Whole genome scan reveals genetic diversity of Tunisian durum wheat germplasm

Durum wheat landraces can be a useful resource to restore the genetic diversity of modern cultivars. Tunisia has several accessions kept in the National Genebank which are still unexplored. In this work, a panel of Tunisian durum landraces and modern cultivars were investigated using morphological descriptors and the Illumina iSelect 15K wheat SNP array to study the genetic relationships and discover divergent loci involved in Tunisian breeding history. A panel of 5,555 polymorphic SNPs was used to investigate the population structure, which identified wo landrace groups and one group of cultivars; this genetic structure was validated by AMOVA and diversity indices. A total of 529 SNP loci were found divergent between landraces and modern cultivars, and candidate genes related to plant and spike architecture were identified. Divergent genes related to grain composition and biotic stress (leucine-reach repeats proteins and disease resistance proteins) were also found, suggesting that Tunisian durum germplasm may represent an important source of favourable alleles that can be used in future durum breeding programs to develop resilient cultivars better adapted to the challenges of climate change.