Single seed descent: a tool to exploit durum wheat (Triticum durum Desf.) genetic resources

A large wealth of genetic diversity is present in the diversity centers of durum wheat. However, modern breeding selection methods are mostly based on improvement of élite lines which have a narrow genetic base; this limits a lot the genetic pool which breeders can exploit for the production of new varieties ready to face the predicted climate changes or adaptation to new cultivation areas. The oncoming changing climatic conditions claim for the need of finding new adaptation traits to both abiotic and biotic stresses to be introduced in modern élite varieties. These traits are often found in landraces stored in germplasm collections. The Eurisco database reports a total of over 17,000 durum accessions, some 6,800 of which are traditional varieties and/or landraces: Besides their incontestable usefulness, their great number hampers the possibility to explore their genepool. A different approach to reduce the number of genotypes to screen for new useful traits to use in breeding programs while maintaining a good representation of the genetic background, is the constitution of a working durum wheat collection selected by mean of a single seed descent (SSD) approach so far called SSD genotypes. The working collection, accounts for over approximately 450 genotypes representative of 40 countries mainly concentrated in the Mediterranean area and Horn of Africa. The SSD genotypes were subjected to large scale SNP screening by ILLUMINA Infinium iSelect 90k wheat chip and the data were analysed to assess the heterozygosity and the genetic diversity present in the SSD population. Moreover the population was preliminary phenotyped following field growth. Both analyses give the picture of a good level of genetic variability represented in the SSD genotypes. This makes this collection a good candidate for a new “genetool” for durum wheat breeding and research.