Using Molecular Markers to Determine Clonality of Native Pawpaw Patches

Pawpaw [Asimina triloba (L.) Dunal] is a tree fruit native to areas in the Midwest and Southeast United States. Since 1994, Kentucky State University (KSU) has served as the USDA National Clonal Germplasm Repository, or gene bank, for pawpaw; therefore, the assessment of genetic diversity in pawpaw is an important research priority for the KSU program. Pawpaw is usually found as an understory tree, often found in large patches. Pawpaw tend to form many root suckers and it has been suggested that most pawpaw patches are therefore clonal in nature. Leaf samples were collected from trees in three native patches in central Kentucky. The objective of this study will be to utilize simple sequence repeat (SSR) markers with DNA extracted from leaf samples to determine if fingerprint patterns indicate that all trees sampled in the patch are clones. DNA was extracted from leaves of ten trees each from three patches in Kentucky. Using the SSR primer B103, polymorphisms were detected among the three patches with product sizes ranging from 280-600 base pairs (bp). One tree in patch one showed two polymorphic markers, one at 360 bp and the other at 600 bp, indicating the patch was not clonal