The effects on grain endosperm structure of an introgression from <Emphasis Type="Italic">Aegilops speltoides</Emphasis> Tausch. into chromosome 5A of bread wheat

The endosperm structure of the wheat kernel determines its end-use quality. The known diversity in endosperm structure is related to the Pina-D1 and Pinb-D1 genes comprising the Ha locus on chromosome 5DS. We studied the effect of a gene introduced into bread wheat from the diploid relative, Aegilops speltoides, a putative donor of the B genome. Grain hardness and vitreousness were investigated in lines with homoeologous introgressions into chromosome 5A of spring wheat cultivar ‘Rodina’. One introgression changed the endosperm texture from hard to soft and had the same effect when transferred to other wheat genotypes. This indicated that its action was analogous to the dominant allele at the Ha locus. The temporary symbol Ha–Sp is given to the gene. Segregation for vitreousness in F₃ offspring from monosomic hybrids was also investigated. Genetic variability for endosperm structure in wheat may be extended by manipulating both hardness and vitreousness. Wheat germplasm with introgressions from wild relatives can increase the genetic variability of milling characteristics.