Caracterização, divergência genética e estrutura populacional de cultivares tradicionais de mandioca-de-mesa coletadas na Região Sul de Minas Gerais

Abstract

The first step of this work aimed to characterize the genetic divergence between 51 traditional cassava cultivars collected from four locations in the Southern region of Minas Gerais. Fifteen morphological characters analyzed from multicategoric variables and seven quantitative characters analyzed by the method of Average Euclidean distance which dissimilarity matrices and genetic similarity among accessions were generated was used. The Nearest Neighbor-UPGMA method was used as cluster analysis. For the analysis of qualitative morphological descriptors was the formation of six distinct groups, with the BGM 674, BGM 686 and BGM 690 hits were the most divergent and combinations between BGM 640 x BGM 690, BGM 647 x BGM 690, BGM 675 x BGM BGM 690, BGM 678 x BGM 690 and BGM 680 x BGM 690 are considered as the most promising for a future breeding program. For quantitative descriptors was the formation of seven distinct groups, and the BGM 655, BGM 640, BGM 660 and BGM 690 hits were the most divergent, with the most promising combinations indicated in a future breeding program are between parental BGM 675 x BGM 690 and BGM 690 x BGM BGM 660. In the second step of this work was the application of 20 microsatellite markers. All were considered polymorphic loci analyzed with an average of 3,4 alleles per locus. The average value of PIC indicated that the markers were mostly mildly informative, and the loci with higher PIC were 127 GA, 21 SSRY, SSRY 28 and GA 57 with values of 0,6763; 0,6273; 0,5456 and 0,5236 respectively. As it relates to heterozygosity, the mean value of 0,6487 was considered high and SSRY 51, SSRY 19, GA 140 and GA 131 loci were those with the highest value, equal to 1.0. With respect to genetic diversity, the average was 0,4810 ranging from 0,0968 to 0,7270 for GA 136 and GA 127 Among the most divergent accessions, stood 684 BGM, BGM 655, 647 BGM, BGM 660, which accesses considered viable for a future breeding program. Population structure proved to be quite heterogeneous with four groups based on the methodologies of CS Chord genetic distance and the probabilistic method. Thus, the 20 primers evaluated showed satisfactory results considering the genetic diversity and population structure present in traditional cassava cultivars collected from the Southern Region of Minas Gerais State.