PGRU Internship Showcase
About our Interns' Summer Projects:
Lindsay Brown (2019) – Cornell University
Effect of Powdery Mildew Resistance on Phenolic Content of Inoculated Vitis Leaves
Genetic resistance to the economically damaging powdery mildew (Erysiphe necator) can improve the sustainability of viticultural control measures as demonstrated through the Ren3 and Ren9 resistance genes. These genes trigger a hypersensitive response in tissues affected by powdery mildew and associated changes in the concentration of phenolic compounds. Phenolics are defensive compounds which may prevent the spread of powdery mildew throughout the impacted vines. However, the post inoculation relationship between the genotypes of interest and the phenolics is not fully understood. This experiment analyzed the phenolic concentrations of leaf tissue samples from an interspecific hybrid population of 103 individuals with both, either, or neither of these resistance genes at 8 days post inoculation with HPLC to examine the relationship between the phenolic concentration and the genotypes. HPLC showed three main peaks: a catechin, a hydroxycinnamic acid derivative, and a quercetin. The impact of the genotype on the phenolic content was analyzed and will be discussed in the poster. Moving forward, HPLC analysis with time trials consistent to the main points of phenolic change in the literature would prove most effective to fully understand the metabolite changes related to the Ren3 and Ren9 genotypes.
Molly Carroll (2019) – Perdue University
Quantitative determination of anthocyanin compounds during tart cherry maturation.
With increasing interest in foods with antioxidant, anti-inflammatory, and other health properties, fruit with rich phenolic and anthocyanin profiles are in greater demand by consumers. Tart cherries (Prunus cerasus) have unique nutritional qualities, relative to sweet cherries, which contribute to human health. However, dietary consumption of tart cherries as juice or processed fruit in the U.S. is largely based on one variety, ‘Montmorency’. Studying the diversity of the tart cherry species would allow for more insight into how this fruit can be better used to improve human health and preserve the genetic variance within the species. High Performance Liquid Chromatography (HPLC) was used to track anthocyanin and phenolic compounds in 19 varieties of tart cherry, during maturation. Samples of leaves and fruit were collected at four increments throughout the ripening period of the fruit to analyze how anthocyanin production progresses. It was found that relevant anthocyanin compounds to the tart cherry profile were accumulated or degraded, depending on the compound, throughout the ripening process. This change in quantity was constant. The phenolic profile of the leaves had very small changes throughout fruit maturation, so therefore serve as a control. This study serves as the beginning of a much larger exploration into the genetic and phenolic diversity of tart cherries.
Lindsay Lesniak (2019) – Hobart and William Smith Colleges
Understanding grapevine (Vitis) domestication and variation between Vitis species through analysis of polyphenolic and aromatic compounds
The evolution of grapes (Vitis species) has resulted in nearly sixty species of Vitis worldwide, varying in physical and chemical characteristics, including, disease resistance, antioxidant concentration, color, sweetness, acidity and the focus of this research, aromas. Human use of grapes has narrowly focused on the domesticated grapevine, Vitis vinifera. Wild North American species Vitis labrusca are used for grape breeding with distinct foxy aromas (such as ‘Concord’), but not always favored in wine production. V. vinifera cultivars however, have promised more successful hybrid crosses because of their floral and apple-like aromas due to the presence of aromatic compounds such as, 2-Hezenal and acetic acid. By studying aromatic compounds in a diverse collection of grapes from the USDA grape collection in Geneva, New York and the UC Davis Grape Repository in Davis, California, the complex domestication history and how Vitis species differ at the biochemical level can be better understood. The accessions were preselected based on foxy or Muscat aromas and analyzed by grouping into V. vinifera, V. labrusca, and Vitis hybrids. GC-MS indicated the presence of major aromatics in conjunction with titratable acidity and soluble solids (Brix) to measure pH and sugar content of individual accessions. This study can aid the wine and table grape industry in yielding the best quality product that not only have favorable and diverse physical properties but also beneficial nutritional properties. Additionally, it provides a bridge between the V. vinifera species grown in Western United States at UC Davis and the hybrid accessions bred in the Northeast at the Geneva repository.
Kyra Battaglia (2019) – University of Rochester
Characterization of the USDA Tart Cherry (Prunus cerasus) Collection in Geneva, NY
The sweet cherry, Prunus avium, and tart cherry, Prunus cerasus, are the two major cherry species grown commercially. In comparison to sweet cherries, tart cherries have high acidity and softer fruit. Additionally, the tart cherry anthocyanins (red pigments in fruit) differ from sweet cherry and have reported benefits to human health. This experiment looked at the various characteristics of cherry fruit quality important for commercial purposes, including fruit weight, flesh to pit ratio, acidity, total soluble solids, aromatic compounds, and anthocyanin content. To evaluate diversity of fruit quality, ripe cherries were collected from the USDA Tart Cherry Collection in Geneva, NY in 2011, 2013, 2014, and 2019. The USDA collection maintains 130 tart cherry accessions across 7 species. Cherries were weighed, pitted, and weighed without pits. The cherries were juiced to determine the total soluble solids (TSS) using a refractometer, the malic acid concentration, and the presence of different aromatic compounds using gas chromatography-mass spectrometry (GC-MS). The samples were also prepared and processed using High Performance Liquid Chromatography (HPLC) to determine the anthocyanin concentration. This diversity project showed the relationship of other cherry species in relation to Montmorency, the main cherry sold for commercial purposes, with others containing more favorable traits. Analysis also showed characteristic and phenolic comparisons between tart and sweet cherries. This information will be publicly available through the Germplasm Resources Information Network (GRIN-Global), providing accession data for future research and development of cultivars with optimal characteristics.
Kayla Aulet and Kenisha Ross (2018) – Hobart and William Smith Colleges
Comparison of anthocyanin levels in the USDA Tart Cherry Collection
Tart cherries (Prunus Cerasus) have an abundance of anthocyanins, which is a compound that has many antioxidant properties, and consequently also has many health benefits. Industries that utilize tart cherries tend to only use one cultivar, Montmorency. The two major anthocyanins present in tart cherries are cyanidin 3 -glucosylrutinoside and cyanidin 3 -rutinoside. Anthocyanins from tart cherries collected in 2011, 2013 and 2014, as well as sweet cherries from 2018 and commercial juice were extracted and put into an HPLC machine. The area from the corresponding peaks of both anthocyanins on the chromatograms were converted into concentrations and then analyzed. For two years Almaz O.P had the highest concentrations of anthocyanin levels, while Montmorency had the least for rutinoside and M-209 had the least amount of levels for glucosylrutinoside. Commerical juice levels of both anthocyanins decreased the closer the juice bottles got to their expiration dates. This research demonstrates that cultivars other than Montmorency can have the same if not more health benefits and marketable properties. Anyone with interests in the health benefits of cherries should expand the types of cultivars they use.