Transgenic Potato Plants Expressing StoVe1 Exhibit Enhanced Resistance to Verticillium dahliae

Abstract

Verticillium wilt is a persistent and serious disease in potato production mainly caused by soil-borne fungus Verticillium dahliae. In our previous experiment, StoVe1 gene was cloned from Solanum torvum, a wild relative of eggplant which was shown to be highly resistant to fungal wilts. In order to analyze the function of StoVe1 gene, the StoVe1 gene was sub-cloned into vector pCMBIA1304 and the recombination vector was introduced into the potato cultivar Desiree plants by Agrobacterium-mediated transformation. A total of 25 Hygromycin B-resistant plants were generated with ten independent transgenic lines identified by PCR and GUS staining analysis. The expression of StoVe1 gene in transgenic lines C9, C17, and C24 which were selected randomly was examined by quantitative RT-PCR. The resistance of transgenic lines to V. dahliae was also evaluated by in vitro antifungal and in vivo plant infection assays. The result showed that StoVe1 gene revealed its expression in all analyzed lines and the level of the transcript was 5.3- to 9.0-fold of that of the control. The antifungal assay revealed that transgenic lines C9, C17, and C24 had threefold higher than control plants and had higher inhibition rates of 45.5%, 44.5%, and 39.4% respectively. This result was confirmed by plant infection assay and the selected three lines were more resistant to V. dahliae infection, with disease index of 15 to 35, about one half to one fourth of that of the control and disease incidences of 20% to 50% and about one half to one fourth of that in control plants. It revealed that the overexpression of StoVe1 gene in transgenic potato lines enhanced plant resistance to V. dahliae.