Changes in protein content, composition and dough quality: outcomes of Australian wheat breeding on varieties released from 1860 to 2015.

The maintenance and improvement in wheat quality remains a fundamental aim of Australian wheat breeding programs along with improvement in yield and disease resistance. This study explored the evolution in grain quality among Australian wheat varieties released over the past 150 years, examining aspects such as grain physical quality parameters, protein content and composition, dough rheology and baking quality traits. Our analysis indicated a decline in grain protein content over time, attributed to yield increases. The study revealed direct impacts of protein content and composition on end-use quality. Over the years, an increase in glutenin and UPP content and a decrease in gliadin were observed. This shift in protein composition was linked to the selection of specific alleles at all six glutenin loci on chromosome group 1, including the elimination of GluA1c and the consistent selection of GluB1i, GluB1u, GluA3b, GluB3h and the introduction of GluB1al. These genetic changes have significantly improved dough quality, evidenced by better dough mixing times, mixograph peak widths, dough stability and a reduction in weakening slope and softening values. Although no improvement was observed in loaf volume across modern versus older varieties, there was a notable enhancement in loaf volume relative to protein percentage in modern varieties, indicating an improvement in protein quality. This research underscores the impact of genetic selection on protein composition in contemporary versus older wheat varieties, leading to marked improvements in grain quality. Furthermore, the exploration of old wheat varieties has uncovered varieties with high protein content and quality, presenting opportunities for future breeding programs to develop new varieties aimed at satisfying both domestic and international market demands.