Análise da variabilidade genética de populações do banco de germoplasma de camu-camu (myrciaria dubia (h.b.k.) mcvaugh) utilizando marcadores microssatélites

Abstract

The camu-camu (Myrciaria dubia (HBK) McVaugh) is an Amazonian endemic shrub that develops in periodically flooded areas. Its fruits have the highest content of ascorbic acid known and is therefore used in the manufacture of various products. The Instituto Nacional de Pesquisas da Amazônia maintains an active germplasm collection (BAG) of camu-camu with plants grown from seeds collected in several localities. The use of microsatellite molecular markers allows the characterization of acessions in the BAG, showing the existing structure and genetic variability, which provides guidance in the selection of matrices and the maintenance of genetic diversity. Thus, were developed 12 microsatellite primers from a genomic enriched library, nine polymorphic. The number of alleles per locus ranged from 3 to 10, with a mean of 6.89 alleles per locus. The observed heterozygosity (HO) had an average of 0.531 and the expected heterozygosity (He) had an average of 0.679. The discrimination power values DL were higher than 0.75 in six loci, close to this value at a locus. The D values were higher in seven loci, wich are considered more informative and used for analysis of populations. To help programs for improvement, were evaluated diversity, structure and genetic relationships of 17 populations of the INPA active germplasm collection. Seven microsatellite loci contained a total of 135 alleles, with an average of 19.3 alleles per locus. The results of the parameters of genetic diversity suggest the existence of an excess of homozygotes. The analysis of molecular variance (AMOVA) showed that 79.39% of the total genetic variation was found within the accessions and 20.61% among populations, demonstrating the existence of genetic structuring. There was no correlation between genetic and geographical distances (r = 0.23) indicating that populations are not structured in space. Such information can support the organization of the BAG and the direction of crosses, defining the access/ populations genetically divergent.