Inhibition of plant-pathogenic fungi by a corn trypsin inhibitor overexpressed in Escherichia coli

The cDNA of a 14-kDa trypsin inhibitor (TI) from corn was subcloned into an Escherichia coil overexpression vector. The overexpressed TI was purified based on its insolubility in urea and then refolded into the active form in vitro. This recombinant TI inhibited both conidium germination and hyphal growth of all nine plant pathogenic fungi studied, including Aspergillus fl avus, Aspergillus parasiticus, and I;Fusarium moniliforme. The calculated 5 0% inhibitory concentration of TI for conidium germination ranged from 70 t o more than 300 mu g/ml, and that fur fungal growth ranged from 33 to 124 m u g/ml depending on the fungal species. It also inhibited A. flavus and F. moniliforme simultaneously when they were tested together, The results sugg est that the corn 14-kDa TI may function in host resistance against a varie ty of fungal pathogens of crops.