Diversity and Genetic Structure of a Collection of Spanish Durum Wheat Landraces

Knowledge of the genetic structure of germplasm collections is crucial for conservation and efficient use of genetic resources. This study assessed the diversity and genetic structure of a collection of landraces of Spanish durum wheat (Triticum turgidum L.) using several marker systems and correlated the diversity and agromorphological traits with geographic and climatic features. Analyzed genotypes were separated into nine populations, with moderate to great genetic divergence among them. The three subspecies dicoccon, turgidum, and durum present in the collection largely determined the clustering of the populations. Genotype variation was lower in dicoccon and turgidum than in durum. Genetic differentiation by the agroecological zone of origin was greater in dicoccon and turgidum than in durum. Diversity arrays technology markers revealed two geographic substructures, east-west for dicoccon and northeast-southwest for turgidum. The ssp. durum had a more complex structure, consisting of seven populations with high intrapopulation variation. Diversity arrays technology markers allowed the detection of subgroups within some populations, with agromorphological and gliadin differences, and distinct agroecological zones of origin. Two different phylogenetic groups were detected, revealing that some durum accessions were more related to ssp. turgidum from northern Spain while others seem to be more related to durum wheats from North Africa.