The Impact of Pawpaw Patch Genetic Diversity and Clonality On the Incidence of Invasive Species.

Native North American pawpaw (Asimina triloba) patches serve an important role in forest ecosystems and stream and rivers in terms of fruit production for animals, soil erosion control, enhancing insect biodiversity, and possibly resisting establishment of invasive plant species. Pawpaw is also in the early stages of commercial production with a fruit that has a tropical like flavor similar to a blend of mango, pineapple, and banana.  The objectives of this study were to determine 1) the genetic diversity and clonality displayed in native pawpaw patches, and 2) if patches reduced the incidence of invasive species. Twenty-five trees from seven Kentucky patches in the Bluegrass region were sampled for genetic analysis. Leaf samples were extracted using the DNAmite Plant Extraction Kit and products from four microsatellite loci were analyzed using a 3130 Applied Biosystems Gene sequencer.  String grids were created and invasive plants counted in three 5 meter squares in each of the patches and control plots outside of each patch. Soil ph in all plots was approximately 6.0. The number of plants for each invasive species within pawpaw patches was counted and compared to control plots. Pawpaw patches displayed high genetic diversity among populations.  All patches showed clonality to some degree in transects of patches.  Amur honeysuckle (Lonicera maackii ), garlic mustard (Alliaria petiolata), and winter creeper (Euonymus fortunei) were found in most locations. Analysis showed that two patches had significantly fewer honeysuckle plants inside each pawpaw patch than outside the patch, and a third patch displayed a trend to have fewer honeysuckle bushes present inside the patch. A fourth patch had similar numbers of honeysuckle within and outside the patch. Additional patches at different locations and higher honeysuckle pressure will be required to further test whether pawpaw patches reduce the incidence of honeysuckle bushes.