Resumen Capsicum pubescens es un ají picante cultivado, consumido en Latinoamérica como ingrediente distintivo y conocido como “locoto” o “rocoto”. Este taxón es un recurso sobresaliente por sus características de resistencia y tolerancia a estrés biótico/abiótico, y del fruto, que pueden ser introgresadas en programas de mejoramiento de C. annuum y especies relacionadas. En este estudio, se caracterizó detalladamente el complemento cromosómico de C. pubescens cv. “locoto” (2n = 24) a través de una combinación secuencial de herramientas citogenéticas convencionales y moleculares que incluyeron: tinción Ag-NOR, bandeos heterocromáticos fluorescentes C-DAPI, DAPI/AMD-CMA/DA, e hibridación in situ fluorescente (FISH) con sondas de genes de rRNA 5S y 18S-25S y diferentes regiones espaciadoras de la unidad ribosomal derivadas de Capsicum, y sonda telomérica. Los marcadores identificados se combinaron sistemáticamente con parámetros morfométricos del cariotipo - número, tamaño, centrómeros, satélites - para producir un mapa físico que permitió la identificación de varios caracteres de referencia en cada cromosoma individual. El mapa cromosómico de referencia de C. pubescens aquí presentado es el más completo hasta ahora desarrollado en Capsicum. Se prevé que este mapa cromosómico sirva de referencia para próximos proyectos de secuenciación y como punto de partida para asistir al mapeo genético de caracteres agronómicos importantes.
Abstract Capsicum pubescens is a cultivated hot chili pepper, consumed in Latin American cuisine as a distinctive ingredient, and popularly known as “locoto” or “rocoto”. This taxon is also an outstanding source of resistance to biotic and abiotic stresses as well as other valuable fruit traits for breeding of the worldwidely cultivated C. annuum and related species. In this study, the chromosome complement of C. pubescens cv. “locoto” (2n = 24) was deeply characterized through a sequential combination of conventional and molecular cytogenetics approaches comprising: Ag-NOR staining, heterochromatic fluorescent C-DAPI, DAPI/AMD-CMA/DA bandings, fluorescence in situ hybridization (FISH) of Capsicum-derived probes of the 5S and 18S-25S rRNA genes and different regions of spacers of the ribosomal unit, as well as telomeric probe. The markers identified were systematically combined with morphological karyotype parameters - number, size, centromeres, satellites - to produce a physical map which allowed the identification of several landmarks in each individual chromosome. The reference chromosomal map of C. pubescens here presented is the most comprehensively developed in Capsicum so far. It is envisioned that this chromosomal map will serve as a reference framework for the upcoming sequencing projects and as starting point to assist future genetic mapping of important agronomic traits.
Abstract Peanut (Arachis hypogaea L.) is a tetraploid species with an A and B genome, while the majority of wild Arachis species are diploid with distinct genomes. In pre-breeding programs, one way to introgress interesting wild genes into peanut is by producing amphidiploids. This study aimed at the hybridization between distinct amphidiploids and their characterization, to combine high crossability with peanut, observed in some amphidiploids, with high pest and disease resistances observed in others. These new hybrids were called complex hybrids. Four amphidiploids previously obtained were crossed at four different combinations, and the derived complex hybrids were crossed with four peanut cultivars. Morphological, reproductive, chromosome complement, molecular markers for hybrid identification, phytopatological, and entomological characterizations were performed on the complex hybrids. All cross combinations resulted in complex hybrids. One complete complement of each diploid progenitor was confirmed in each hybrid. Plants of six distinct hybrid combinations were obtained between the complex hybrids and peanut. Based on morphological characterization, differences among progenies from distinct cross combinations were observed. Complex hybrids were considered more resistant to all diseases and pests than peanut cultivars. The simultaneous introgression of genes from four wild Arachis species into peanut was possible through the development of complex hybrids.
The cytogenetic characterization of Arachis species is useful for assessing the genomes present in this genus, for establishing the relationship among their representatives and for understanding the variability in the available germplasm. In this study, we used fluorescence in situ hybridization (FISH) to examine the distribution patterns of heterochromatin and rDNA genes in 12 Brazilian accessions of five species of the taxonomic section Arachis. The heterochromatic pattern varied considerably among the species: complements with centromeric bands in all of the chromosomes (A. hoehnei) and complements completely devoid of heterochromatin (A. gregoryi, A. magna) were observed. The number of 45S rDNA loci ranged from two (A. gregoryi) to eight (A. glandulifera), while the number of 5S rDNA loci was more conserved and varied from two (in most species) to four (A. hoehnei). In some species one pair of 5S rDNA loci was observed adjacent to 45S rDNA loci. The chromosomal markers revealed polymorphism in the three species with more than one accession (A. gregoryi, A. magna and A. valida) that were tested. The previous genome assignment for each of the species studied was confirmed, except for A. hoehnei. The intraspecific variability observed here suggests that an exhaustive cytogenetic and taxonomic analysis is still needed for some Arachis species.
Saint Louis encephalitis virus (SLE) is a mosquito borne disease. Only a small proportion of cases progress to severe clinical forms. There have been few reports on HIV-infected patients and the relationship between immunodeficiency and the course of the disease remains unclear. Herein we describe two cases of SLE in HIV-1-infected patients in Buenos Aires city.