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Title: Discula destructiva, an exotic pathogen of Cornus spp. in North America: evidence of independent introductions

item HADZIABDIC, DENITA - University Of Tennessee
item MANTOOTH, KRISTIE - University Of Tennessee
item BOGGESS, SARAH - University Of Tennessee
item WINDHAM, MARK - University Of Tennessee
item MILLER, STEPHEN - Rutgers University
item Cai, Guohong
item SPATAFORA, JOSEPH - Oregon State University
item ZHANG, NING - Rutgers University
item STATON, MEG - University Of Tennessee
item OWNLEY, BONNIE - University Of Tennessee
item TRIGIANO, ROBERT - University Of Tennessee

Submitted to: International Congress of Plant Pathology Abstracts and Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2018
Publication Date: 7/31/2018
Citation: Hadziabdic, D., Mantooth, K., Boggess, S., Windham, M., Miller, S., Cai, G., Spatafora, J., Zhang, N., Staton, M., Ownley, B., Trigiano, R. 2018. Discula destructiva, an exotic pathogen of Cornus spp. in North America: evidence of independent introductions. International Congress of Plant Pathology Abstracts and Proceedings. 452-P.

Interpretive Summary:

Technical Abstract: Native to North America, Cornus florida (flowering dogwood) and C. nuttallii (Pacific dogwood) are valued for their ornamental characteristics and an important food source for a number of animals due to the high fat content of berries. In the late 1970s, trees on both eastern and western U.S. started declining, resulting in massive die-offs of entire populations. A fungal pathogen, Discula destructiva was identified as the causal agent of dogwood anthracnose. For the next two decades, the pathogen spread throughout most of the native ranges of C. florida and C. nuttallii resulting in high mortality rates. We evaluated genetic diversity and population structure of 93 D. destructiva isolates using 47 microsatellite loci. Our results indicated low genetic diversity and the presence of four genetic clusters that corresponded to two major geographic areas, the eastern United States and the Pacific Northwest, and to the two collection time periods when the isolates were collected (pre- and post-1993). Linkage disequilibrium was present in five out of six subpopulations, suggesting that the fungus only reproduced asexually. Evidence of population bottlenecks was indicated across four identified genetic clusters, and was probably the result of the limited number of founding individuals on both coasts. Our results support the hypothesis that D. destructiva is an exotic pathogen with independent introductions on the east and west coasts of the U.S.