Molecular Diversity within a Mediterranean and European Panel of Tetraploid Wheat (T. turgidum subsp.) Landraces and Modern Germplasm Inferred Using a High-Density SNP Array

High-density single-nucleotide polymorphism (SNP) molecular markers are widely used to assess the genetic variability of plant varieties and cultivars, which is nowadays recognized as an important source of well-adapted alleles for environmental stresses. In our study, the genetic diversity and population genetic structure of a collection of 265 accessions of eight tetraploid Triticum turgidum L. subspecies were investigated using 35,143 SNPs screened with a 35K Axiom (R) array. The neighbor-joining algorithm, discriminant analysis of principal components (DAPC), and the Bayesian model-based clustering algorithm implemented in STRUCTURE software revealed clusters in accordance with the taxonomic classification, reflecting the evolutionary history of the Triticum turgidum L. subspecies and the phylogenetic relationships among them. Based on these results, a clear picture of the population structure within a collection of tetraploid wheats is given herein. Moreover, the genetic potential of landraces and wild relatives for the research of specific traits of interest is highlighted. This research provides a great contribution to future phenotyping and crossing activities. In particular, the recombination efficiency and gene selection programs aimed at developing durum wheat composite cross populations that are adapted to Mediterranean conditions could be improved.