Biological Characteristics and Assessment of Virulence Diversity in Pathosystems of Economically Important Biotrophic Oomycetes

AbstractPlant biotrophic oomycetes cause significant production problems and economic losses in modern agriculture and are controlled by fungicide applications and resistance breeding. However, high genetic variability and fast adaptation of the pathogens counteract these measures. As a consequence of the “arms race,” new pathogen phenotypes recurrently occur and may rapidly dominate the population when selected through the pressure of control measures. Intensive monitoring with fast and reliable identification of virulence phenotypes is essential to avoid epidemics and the economic consequences in agriculture. For some of the most important downy mildews and white blister rusts, bioassay-based differentiation has been established to classify infectivity of field isolates or cultivated strains on hosts of defined resistance. However, the testing is laborious, time-consuming, logistically demanding, and prone to impreciseness. Alternatively, host independent classification could overcome these problems and...