Transgenic potato plants overexpressing the pathogenesis-related STH-2 gene show unaltered susceptibility to Phytophthora infestans and potato virus X.

The STH-2 gene is rapidly activated in potato leaves and tubers following elicitation or infection by Phytophthora infestans. However, its biochemical function remains unknown. In order to ascertain if STH-2 protein is directly involved in the defense of potato against pathogens, the STH-2 coding sequence under the control of the CaMV 35S promoter was introduced into potato plants. Transgenic plants expressing the STH-2 gene were analyzed for an altered pattern of susceptibility to a compatible race of P. infestans and to potato virus X. Results indicate that constitutive expression of the STH-2 gene did not reduce susceptibility of potato to these pathogens.