Submitted to: BioMed Central (BMC) Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2012
Publication Date: 8/6/2012
Publication URL: http://handle.nal.usda.gov/10113/58548
Citation: Albrecht, E., Zhang, D., Saftner, R.A., Stommel, J.R. 2012. Genetic diversity in Capsicum baccatum is significantly influenced by its ecogeographical distribution. BioMed Central (BMC) Genetics. 13:89. Interpretive Summary: The exotic pepper species Capsicum baccatum, also known as the aji or Peruvian hot pepper, is a valuable source of new genes that could be used to improve fruit quality and disease resistance in sweet bell or hot chile pepper. However, relatively little research has been conducted to characterize the species, thus limiting its use in breeding improved pepper varieties. Together with DNA fingerprints, we evaluated variation in fruit and plant morphology of plants collected across the species native range in South America and evaluated these characters in combination with the unique geology, climate and ecology at different sites where plants originated. Our results document a high level of genetic and morphological diversity within Capsicum baccatum and distribution of the species over wide geographic areas in South America where it is adapted to divergent ecological conditions. The results will assist scientists in selecting appropriate plants to enter into breeding programs and maximize progress in crop improvement. The results will also promote conservation of the species by providing a framework for efficient management of pepper collections and guidance for future plant acquisitions.
Technical Abstract: The structure of genetic diversity in a plant germplasm collection is significantly influenced by its ecogeographical distribution. Improved understanding of the combined effects of geology, ecology and human intervention is essential for efficient conservation and use of plant germplasm. In the present study, a combined diversity analysis was carried out on the USDA-ARS Capsicum baccatum germplasm collection using data from GIS, morphological traits and DNA fingerprints. The results demonstrate that the C. baccatum collection covers wide geographic areas and is adapted to divergent ecological conditions in South America. A high level of morphological diversity was evident in the collection, with fruit weight the key variable. The fruit weight distribution pattern was compatible to AFLP based clustering analysis for the collection. A significant spatial structure was observed in the C. baccatum gene pool, specifically at a local scale. Division of the domesticated germplasm into two major regional groups (Western and Eastern) was further supported by the pattern of spatial population structure. The results further define the organization of the C. baccatum gene pool and thus will enhance the efficiency of conservation and utilization of this cultivated Capsicum species