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Title: Analysis of genetic diversity of flowering dogwood natural stands using microsatellites the effects of dogwood anthracnose

item HADZIABDIC, DENITA - University Of Tennessee
item FITZPATRICK, B - University Of Tennessee
item WANG, X - Texas Agrilife Research
item WADL, P - University Of Tennessee
item Rinehart, Timothy - Tim
item OWNLEY, B - University Of Tennessee
item WINDHAM, MARK - University Of Tennessee
item TRIGIANO, R - University Of Tennessee

Submitted to: Genetica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2010
Publication Date: 9/4/2010
Citation: Hadziabdic, D., Fitzpatrick, B., Wang, X., Wadl, P., Rinehart, T.A., Ownley, B., Windham, M., Trigiano, R. Analysis of genetic diversity of flowering dogwood natural stands using microsatellites the effects of dogwood anthracnose. Genetica. 138(9):1047-1057. 2010.

Interpretive Summary: In the past three decades, flowering dogwoods have been severely affected by dogwood anthracnose and powdery mildew caused. Poor seed production due to decreased flowering and higher susceptibility of smaller, younger trees resulted in reduced dogwood regeneration and significant decline of native dogwood populations. Mortality of flowering dogwood caused by dogwood anthracnose has ranged from 48-98% in the northeast and Appalachian highlands. In 1992, a tree survey in the Great Smoky Mountain National Park revealed that 25% of flowering dogwoods had been killed by dogwood anthracnose. Two years later, an estimated 75% of the remaining trees had been eliminated. Here we asked whether or not variation within and among localities is consistent with the dramatic demographic effect of anthracnose observed over the northern portion of the range of C. florida. We make use of extensive sampling from southern portions of the range, where no anthracnose has been detected. Young leaves or flower buds of C. florida were collected in the spring of 2006 from 234 individuals at 46 locations throughout the southeastern United States. Samples were scored for 18 polymorphic microsatellites. These samples were taken 28 years, or approximately four generations, after the first appearance of anthracnose in New England.

Technical Abstract: Flowering dogwood (Cornus florida) populations recently have experienced severe declines caused by dogwood anthracnose. Mortality ranged from 48-98%, raising the concern that genetic diversity has been reduced significantly. Microsatellite data was used to evaluate the level and distribution of genetic variation throughout much of the native range. Genetic variation in areas affected by anthracnose was as high or higher than areas without die-offs. We found evidence of four widespread, spatially contiguous genetic clusters. However, there was little relationship between geographic distance and genetic difference. These observations suggest that high dispersal rates and large effective population sizes have so far prevented rapid loss of genetic diversity. The effects of anthracnose on demography and community structure are likely to be far more consequential than long-term genetic effects.