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Robert Lawrence Jarret and Terry Berke

Mature fruit of 330 accessions of Capsicum chinense Jacq. from the USDA/ARS Capsicum germplasm collection were characterized for fruit length, width, weight, and color. Mean fruit length was determined to be 47 mm with a range from 7.9 mm to 113.7 mm. Mean fruit width was 21.17 mm with a range of 6.18 mm to 40.0 mm. Mean fruit weight was 6.31 g with a range of 0.18 g to 22.7 g. Distributions of all characteristics were positively skewed. Distributions of fruit length, fruit weight, and fruit length/width failed the Kolmogorov-Smirnov test for normality. The distribution for fruit width was normal. Ninety-two percent of the accessions examined were elongate. Mature fruit colors included red, orange, yellow, brown (chocolate), and cream. The germplasm collection contained primarily pendent larger-fruited cultivated forms of the species, but also contained upright small-fruited primitive and semipendent transitional forms. These data define the variability for mature fruit characteristics within this germplasm collection and provide a baseline against which future introductions/acquisitions can be compared. Additional sampling of the gene pool might be expected to substantially enhance the genetic variability within the primitive forms of this species.

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Julie Villand, Terry Berke, Liwayway Engle and James Nienhuis

Significant effort has been made in the collection of Capsicum germplasm throughout the world for maintenance by genebanks. The largest Capsicum germplasm collection is held by the Asian Vegetable Research and Development Center (AVRDC), consisting of 6844 accessions and eight species. The paradox of any germplasm collection is that, as the number of accessions and the probability of preserving genetic variability increases, the ability of users to efficiently utilize this resource decreases. Genetic variation can be quantified using RAPD molecular marker allele frequency and allelic variation to understand the genetic structure and variation within and among populations. The comprehensive Capsicum collection held at the AVRDC provides an opportunity to sample a range of germplasm representative of the variability that exists in available Capsicum germplasm. Accessions were sampled from the AVRDC collection to represent the range of genetic variation available in Capsicum 1) based on cluster analysis using morphological traits among 1500 accessions and 2) based on pedigree information from the Capsicum breeding program. Our objectives include understanding the structure and magnitude of genetic diversity among these AVRDC accessions and comparing the genetic diversity within sub-populations of these accessions. RAPD fingerprints of these accessions were collected using markers dispersed over numerous linkage groups based on a genetic map we have constructed. RAPD band frequencies and RAPD band diversity were used to test differences among and within sub-populations. The understanding of the distribution of genetic variation among and within these sub-populations will be useful for prioritizing collection, conservation, and sampling of these genetic resources.

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Robert L. Jarret, Gloria E. Barboza, Fabiane Rabelo da Costa Batista, Terry Berke, Yu-Yu Chou, Amanda Hulse-Kemp, Neftali Ochoa-Alejo, Pasquale Tripodi, Aniko Veres, Carolina Carrizo Garcia, Gabor Csillery, Yung-Kuang Huang, Erzsebet Kiss, Zsofia Kovacs, Mihaly Kondrak, Magda Lisette Arce-Rodriguez, Marisel A. Scaldaferro and Antal Szoke

Pepper (Capsicum L.) is a major vegetable and spice crop worldwide. Global production of both fresh and dried fruit continues to increase steadily in terms of area harvested and yield. Various topics are addressed in this review, including recent additions to and clarification of Capsicum taxonomy, genetic resources of Capsicum, cytogenetic studies, the current status of our understanding of the mechanisms affecting the biosynthesis of capsaicinoids, the use of gene mutations to elucidate carotenoid biosynthetic pathways and their regulation, and recent advances in whole-genome sequencing and assembly.