Kentucky State University

Poster Title

Determining a Correlation for North American Pawpaw Acetogenin Activity between Twig and Ripe Fruit as Determined by the Brine Shrimp Test

Institution

Kentucky State University

Abstract

The North American pawpaw is a tree fruit native to Kentucky. Annonaceous acetogenins are long chained fatty acids contained in pawpaw fruit and vegetative tissues which display pesticidal activity, possibly representing a new botanical pesticide for agronomic pest control. 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, 5 to 8 years are required for a tree to mature and produce fruit. Early detection of high acetogenin fruit selections would shorten the pawpaw breeding cycle. The objective of this study was to determine if there is a correlation between acetogenin activity in ripe fruit and twig tissues. Twigs fruit were collected from trees of pawpaw varieties and advanced selections (Mitchell, Overleese, NC-1, Susquehanna, Zimmerman, Wells, Wabash, Sunflower, G4-25, Hi4-1, and Hi7-5) that vary from high to low in fruit acetogenin activity. Two and one half grams of dried twig tissue or ten grams of frozen fruit pulp were extracted with 95% ethanol and the brine shrimp test (BST) was employed to assess acetogenin activity in extracts. Concentrated extract was transferred to vials to correspond to 0, 0.5, 1.0, 5.0, and 10 ppm concentrations for twig and 5, 10, 20, and 50 ppm concentrations for pulp with three replicate vials per concentration. There was a negative linear correlation (R2 = 0.57) between the twig BST mortality at 20 ppm of extract and pulp LC50, indicating a useful relationship.

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Determining a Correlation for North American Pawpaw Acetogenin Activity between Twig and Ripe Fruit as Determined by the Brine Shrimp Test

The North American pawpaw is a tree fruit native to Kentucky. Annonaceous acetogenins are long chained fatty acids contained in pawpaw fruit and vegetative tissues which display pesticidal activity, possibly representing a new botanical pesticide for agronomic pest control. 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, 5 to 8 years are required for a tree to mature and produce fruit. Early detection of high acetogenin fruit selections would shorten the pawpaw breeding cycle. The objective of this study was to determine if there is a correlation between acetogenin activity in ripe fruit and twig tissues. Twigs fruit were collected from trees of pawpaw varieties and advanced selections (Mitchell, Overleese, NC-1, Susquehanna, Zimmerman, Wells, Wabash, Sunflower, G4-25, Hi4-1, and Hi7-5) that vary from high to low in fruit acetogenin activity. Two and one half grams of dried twig tissue or ten grams of frozen fruit pulp were extracted with 95% ethanol and the brine shrimp test (BST) was employed to assess acetogenin activity in extracts. Concentrated extract was transferred to vials to correspond to 0, 0.5, 1.0, 5.0, and 10 ppm concentrations for twig and 5, 10, 20, and 50 ppm concentrations for pulp with three replicate vials per concentration. There was a negative linear correlation (R2 = 0.57) between the twig BST mortality at 20 ppm of extract and pulp LC50, indicating a useful relationship.