Development of an Aegilops longissima substitution line with improved bread-making quality

• An Aegilops longissima (1Sl) addition line exhibited positive bread-making traits.
• A 1Sl substitution line with chromosome 1A of wheat [DSL1Sl(1A)] was created.
• [DSL1Sl(1A)] had a positive effect on dough strength and bread-making quality.
• HMW-GSs of 1Sl were longer than those of wheat and aligned with those of the D-genome.
• Chromosome 1A of wheat carries a minor hardness locus.

This study focuses on the effect of Aegilops longissima on wheat bread making quality. Chromosome 1Sl disomic addition line of Ae. longissima (DAL1Sl) had significantly higher dough strength, grain hardness, mixographic peak height, band width, and unextractable polymeric protein content compared with wheat. DAL1Sl also had additional glutenin and gliadin proteins contributed by Ae. longissima. The larger size of 1Sl coded HMW-GSs sequenced from DAL1Sl and their phylogenetic similarity to the D-genome-coded subunits were suspected to be one of the major reasons for the increased dough strength of DAL1Sl. To transfer the chromosome 1Sl genes responsible for the good bread-making quality to wheat, we generated a chromosome-specific disomic substitution line [DSL1Sl(1A)] by crossing DAL1Sl with nulli 1A tetra 1B genetic stock and further selection. Grain quality analysis revealed significantly lower grain hardness and significantly higher dough strength, farinograph development time, stability time, gluten index, bread loaf volume, and bread quality score in DSL1Sl(1A), compared with wheat. However, the increased bread loaf volume and quality were not proportional to the relatively higher increases in dough strength and gluten index, indicating importance of other traits influencing bread making quality. The presence of a minor hardness locus on chromosome 1A is speculated.