Genetic diversity and phenetic analysis in wheat (Triticum turgidum subsp. durum and Triticum aestivum subsp. aestivum) landraces based on SNP markers

Durum (Triticum turgidum L. subsp. durum (Desf.) Husn.) and common (Triticum aestivum L. subsp. aestivum) wheat landraces are mixtures of mostly homozygous genotypes characterized by broad adaptations to local environmental conditions. In this study, we estimated the genetic diversity in three old durum landraces ("San Pasquale", "Grano Ricco" and "Dauno III") and a common wheat landrace ("Bianchetta") by using phenotypic traits and Single Nucleotide Polymorphism (SNP) markers. Large phenotypic variation was found for yield components and grain-quality traits. The landraces "Grano Ricco" and "Dauno III" showed high grain yield per spike, kernel weight and grain protein content, suggesting that they could be a source of favorable alleles. SNP analysis showed a higher diversity within landraces in "Bianchetta" (9.5 %) and "Grano Ricco" (9.4 %) than in "Dauno III" (3.2 %) and "San Pasquale" (1.5 %). Comparing marker profiles, different haplotypes were found within each landrace indicating a genetic structure based on a mixture of genotypes. The phenetic analysis underlined four distinct clusters corresponding to the four wheat landraces examined. The phenetic tree showed that "Dauno III" and "San Pasquale" were strongly related with cultivars derived from Mediterranean durum landraces and genetically distant from "Grano Ricco" which clustered with 'Russello' and 'Timilia', two durum cultivars originated from southern Italy durum landraces.