Transferability of microsatellite markers of Capsicum annuum L. to C. frutescens L. and C. chinense Jacq.

In order to support further genetic, diversity, and phylogeny studies of Capsicum species, the transferability of a Capsicum annuum L. simple sequence repeat (SSR) microsatellite set was analyzed for C. frutescens L. ("malagueta" and "tabasco" peppers) and C. chinense Jacq. (smell peppers, among other types). A total of 185 SSR primers were evaluated in 12 accessions from 115 C. frutescens L. and 480 C. chinense Jacq, representing different types within each species. Transferability to C. frutescens L. and C. chinense Jacq. occurred for 116 primers (62.7%). Nineteen (16.37%) were polymorphic in C. frutescens L. and 36 (31.03%) in C. chinense Jacq., 17 of which were coincident and could be used to analyze samples obtained for the 2 species. Among these primers, CA49 showed a different amplitude range of alleles between the 2 species (130-132 base pairs for C. frutescens L. and 120-128 base pairs for C. chinense Jacq.), and could differentiate the species. A total of 55 alleles were identified among the 19 polymorphic SSR loci among accessions of C. frutescens L., with the number of alleles per locus ranging from 2 to 5, a mean of 2.89, and the polymorphic information content ranging from 0.30 to 0.65. The number of alleles identified in C. chinense Jacq. was 119, ranging from 2 to 5 alleles per locus, an average of 3.30, and polymorphic information content from 0.19 to 0.68. The C. annuum L. SSR primers were most often transfer-able and polymorphic for C. frutescens L. and C. chinense Jacq., and we present a set of SSR for each species.

Carvalho SI ，Ragassi CF ，Oliveira IB ，Amaral ZP ，Reifschneider FJ ，Faleiro FG ，Buso GS ... -  《Genetics and Molecular Research》

Novel and highly informative Capsicum SSR markers and their cross-species transferability.

This study was undertaken primarily to develop new simple sequence repeat (SSR) markers for Capsicum. As part of this project aimed at broadening the use of molecular tools in Capsicum breeding, two genomic libraries enriched for AG/TC repeat sequences were constructed for Capsicum annuum. A total of 475 DNA clones were sequenced from both libraries and 144 SSR markers were tested on cultivated and wild species of Capsicum. Forty-five SSR markers were randomly selected to genotype a panel of 48 accessions of the Capsicum germplasm bank. The number of alleles per locus ranged from 2 to 11, with an average of 6 alleles. The polymorphism information content was on average 0.60, ranging from 0.20 to 0.83. The cross-species transferability to seven cultivated and wild Capsicum species was tested with a set of 91 SSR markers. We found that a high proportion of the loci produced amplicons in all species tested. C. frutescens had the highest number of transferable markers, whereas the wild species had the lowest. Our results indicate that the new markers can be readily used in genetic analyses of Capsicum.

Buso GS ，Reis AM ，Amaral ZP ，Ferreira ME ... -  《Genetics and Molecular Research》

New insights into Capsicum spp relatedness and the diversification process of Capsicum annuum in Spain.

The successful exploitation of germplasm banks, harbouring plant genetic resources indispensable for plant breeding, will depend on our ability to characterize their genetic diversity. The Vegetable Germplasm Bank of Zaragoza (BGHZ) (Spain) holds an important Capsicum annuum collection, where most of the Spanish pepper variability is represented, as well as several accessions of other domesticated and non-domesticated Capsicum spp from all over the five continents. In the present work, a total of 51 C. annuum landraces (mainly from Spain) and 51 accessions from nine Capsicum species maintained at the BGHZ were evaluated using 39 microsatellite (SSR) markers spanning the whole genome. The 39 polymorphic markers allowed the detection of 381 alleles, with an average of 9.8 alleles per locus. A sizeable proportion of alleles (41.2%) were recorded as specific alleles and the majority of these were present at very low frequencies (rare alleles). Multivariate and model-based analyses partitioned the collection in seven clusters comprising the ten different Capsicum spp analysed: C. annuum, C. chinense, C. frutescens, C. pubescens, C. bacatum, C. chacoense and C. eximium. The data clearly showed the close relationships between C. chinense and C. frutescens. C. cardenasii and C. eximium were indistinguishable as a single, morphologically variable species. Moreover, C. chacoense was placed between C. baccatum and C. pubescens complexes. The C. annuum group was structured into three main clusters, mostly according to the pepper fruit shape, size and potential pungency. Results suggest that the diversification of C. annuum in Spain may occur from a rather limited gene pool, still represented by few landraces with ancestral traits. This ancient population would suffer from local selection at the distinct geographical regions of Spain, giving way to pungent and elongated fruited peppers in the South and Center, while sweet blocky and triangular types in Northern Spain.

González-Pérez S ，Garcés-Claver A ，Mallor C ，Sáenz de Miera LE ，Fayos O ，Pomar F ，Merino F ，Silvar C ... -  《PLoS One》

Morphological and genetic relationships between wild and domesticated forms of peppers (Capsicum frutescens L. and C. chinense Jacquin).

Capsicum chinense and C. frutescens peppers are part of the Brazilian biodiversity, and the Amazon basin is the area of greatest diversity for them, especially for that former species. Nevertheless, little is known about their evolutionary history. Aiming to identify genotypes with wild and domesticated characteristics, 30 accessions of the germplasm bank of Embrapa were characterized using morphological descriptors and ISSR molecular markers. Of the 72 primers tested, 42% showed amplification and produced 136 amplicons with some of the primers, namely i7Pv and i57Zm, allowing the identification of each species. ISSR also revealed polymorphisms within a species, especially between domesticated and wild forms. Four wild accessions collected in the Amazon region (CNPH 4315, CNPH 4372, CNPH 4337 and CNPH 4325B) popularly known as "olho-de-peixe" or "olho-de periquito" were molecularly classified as C. chinense and showed fruit with similar characteristics as the wild species: upright position, rounded to campanulate shape, small size (1.0 cm long and 0.8 cm wide), average weight of 0.2 g, dark-red color when ripe, easy detachment of calyx and presence of calyx annular constriction (discriminative of C. chinense). The wild form CNPH 4353 known as "malaguetinha" was morphologically and molecularly classified as C. frutescens, demonstrating a more preserved morphology in C. frutescens than in C. chinense. A significant correlation was found between morphological and molecular characterization, and the combination of the two analyses was effective in identifying and classifying the wild forms and contributing to evolutionary studies in the genus.

Carvalho SI ，Ragassi CF ，Bianchetti LB ，Reifschneider FJ ，Buso GS ，Faleiro FG ... -  《Genetics and Molecular Research》

Genetic variability of a Brazilian Capsicum frutescens germplasm collection using morphological characteristics and SSR markers.

Characterization studies provide essential information for the conservation and use of germplasm in plant breeding programs. In this study, 103 Capsicum frutescens L. accessions from the Active Germplasm Bank of Embrapa Hortaliças, representative of all five Brazilian geographic regions, were characterized based on morphological characteristics and microsatellite (or simple sequence repeat - SSR) molecular markers. Morphological characterization was carried out using 57 descriptors, and molecular characterization was based on 239 alleles from 24 microsatellite loci. From the estimates of genetic distances among accessions, based on molecular characterization, a cluster analysis was carried out, and a dendrogram was established. Correlations between morphological and molecular variables were also estimated. Twelve morphological descriptors were monomorphic for the set of C. frutescens accessions, and those with the highest degree of polymorphism were stem length (14.0 to 62.0 cm), stem diameter (1.0 to 4.2 cm), days to flowering (90 to 129), days to fruiting (100 to 140), fruit weight (0.1 to 1.4 g), fruit length (0.6 to 4.6 cm), and fruit wall thickness (0.25 to 1.5 mm). The polymorphism information content for the SSR loci varied from 0.36 (EPMS 417) to 0.75 (CA49), with an overall mean of 0.57. The correlation value between morphological and molecular characterization data was 0.6604, which was statistically significant. Fourteen accessions were described as belonging to the morphological type tabasco, 85 were described as malagueta, and four were malaguetinha, a morphological type confirmed in this study. The typical morphological pattern of malagueta was described. Six similarity groups were established for C. frutescens based on the dendrogram and are discussed individually. The genetic variability analyzed in the study highlights the importance of characterizing genetic resources available for the development of new C. frutescens cultivars with the potential for various niche markets.

Carvalho SIC ，Bianchetti LB ，Ragassi CF ，Ribeiro CSC ，Reifschneider FJB ，Buso GSC ，Faleiro FG ... -  《Genetics and Molecular Research》