Pigments are essential to the life of all living organisms. Animals and plants have been the subjects of basic and applied research with the aim of determining the basis of the accumulation and physiological roles of pigments. In crop species, the edible organs show large variations in colour. In durum wheat grain, which is a staple food for humans, the colour is mainly due to two natural classes of pigment: carotenoids and anthocyanins. The carotenoids provide the yellow pigmentation of the durum wheat endosperm, and consequently of the semolina, which has important implications for the marketing of end products based on durum wheat. Anthocyanins accumulate in the aleurone or pericarp of durum wheat and provide the blue, purple and red colours of the grain. Both the carotenoids and the anthocyanins are known to provide benefits for human health, in terms of decreased risks of certain diseases. Therefore, accumulation of these pigments in the grain represents an important trait in breeding programs aimed at improving the nutritional value of durum wheat grain and its end products. This review focuses on the biochemical and genetic bases of pigment accumulation in durum wheat grain, and on the breeding strategies aimed at modifying grain colour.

The renewed focus on cereal landraces is a response to some negative consequences of modern agriculture and conventional breeding which led to a reduction of genetic diversity. Cereal landraces are still cultivated on marginal lands due to their adaptability to unfavourable conditions, constituting an important source of genetic diversity usable in modern plant breeding to improve the adaptation to abiotic or biotic stresses, yield performance and quality traits in limiting environments. Traditional agricultural production systems have played an important role in the evolution and conservation of wide variability in gene pools within species. Today, on-farm and ex situ conservation in gene bank collections, together with data sharing among researchers and breeders, will greatly benefit cereal improvement. Many efforts are usually made to collect, organize and phenotypically and genotypically analyse cereal landrace collections, which also utilize genomic approaches. Their use in breeding programs based on genomic selection, and the discovery of beneficial untapped QTL/genes/alleles which could be introgressed into modern varieties by MAS, pyramiding or biotechnological tools, increase the potential for their better deployment and exploitation in breeding for a more sustainable agricultural production, particularly enhancing adaptation and productivity in stress-prone environments to cope with current climate changes.

A durum wheat consensus linkage map was developed by combining segregation data from six mapping populations. All of the crosses were derived from durum wheat cultivars, except for one accession of T. ssp. dicoccoides. The consensus map was composed of 1,898 loci arranged into 27 linkage groups covering all 14 chromosomes. The length of the integrated map and the average marker distance were 3,058.6 and 1.6 cM, respectively. The order of the loci was generally in agreement with respect to the individual maps and with previously published maps. When the consensus map was aligned to the deletion bin map, 493 markers were assigned to specific bins. Segregation distortion was found across many durum wheat chromosomes, with a higher frequency for the B genome. This high-density consensus map allowed the scanning of the genome for chromosomal rearrangements occurring during the wheat evolution. Translocations and inversions that were already known in literature were confirmed, and new putative rearrangements are proposed. The consensus map herein described provides a more complete coverage of the durum wheat genome compared with previously developed maps. It also represents a step forward in durum wheat genomics and an essential tool for further research and studies on evolution of the wheat genome.