Following fungal transformation, ten drug-resistant colonies were randomly selected and the putative transformants were verifiedby PCR to detect the integration of Tyr gene in the genome. Single spore isolates (at least five for each transformant) were acquired and subcultured for five generations. After preliminary assays of genetic and phenotypic stabilities, a transformant (designated GT) was selected and used for subsequent analysis. Successful expression and transgenic stability of the Tyr gene were confirmed by RT-PCR analysis (Fig. 1A)