larvae than the wild-type Trichoderma did. The inhibition to the expression of three genes associated with development and anti-stress response in the mid-gut of the Asian corn borer larvae was more significant in the transcriptional level after larvae were fed with transgenic biomass than with the wild type. Evaluation of inhibition on the growth of maize ear rot pathogens was carried out in vitro test and the transgenic strains kept antagonistic activity against Fusarium verticilloides.