High molecular weight glutenin gene diversity in Aegilops tauschii demonstrates unique origin of superior wheat quality

Abstract

Central to the diversity of wheat products was the origin of hexaploid bread wheat, which added the D-genome of Aegilops tauschii to tetraploid wheat giving rise to superior dough properties in leavened breads. The polyploidization, however, imposed a genetic bottleneck, with only limited diversity introduced in the wheat D-subgenome. To understand genetic variants for quality, we sequenced 273 accessions spanning the known diversity of Ae. tauschii. We discovered 45 haplotypes in Glu-D1, a major determinant of quality, relative to the two predominant haplotypes in wheat. The wheat allele 2+12 was found in Ae. tauschii Lineage 2, the donor of the wheat D-subgenome. Conversely, the superior quality wheat allele 5+10 allele originated in Lineage 3, a recently characterized lineage of Ae. tauschii, showing a unique origin of this important allele. These two wheat alleles were also quite similar relative to the total observed molecular diversity in Ae. tauschii at Glu-D1. Ae. tauschii is thus a reservoir for unique Glu-D1 alleles and provides the genomic resource to begin utilizing new alleles for end-use quality improvement in wheat breeding programs.

Population genomic analysis of Aegilops tauschii identifies targets for bread wheat improvement

“…tauschii, L3, which also contributed to the extant wheat genome. For example, a glutenin allele required for superior dough quality was recently found to be of L3 origin 46 . L3 accessions are restricted to present-day Georgia and may represent a relict population from a glacial refugium as observed in Arabidopsis 47 .…”

Advances in the Mining of Disease Resistance Genes from Aegilops tauschii and the Utilization in Wheat

“…In the study of high-yield genes, Wan et al [ 40 ] found a major QTL for leaf sheath hairiness (LSH) on Aegilops tauschii 4DS, and the allele of this QTL locus was significantly positively correlated with the increase in grain yield, grain weight, and grain weight per spike. Delorean et al [ 41 ] sequenced 273 accessions spanning the known diversity of Aegilops tauschii . They found that Aegilops tauschii is a reservoir for unique Glu-D1 alleles and provides a genomic resource for improving wheat quality.…”

Evolution and origin of bread wheat

“…HMW glutenins from the D subgenome have contributed to wheat baking quality ( Orth and Bushuk, 1973 ; Shewry, 2009 ). Likewise, the Transcaucasian D lineage contains an HMW glutenin subunit contributing to superior baking quality ( Delorean et al, 2021 ). Hence, a likely scenario is that bread wheat was formed in the south Caspian under domestication, that a few additional introgressions with strangulata lines took place such as the Ae.…”

“…Tauschii greatly extended the range of adaptation of hexaploid wheats to a more continental climate over the continental plateaus of Asia and the colder temperate areas in eastern, central, and northern Europe ( Feldman, 2001 ; Zohary et al, 2012 ). The D genome also contributed resistance to several fungal diseases ( Appels and Lagudah, 1990 ; Yildirim et al, 1995 ) as well as many desirable grain qualities ( Orth and Bushuk, 1973 ; Delorean et al, 2021 ) that promoted bread wheat spread and global adoption as the preferred wheat type and the preferred cereal compared to barley.…”