2018 ASHS Annual Conference

Pawpaw [Asimina triloba (L.) Dunal] is a tree fruit native to Eastern North America in its initial stages of commercial production in the United States. Annonaceous acetogenins are long chained fatty acids contained in pawpaw fruit and vegetative tissues, which display pesticidal and anti-tumor properties. Kentucky State University (KSU) is the site of the USDA Repository for pawpaw species, and germplasm evaluation and collection are program priorities. Fruit is a major biomass source for acetogenin extraction; however, it takes 5 to 8 years for a tree to mature and produce fruit. Comparing annonaceous acetogenin activities can possibly allow breeding programs to focus directly on breeding a desired level of acetogenin activity in pawpaw trees. In this study we aim to determine if there is a correlation between annonaceous acetogenin activity in varieties of ripe pawpaw fruits and twigs. Pawpaw fruit and twigs were collected from individual trees of pawpaw varieties and advanced selections (Sunflower, Hi 7-5, Hi 4-1, Susquehanna, and PA Golden) with known and unknown fruit acetogenin activity. 2.5 grams of dried twig tissue were extracted with 25 ml of 95% ethanol and 10 grams of frozen fruit pulp were extracted with 25ml of 95% ethanol. Concentrated extract was transferred to vials to correspond to 5, 10, and 50 ppm concentrations for pulp extracts and vials containing 0, 1.0, 5.0, 10, and 15 ppm concentrations of twig extracts. There were replicates for each concentration. A brine shrimp test (BST) was used to compare mortality in both twig and pulp for each variety and they all showed varying degrees of mortality which indicate acetogenin activity in the varieties. Results suggest that twig extract activity can be used to identify pulp activity in pawpaw fruit of the same variety and high twig activity indicates high fruit activity.