Characterization of a pepper collection (Capsicum frutescens L.) from Brazil.

Germplasm banks are essential as sources of genetic variability for plant breeding programs. To characterize a Brazilian Capsicum frutescens collection, 21 malagueta and 5 Tabasco hot pepper accessions were evaluated under field and greenhouse conditions regarding morphological and molecular traits, as well as resistance to viruses. Morphological characterization was performed using 53 IPGRI (International Plant Genetic Resources Institute) descriptors, 15 vegetative, 13 inflorescence, 22 fruit, and 3 seed. Molecular characterization was carried out with 60 polymorphic markers from 29 RAPD primers. The incidence of major viruses infecting Capsicum spp, Tomato spotted wilt virus (TSWV), Groundnut ringspot virus (GRSV), Potato virus Y (PVY), Pepper yellow mosaic virus (PepYMV), Pepper mild mottle virus (PMMoV), and Cucumber mosaic virus (CMV) was evaluated by ELISA. Based on the average genetic distance among genotypes, six groups were defined for the 53 IPGRI descriptors. When considering only 11 quantitative traits (five vegetative and six fruit), six groups were also determined, and the traits plant canopy width (56.05%) and days to fruiting (25.07%) most explained the genetic diversity among genotypes. Molecular analysis defined five groups of accessions with partial correspondence to the morphological characterization data. The incidence of viruses in field-grown plants varied among genotypes and according to virus species, from 5.6% (GRSV; CNPH 3286) to 100% (PMMoV; CNPH2871), and indicated some accessions as potential sources of virus resistance. These results demonstrate the genetic variability within the group of 26 hot pepper accessions, as well as virus-resistant genotypes that can be used in breeding programs.

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.

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.

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.

Gene flow from transgenic to nontransgenic soybean plants in the Cerrado region of Brazil.

Evaluation of transgenic crops under field conditions is a fundamental step for the production of genetically engineered varieties. In order to determine if there is pollen dispersal from transgenic to nontransgenic soybean plants, a field release experiment was conducted in the Cerrado region of Brazil. Nontransgenic plants were cultivated in plots surrounding Roundup Ready transgenic plants carrying the cp4 epsps gene, which confers herbicide tolerance against glyphosate herbicide, and pollen dispersal was evaluated by checking for the dominant gene. The percentage of cross-pollination was calculated as a fraction of herbicide-tolerant and -nontolerant plants. The greatest amount of transgenic pollen dispersion was observed in the first row, located at one meter from the central (transgenic) plot, with a 0.52% average frequency. The frequency of pollen dispersion decreased to 0.12% in row 2, reaching 0% when the plants were up to 10 m distance from the central plot. Under these conditions pollen flow was higher for a short distance. This fact suggests that the management necessary to avoid cross-pollination from transgenic to nontransgenic plants in the seed production fields should be similar to the procedures currently utilized to produce commercial seeds.

Gene flow from transgenic to nontransgenic soybean plants in the Cerrado region of Brazil

Evaluation of transgenic crops under field conditions is a fundamental step for the production of genetically engineered varieties. In order to determine if there is pollen dispersal from transgenic to nontransgenic soybean plants, a field release experiment was conducted in the Cerrado region of Brazil. Nontransgenic plants were cultivated in plots surrounding Roundup Ready transgenic plants carrying the cp4 epsps gene, which confers herbicide tolerance against glyphosate herbicide, and pollen dispersal was evaluated by checking for the dominant gene. The percentage of cross-pollination was calculated as a fraction of herbicide-tolerant and -nontolerant plants. The greatest amount of transgenic pollen dispersion was observed in the first row, located at one meter from the central (transgenic) plot, with a 0.52% average frequency. The frequency of pollen dispersion decreased to 0.12% in row 2, reaching 0% when the plants were up to 10 m distance from the central plot. Under these conditions pollen flow was higher for a short distance. This fact suggests that the management necessary to avoid cross-pollination from transgenic to nontransgenic plants in the seed production fields should be similar to the procedures currently utilized to produce commercial seeds.