Assessment of the Utility of ISSR Markers for Evaluating Genetic Relationships Among Members of Asimina and Annona

Abstract

The genus Asimina has the only temperate representatives of the tropical Annonaceae, or Custard Apple family, and includes eight species that are indigenous to North America. The North American pawpaw Asimina triloba (L.) Dunal has the largest edible fruit native to the United States and is the best-known of these species. The USDA National Clonal Germplasm Repository for Asimina species is located at Kentucky State Univ. (KSU); therefore, assessment of genetic diversity is an important research priority for KSU. The inter-simple sequence repeat PCR (ISSR-PCR) methodology has been used successfully to characterize genetic diversity within and among populations of many plant species. The objective of this study was to assess the utility of ISSR markers in evaluating genetic relationships in members of the Asimina genus, as well as closely related tropical relatives in the Annona genus. Leaf samples were collected from three plants each of Asimina longifolia, A. obovata, A. parviflora, A. reticulata, A. tetramera and A. triloba. Leaf samples were also collected from three plants each of Annona cherimola, A. squamosa, A. reticulata, A. muricata, A. glabra, A. diversifolia, and A. montana. DNA was extracted from leaf samples and subjected to ISSR-PCR using the REDExtract-N-Amp™ Plant PCR Kit. DNA samples were screened with ISSR primers using the Univ. of British Columbia microsatellite primer set #9. Three primers, UBC812, UBC841, and UBC873 were found to produce 84 scorable ISSR markers and allowed the determination of genetic relationships among Asimina and Annona members examined.