Genetic diversity and population structure of cassava ethno-varieties grown in six municipalities in the state of Mato Grosso, Brazil
Cassava is one of the main energy foods for millions of people, and has a great diversity of ethno-varieties that have specific characteristics often not found in commercial varieties. These constitute a gene pool and therefore a genetic resource that should be conserved and preserved. In this context, the objective of our study was to evaluate the genetic diversity and population structure of ethno-varieties of cassava grown in six municipalities of the state of Mato Grosso, with the aim of characterization and conservation of the varieties found in this area. The study was carried out with 157 samples of cassava. For the molecular analyses, 15 fluorochrome-labeled SSR loci were used. Microsatellite markers amplified a total of 158 alleles. The polymorphism information content for each locus varied from 0.132 (SSRY126) to 0.838 (SSRY47), with a mean of 0.680. The expected and observed heterozygosity showed an average of between 0.717 and 0.688, for SSRY126 and SSRY47, respectively. The heterozygosity values observed were higher than those expected in five of the six populations, generating negative values of the fixation index (-0.070). Among the six populations, Alta Floresta and Cuiabá had the highest percentage of polymorphic loci (100%). The groupings obtained by UPGMA, Structure and PCoA among the six populations were concordant in allocating the individuals into two genetic groups. We found considerable genetic diversity among the samples, evidenced by the high values in the diversity indices. These high values are possibly related to the management of the fields and the exchange of propagative material among the farmers. Therefore, it is proposed that both populations be conserved since they have potential that could be used for genetic improvement of this essential crop.