Downy mildew is able to carry out its sexual cycle on resistant grape varieties

Abstract

Previous studies have shown that new resistant grape cultivars limit epidemics caused by asexual reproduction of downy mildew. However, until now, there was a lack of knowledge on the sexual phase of the pathogen. This study demonstrates that host resistance has little effect on the sexual cycle of downy mildew. Thus, the pathogen can complete its life cycle (asexual and sexual phases) on partially resistant grapevine varieties. The persistence of pathogen populations on partially resistant varieties from one year to the next represents a major challenge for the sustainability of genetic resistance of grapevines.