This collaborative project between Michael Milgroom, Cornell University, and Wang Kerong, Nanjing Agricultural University, Nanjing, China, will compare the genetic diversity and population structure of the chestnut blight fungus and its virus-like double-stranded RNA (dsRNA) parasites in China and the US. At least eight populations in China will be sampled, and using molecular genetic markers identified in previous studies, fungal isolates from each population will be analyzed for genetic variability. The extent of population subdivision will be determined, from which inferences can be made about gene flows among fungus populations. Fungal isolates from China will be screened for dsRNAs in order to estimate prevalence in Chinese populations. The chestnut blight fungus was introduced into the US from China at the turn of the century and devastated the previously abundant chestnut forests in the eastern US. Studying the fungus populations at their source in China is an opportunity to understand the basic factors that affect the population biology of this species in a long-established, relatively stable population. This study is also expected to be useful for the development of a biological control program of the fungus.
