RESUMO
Evolutionary studies in plant and animal breeding are aimed at understanding the structure and organization of genetic variations of species. We have identified and characterized a genomic sequence in Phaseolus vulgaris of 1,200 bp (PvSHP1) that is homologous to SHATTERPROOF-1 (SHP1), a gene involved in control of fruit shattering in Arabidopsis thaliana. The PvSHP1 fragment was mapped to chromosome Pv06 in P. vulgaris and is linked to the flower and seed color gene V. Amplification of the PvSHP1 sequence from the most agronomically important legume species showed a high degree of interspecies diversity in the introns within the Phaseoleae, while the coding region was conserved across distant taxa. Sequencing of the PvSHP1 sequence in a sample of 91 wild and domesticated genotypes that span the geographic distribution of this species in the centers of origin showed that PvSHP1 is highly polymorphic and, therefore, particularly useful to further investigate the origin and domestication history of P. vulgaris. Our data confirm the gene pool structure seen in P. vulgaris along with independent domestication processes in the Andes and Mesoamerica; they provide additional evidence for a single domestication event in Mesoamerica. Moreover, our results support the Mesoamerican origin of this species. Finally, we have developed three indel-spanning markers that will be very useful for bean germplasm characterization, and particularly to trace the distribution of the domesticated Andean and Mesoamerican gene pools.
Assuntos
Produtos Agrícolas/genética , Genes de Plantas/genética , Variação Genética , Nucleotídeos/genética , Phaseolus/genética , Pareamento de Bases/genética , Sequência de Bases , América Central , Mapeamento Cromossômico , DNA Intergênico/genética , Ligação Genética , Marcadores Genéticos , Genética Populacional , Mutação INDEL/genética , Dados de Sequência Molecular , Filogeografia , Dinâmica Populacional , Característica Quantitativa Herdável , Recombinação Genética/genética , América do Sul , Especificidade da EspécieRESUMO
Lack of introgression or divergent selection may be responsible for the maintenance of phenotypic differences between sympatric populations of crops and their wild progenitors. To distinguish between these hypotheses, amplified fragment length polymorphism markers were located on a molecular linkage map of Phaseolus vulgaris relative to genes for the domestication syndrome and other traits. Diversity for these same markers was then analyzed in two samples of wild and domesticated populations from Mesoamerica. Differentiation between wild and domesticated populations was significantly higher in parapatric and allopatric populations compared to sympatric populations. It was also significantly higher near genes for domestication compared to those away from these genes. Concurrently, the differences in genetic diversity between wild and domesticated populations were strongest around such genes. These data suggest that selection in the presence of introgression appears to be a major evolutionary factor maintaining the identity of wild and domesticated populations in sympatric situations. Furthermore, alleles from domesticated populations appear to have displaced alleles in sympatric wild populations, thus leading to a reduction in genetic diversity in such populations. These results also provide a possible experimental framework for assessing the long-term risk of transgene escape and the targeting of transgenes inside the genome to minimize the survival of these transgenes into wild populations following introduction by gene flow.
Assuntos
Mapeamento Cromossômico , Produtos Agrícolas/genética , Variação Genética , Genética Populacional , Genoma de Planta/genética , Phaseolus/genética , Primers do DNA , México , Técnicas de Amplificação de Ácido Nucleico , Polimorfismo de Fragmento de RestriçãoRESUMO
Using amplified fragment length polymorphisms (AFLPs), we analyzed the genetic structure of wild and domesticated common bean (Phaseolus vulgaris L.) from Mesoamerica at different geographical levels to test the hypothesis of asymmetric gene flow and investigate the origin of weedy populations. We showed both by phenetic and admixture population analyses that gene flow is about three- to four-fold higher from domesticated to wild populations than in the reverse direction. This result, combined with other work, points to a displacement of genetic diversity in wild populations due to gene flow from the domesticated populations. The weedy populations appear to be genetically intermediate between domesticated and wild populations, suggesting that they originated by hybridization between wild and domesticated types rather than by escape from cultivation. In addition, the domesticated bean races were genetically similar confirming a single domestication event for the Mesoamerican gene pool. Finally, the genetic diversity of the domesticated bean population showed a lower level of geographic structure in comparison to that of the wild populations.
Assuntos
Fabaceae/genética , Filogenia , América Central , Pool Gênico , Marcadores Genéticos , Variação Genética , Genética Populacional , Geografia , México , Técnicas de Amplificação de Ácido Nucleico , Polimorfismo GenéticoRESUMO
Os autores apresentam um caso de estenose aortica supravalvar associada a anomalia facial e a retardo mental, caracterizando a sindrome de Williams-Beuren. Sao abordados os aspectos etiologicos, o quadro clinico, os metodos de exames complementares de diagnostico e o tratamento cirurgico