The impact of emmer genetic diversity on grain protein content and test weight of hexaploid wheat under high temperature stress

High temperature has a negative impact on wheat grain quality and reduces market value. Emmer wheat (Triticum dicoccon Schrank), one of the earliest domesticated wheat species, is a source of genetic diversity for the improvement of heat and drought tolerance in modern wheat. However, the potential of emmer wheat for the improvement of grain physical quality under high temperature stress is little studied. A diverse set of 184 emmer-based hexaploid lines was developed by crossing emmer wheat with hexaploid wheat and backcrossing once to hexaploid wheat. These materials, seven hexaploid recurrent parents and seven commercial cultivars, were evaluated at two times of sowing (E1 and E2) in the field, in 2015–2016. The materials were genotyped using a 90 K SNP platform and these data were used to estimate the contribution of emmer wheat to the progeny. Significant phenotypic and genetic variation for grain physical quality traits including protein content and test weight was observed. High temperature significantly increased protein content and decreased test weight. Large scale field phenotyping identified emmer progenies with improved grain characteristic compared to their respective parents and commercial cultivars in both environments. A few families consistently produced higher trait means across environments compared to their recurrent parents. The emmer wheat parent contributed between 1 and 37% of the genome in emmer-based genotypes. Selected emmer derived lines with superior protein content and test weight, tended to have a greater genetic contribution from the emmer parent, ranging from 12 to 37% and 7–37% in E1 and E2, respectively. It was concluded that new genetic variation for seed traits, such as protein content and test weight, can be introduced to hexaploid wheat from emmer wheat. The newly developed emmer derivatives identified with enhanced grain quality under high temperature stress can potentially be used to improve grain quality through breeding.