Genetic Variation in Tobacco Germplasm Identified By DArT-Seq Markers

Tobacco (Nicotiana tabacum L.) is one of the most important commercial non-food crop in the world. As in other cultures, genetic improvement concerning it is performed using a narrow genetic basis. Among other reasons, the lack of knowledge about the genetic diversity of tobacco germplasm constitutes a limitation to its use in breeding programs. For this reason, the study of the genetic diversity is the first step to a better use of this germplasm. Thus, the objectives of this study were to characterize the genetic diversity and understand the structure of 87 accesses from 9 varietal groups. The characterization was made using DArT-seq technique, largely unexplored in tobacco. A filtering was held considered markers with low quantity of missing data and high reproducibility, resulting in 424 SNPs markers of high quality. The genetic diversity average, quantified by the expected heterozygosity, was low for all varietal groups (He=0,027). Cluster analyzes using the Unweighted Pair Group Method with arithmetic mean (UPGMA) showed that the accesses could be grouped into two principal clusters, while using Discriminant Analysis of Principal Components (DAPC) analyzes found 5 clusters. Analysis of molecular variance (AMOVA) showed that the genetic variation was found mainly within varietal groups (77.63%), but variance among varietal groups was only 22.37%. The results showed that through the analysis of DArT-seq markers was not verified the structure of 9 clusters, corresponding to the 9 varietal groups, whereas genotypes of different groups share alleles.