Culley, Theresa M. , Hardiman, Nicole .
Crossing Between Scion and Rootstock of Ornamental Trees May Create Wild Populations of Callery Pear (Pyrus calleryana).
Callery Pear (Pyrus calleryana) is an ornamental tree commonly planted in residential and commercial areas but has recently begun to spread into disturbed sites throughout the United States. This species is originally from China and is represented today by at least 25 different cultivars, each of which is propagated by grafting the desired cultivar (the scion) onto P. calleryana rootstock. Previous research has demonstrated that intraspecific hybridization among different cultivars of this self-incompatible species results in fruit set and contributes to the formation of wild populations. It is also possible that crossing between the scion and rootstock, which can sprout following damage or neglect, may result in fruit set and wild offspring. To examine the potential for wild populations to originate from individual grafted trees in this way, we compared the genotypes of scion and rootstock for different cultivated trees planted throughout Southwestern Ohio. Using nine microsatellite loci, we determined that scion and rootstock were genetically different in all cases with a coefficient of relatedness (r) of -0.08. We then examined the self-incompatibility alleles of scion and rootstock using molecular techniques to (1) determine if the two components of the grafted trees were compatible, and (2) ascertain if rootstock genotypes are found in wild populations. All evidence suggests that the scion and rootstock (if allowed to sprout and flower) are able to cross-pollinate and produce fruit. This may be an additional explanation for several reported observations of large invasive Callery Pear populations located around abandoned nurseries in the United States. Thus, crossing within individual Callery Pear trees in addition to crossing between cultivars can lead to the formation of wild populations.
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Culley Lab Website
1 - University of Cincinnati, Department of Biological Sciences, 614 Rieveschl Hall, Cincinnati, Ohio, 45221, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Huron/Hilton
Date: Monday, July 9th, 2007
Time: 3:45 PM