Expression of dominant marker genes of barley in wheat-barley hybrids

Seven dominant marker genes controlling morphological characters of barley were introduced into a wheat genetic background through hybridization between a Japanese bread wheat cultivar, Shinchunaga, and barley marker stocks. F-1 hybrids and their derivatives were analyzed by C-banding to confirm the presence and dosage of particular barley chromosomes carrying the marker genes. The genes for black lemma (B, located on chromosome 1H), pubescent leaf blade (Pub, 3H), hairy leaf sheath (Hs, 4H) and hooded lemma (K, 4H) were expressed in the F-1 hybrids, but generally to a lesser extent than in the parental barley accessions. F-1 hybrids having two copies of the B or Hs genes showed more pronounced phenotypes. In backcrossed progenies, each of which had a single copy of the barley marker gene in a hexaploid wheat background, the B and K phenotypes were less pronounced than in the F, hybrids, and the Pub phenotype was not observed. These four genes appear to be expressed in proportion to their dosage relative to the ploidy levels of the wheat background. The remaining three marker genes, brittle rachis (Bt-Bt2, 3H), blue aleurone (Pi, 4H) and short-upper-leaves (SuI) did not appear to express their characteristic phenotypes in any of the respective hybrids. Possible causes for reduced expression or complete suppression of the dominant barley genes in the wheat-barley hybrids are discussed. Dominant barley marker genes which are expressed in the hybrids would be useful for manipulating barley chromosomes in wheat backgrounds.