A recently accepted paper in the October 2026 issue of our journal serves as an exemplar of how researchers are using techniques and genetic material to potentially improve important crop species on a world scale. This paper ‘Genetic diversity, population structure, and enhancing selection efficiency in wheat pre-breeding using the CGIAR mid-density DArTag panel’ considers how work at ICARDA, IAV Agronomic and Veterinary Institute has used ICARDA material in the pre-breeding space, which is to say the focussed production of novel genotypes that could be a source of key traits, such as rust resistance, grain yield, heat tolerance and grain quality. This type of horizon-scanning work will probably feed into the production of important new varieties that will address future needs such as climate change or finding resistance genes for new fungal pathovars that could cause serious disease epidemics in the future.
As many will know, wheat is fourth out of the seven most important crops contributing to crop global impact and human food security alongside the other six (sugar cane, maize, rice, potato, soybean and cassava). Wheat is a hexaploid species and therefore intrinsically one of the more difficult species to breed, having, as it does, not only three versions of a given trait, but is also an inbreeding species, necessitating emasculation of breeding material to ensure targeted crossing in the glasshouse.
Furthermore, the elite crop we grow today arose from spontaneous hybridization between wild grasses. The first initial hybridization of the first two parents, namely Triticum urartu (forming the AA genome) and an unidentified second species related to Aegilops speltoides (forming the BB genome), represents an initial genetic diversity bottleneck and probably occurred a limited number of times between 500 and 150 thousand years ago. This narrowing of allelic diversity within the gene pool was exacerbated by the second spontaneous hybridization with another diploid (Ae. tauschii AKA goatgrass forming the DD genome), which occurred around 9000 years ago and, therefore, created a second tighter bottleneck. Since this second hybridization represents a cross between a tetraploid and a diploid, it is unlikely that this occurred more than a handful of times, thereby providing little potential for allelic diversity within the DD genome.
This double reduction in the potential gene pool represents a challenge to pre-breeding teams. It is exciting, therefore, to see this paper by Fatima et al., who have looked at a large panel of material developed by ICARDA. The initial rehybridization of parental material to extend diversity undertaken by ICARDA has now been mapped using a state-of-the-art DArTag panel to identify specific trait subsets. They have found that ‘A considerable proportion of markers identified in introgressed regions are linked to key traits.’ These will therefore have great potential for use by breeders and research teams and are likely to be reliable in Marker Assisted Selection work, being stable across the accessions that they considered.
