Image Credit: David H. Gent
Image Credit: David H. Gent
Podosphaera macularis (Wallr.) U. Braun & S. Takam. is an obligate parasite and causal agent of the economically damaging disease powdery mildew of hop (Humulus lupulus L.). The host range of P. macularis also includes Japanese hop (Humulus japonicus Siebold & Zucc. syn. H. scandens) and hemp (Cannabis sativa L). Podospharea macularis is widespread on cultivated, wild, and feral hop plants in the Northern Hemisphere, but also occurs on cultivated hop in a limited number of countries in the Southern Hemisphere. Developing hop cultivars resistant to powdery mildew is a major focus of hop breeding programs where the disease occurs. Podosphaera macularis displays pathogenic variation and in some instances has adapted quickly to disease resistance in hop cultivars. Isolate HPM-609 possesses virulence that enables this isolate to infect hop cultivars that contain the powdery mildew resistance genes dubbed Rb, R3, R4, R5, and R6. The P. macularis genome will help reveal genetic factors associated with pathogenicity, host-specific virulence, and enable development of improved diagnostic assays to detect the pathogen.
