Establishment of Capsicum frutescens core collections based on morphological and molecular descriptors and on virus incidence
Malagueta (Capsicum frutescens) is one of the most widely consumed and cultivated Brazilian hot peppers. It is an important crop for smallholder farmers throughout the country. Currently, the demand for new hot pepper cultivars is increasing. A germplasm collection of C. frutescens is maintained at Embrapa Vegetables, Brasilia, Brazil, the branch for vegetable crops of the Brazilian Agricultural Research Corporation (EMBRAPA). This is considered to be the main collection representing the variability of this species in the country. Four core collections of 13 accessions each were established through 1) random selection, 2) selection based on morphological and 3)SSR similarity groups and 4) selection based on SSR similarity groups associated with virus incidence. Characterizing the original germplasm collection (103 accessions) through 57 morphological characters, 239 alleles of 24 microsatellite (SSR) loci and incidence of six virus species provided the information used for selecting the accessions. Discriminating C. chinense and C. frutescens species proved to be inaccurate when relying only on morphological characterization for 5% of the accessions, whereas molecular characterization was decisive for the species identification of all accessions. The SSR allelic variability within each core collection was compared with the full C. frutescens collection. Selection based on SSR grouping associated with data on viruses incidence provided the highest allelic representativeness among the four strategies (77% of the allelic variability present in the full collection), in addition to satisfactorily representing the Brazilian geographic diversity. The core collection based on morphological characters was also highly representative of the allelic variability (73%) in the original full collection.