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Research Project: Genetic Enhancement of Watermelon, Broccoli, and Leafy Brassicas for Economically Important Traits

Location: Vegetable Research

Title: Genetic relationships in Cucurbita pepo (pumpkin, squash, gourd) as viewed with high frequency oligonucleotide–targeting active gene (HFO–TAG) markers

Author
item Paris, H - AGRICULTURAL RESEARCH ORGANIZATION OF ISRAEL
item Faigenboim, A - AGRICULTURAL RESEARCH ORGANIZATION OF ISRAEL
item Reddy, U - WEST VIRGINIA STATE UNIVERSITY
item Donahoo, Ryan
item Levi, Amnon

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2015
Publication Date: 8/15/2015
Citation: Paris, H., Faigenboim, A., Reddy, U., Donahoo, R.S., Levi, A. 2015. Genetic relationships in Cucurbita pepo (pumpkin, squash, gourd) as viewed with high frequency oligonucleotide–targeting active gene (HFO–TAG) markers. Genetic Resources and Crop Evolution. 62:1095-1111.

Interpretive Summary: Cucurbita pepo is an economically important crop, encompasses hundreds of cultivars of pumpkins, squash, and gourds. There is a need by plant breeders and geneticists to explore the genetic diversity and relationships among the different pumpkins and squash varieties collected in different parts of the world and identify valuable gene sequences useful for enhancing disease resistance and quality. In this study, a USDA, ARS scientist developed a unique type of DNA markers named “high frequency oligonucleotides-targeting active genes” (HFO-TAG) that proved to be a useful tool in identifying differences in gene sequences. In this study, the scientist collaborated with other scientists at the Agricultural Research Organization (ARO), Israel, and at West Virginia State University on evaluating genetic diversity among pumpkin and squash varieties. The genetic information produced in this study should be useful for seed companies, plant breeders and University scientists and students interested in improving disease resistance and fruit quality of pumpkin and squash.

Technical Abstract: Cucurbita pepo is a highly diverse, economically important member of the Cucurbitaceae. C. pepo encompasses hundreds of cultivars of pumpkins, squash, and gourds. Although C. pepo has been scrutinized with various types of DNA markers, the relationships among the cultivar-groups of C. pepo subsp. pepo, the more widely grown subspecies, have not heretofore been adequately resolved. We assessed genetic relationships among 68 accessions of Cucurbita pepo, including 40 from C. pepo subsp. pepo, using polymorphisms in 539 high-frequency, oligonucleotide–targeting active gene (HFO–TAG) fragments, most of which represent coding regions of the genome. Genetic distance values (GDs) were calculated, a dendrogram was constructed, and principal component analyses were conducted. The GDs clearly demarcated the four edible-fruited cultivar-groups of C. pepo subsp. pepo, Cocozelle, Pumpkin, Vegetable Marrow, and Zucchini. Furthermore, the results indicate that the Old World pumpkins as well as the long-fruited cultivar-groups of C. pepo subsp. pepo (cocozelle, vegetable marrow, and zucchini) evolved from spontaneous crossing and gene exchange between pumpkins derived from northern North America and pumpkins derived from southern North America. Consistent with pictorial and narrative historical records, such crossing appears to have occurred in Renaissance Europe within the first decades of the European contact with North America. The Old World pumpkins are more closely related to the long-fruited, cultivar-groups than are the native North American pumpkins.