ARS | Publication request: Genetic Diversity of Flowering Dogwood (Cornus florida L.) in the Southeastern United States Using Microsatellites

Submitted to: Society for the Study of Evolution
Publication Type: Abstract Only
Publication Acceptance Date: June 24, 2008
Publication Date: June 24, 2008
Citation: Wang, X., Fitzpatrick, B.M., Rinehart, T.A., Ownley, B.H., Trigiano, R.N. 2008. Genetic Diversity of Flowering Dogwood (Cornus florida L.) in the Southeastern United States Using Microsatellites. Society for the Study of Evolution.

Technical Abstract: Cornus florida L. (Flowering dogwood) is a small tree indigenous to the eastern United States (Fig. 1) in the understory of temperate deciduous forests. The flowers, leaves, bark and fruits provide nourishment for a variety of vertebrates and berries contain high fat (approximately 18%) as well as high levels of available calcium (1;4). Flowering dogwood is an obligate outcrossing species and recent study provided an evidence of gametophytic self incompatibility (13), and coupled with the inability to hybridize, maintains high genetic variability in native populations. In the past two decades, flowering dogwoods have been severely affected by powdery mildew caused by Erysiphe pulchra (Cook & Peck, Braun & Takamatsu) and dogwood anthracnose caused by Discula destructiva Redlin (12) (Fig. 2). Mortality of flowering dogwood caused by dogwood anthracnose has ranged from 48-98% in the northeast and Appalachian highlands (5; 6; 9; 14; 16). With extensive loss of numerous individuals from the population, we hypothesized that some genetic diversity may have been lost. However, it may take many generations for the full genetic effect of a population bottleneck to manifest itself (2;8). In addition, genetic variation may be maintained in widespread species despite rangewide declines because alleles that are lost in one locality may be preserved in others. In this case, genetic variation among sites increases and historical patterns of geographic variation are disrupted. The objective of this project is to assess the genetic diversity of flowering dogwood in the southeastern United States using microsatellite loci (SSRs). 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.