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The 2009 ASHS Annual Conference

Genetic and Phenotypic Diversity within the USDA, ARS Capsicum baccatum Germplasm Collection

Tuesday, July 28, 2009
Illinois/Missouri/Meramec (Millennium Hotel St. Louis)
Elena Albrecht, KeyGene Inc., Rockville, MD
Dick Lensink, KeyGene N. V., Wageningen, Netherlands
Robert A. Saftner, USDA ARS, Damascus, MD
John Stommel, Genetic Improvement of Fruits and Vegetables Laboratory, USDA ARS, Beltsville, MD
The genus, Capsicum, is native to the tropics of Central and South America.  C. annuum is the most widely cultivated and economically important Capsicum species today.  Four additional domesticated Capsicum species include C. frutescens, C. chinense, C. baccatum and C. pubescens.  Approximately 25 additional wild Capsicum species are recognized but lack extensive study on their biology.  Utilizing morphological, chemical and sensory analysis and molecular markers, we have assessed intraspecific variation within 250 C. baccatum accessions obtained from the USDA, ARS, PGRCU.  A smaller number of C. annuum, C. chinense and C. frutescens accessions were similarly evaluated.  Domesticated types of C. baccatum are designated as C. baccatum var. pendulum and wild forms as C. baccatum var. baccatumC. baccatum var. pendulum is widely distributed in Central and South America whereas the wild form, C. baccatum, is centered in Bolivia and surrounding areas.  Similar to a number of other Capsicum species, C. baccatum pod types are diverse and fruit size, pigmentation, and flavor attributes exhibited considerable variability.  Fruit size ranged from very small round fruit (0.5 cm diameter) typical of C. baccatum var. baccatum to tapered elongate (12-15 cm length) fruit for C. baccatum var. pendulum.  Mature fruit pigmentation varied from yellow to orange to red.  Fruit flavor varied from mild to very pungent with presence or absence of unique aromatics and flavors.  Principle components analysis based upon marker diversity identified two major clusters containing C. baccatum var. pendulum and four smaller, additional clusters.  The latter consisted of a single cluster containing the majority of the C. baccatum var. baccatum accessions and three additional clusters represented by both forms of the species.  A tendency for clustering of accessions based upon their geographic origin was evident.  The results of the genetic diversity analysis will be discussed in relation to fruit phenotype attributes.