Desenvolvimento, caracterizaÃÃo e estimativas de erros de genotipagem de locos microssatÃlites de tabebuia Ãurea (bignoniaceae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Tabebuia aurea (Bignoniaceae) is a widespread Brazilian Cerrado tree species, pollinated by large-sized bees and dispersed by wind. It is a remarkably important species for the local population of the Brazilian Cerrado, for timber logging and for homemade recipes for medical purposes. The fragmentation of the âCerradoâ vegetation in Brazil and the higher frequency of fire caused by agricultural practices have been affecting recruitment and ultimately population size and dynamics of T. aurea and other Cerrado tree species. Microsatellite markers have increasingly been used as a very effective tool for understanding population genetic structure, gene flow, parentage, population viability and, ultimately, to quantify the effects of habitat fragmentation and to guide conservation strategies. In this work we present the development of microsatellite markers to study population genetic structure of T. aurea, and generate useful information for the species conservation. These markers were developed using a genomic library enrichment procedure for AG/TC. Additionally, the markers were tested for four other species of the same genus. From the 271 positive colonies sequenced, 31 were useful sequences from which primer pairs were designed. Twenty one primers amplified using a single PCR protocol and generated clearly interpretable products at 56oC of annealing. These loci were characterized using 36 individuals of T. aurea. Number of alleles per locus, expected and observed heterozygosity ranged from 09 to 26, 0.808 to 0.955 and 0,466 to 0,944, respectively. The low combined probability of genetic identity (1.03x10â37) and high probability of paternity exclusion (0.9889) showed that multilocus genotypes are likely to be unique and will allow detailed parentage studies in natural populations of T. aurea. At least ten loci amplified for all the species, showing a high percentage of transferability for the four species of the same genus studied. Additionally, an automated system for high throughput genotyping was developed for T.aurea using the Genotyper program (Applied Biosystems). This method was compared to silver nitrate detection. The results showed that size calling based on a visual comparison with a 10pb DNA ladder standard in a silver stained polyacrylamide gel is more prone to genotyping errors than fluorescence-based automated genotyping. Additionally, the method of genotyping error analysis implemented in the software Micro-Checker overestimated the frequency of null alleles, compared to estimation based on the segregation of 12 microsatellite loci.

ASSUNTO(S)

null alleles genetica vegetal microssatÃlites microsatellites erros de genotipagem transferibilidade alelo nulos tabebuia aurea cerrados; genÃtica vegetal bignoniaceae genotying error cerrado

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