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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Genetic Improvement for Fruits & Vegetables Laboratory » Research » Publications at this Location » Publication #245952
Title: Genetic diversity and population structure of Capsicum baccatum genetic resources

Author
item ALBRECHT, ELENA - Keygene, Inc
item Saftner, Robert
item Stommel, John
item Zhang, Dapeng

Submitted to: Genetic Resources and Crop Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/12/2011
Publication Date: 5/27/2011
Citation: Albrecht, E., Saftner, R.A., Stommel, J.R., Zhang, D. 2011. Genetic diversity and population structure of Capsicum baccatum genetic resources. Genetic Resources and Crop Evolution. 59:517-538.

Interpretive Summary: Exotic peppers such as the aji or Peruvian hot pepper are a valuable source of new genes that could be used to improve fruit quality and disease resistance in sweet bell or hot chile pepper. We used molecular genetics to study variation among genes in these exotic peppers. We can use the differences we found in these exotic peppers to breed peppers with improved eating quality and resistance to pepper diseases. This new knowledge will be valuable for plant explorers who collect exotic plants and for plant breeders working to develop new peppers.

Technical Abstract: Capsicum baccatum is one of five cultivated pepper species which, despite its morphological and ecological variability, has been underexploited for germplasm improvement. Utilizing a broad spectrum of C. baccatum germplasm, we describe the species’ molecular diversity and population structure. Knowledge of the genetic diversity in germplasm resources is essential to identifying accessions for crop improvement and guides the development of efficient in situ and ex situ conservation programs. Variability observed in wild C. baccatum accessions based on AMOVA, genetic distance and marker diversity was greater than that observed in domesticated forms of the species. Average similarities were 63% among wild types and 73% among cultivated forms. AFLP marker profiles suggested that wild accessions have incurred greater levels of inbreeding than cultivated forms, an indication that wild populations may be declining in their native habitats. Genetic relatedness within C. baccatum was largely a function of type (wild vs. domesticated) as well as geographic origin. Wild types exhibited marked isolation by distance relative to cultivated forms, occupying basal clades in UPGMA derived dendrograms. Independent of basal clades, C. baccatum accessions occupied two major groups comprised of accessions from the species western and eastern South American distribution. These genetic groups suggested the evolution of two lineages, followed by an extended period of lineage differentiation. A survey of genetic diversity across species occupying the baccatum and annuum complexes supported independent lineages for the two complexes. The genetic distance between C. baccatum var. praetermissum and related C. baccatum accessions was as large as or larger than that among species of the annuum complex, suggesting that species-status should be considered for C. baccatum var. praetermissum. Nesting of C. baccatum var. umbilicatum deeply within C. baccatum var. pendulum does not support taxonomic distinction of this variety.