Identification of molecular markers linked to ant28-484, a mutation that eliminates proanthocyanidin production in barley seeds

Barley (Hordeum vulgare L.) seed proanthocyanidins play a primary role in beer colloidal haze formation. The barley ant28-484 mutation eliminates proanthocyanidin synthesis and beer brewed with barley homozygous for ant28-484 exhibits intrinsic haze stability. The recessive nature of this mutation, coupled with the fact that the proanthocyanidin-free phenotype it confers is discernable only in maternal tissues of the seed, makes introgression of ant28-484 into new cultivars arduous. The goal of this study was to identify molecular markers for use in marker-assisted selection of ant28-484. An F₂ barley population derived from the cross Arapiles x Caminant was scored for ant28-484 segregation. DNA pools from F₂ plants homozygous for ant28-484 or the contrasting wild-type allele were used for bulked segregant RAPD analysis. RAPD bands differentiating the two DNA pools were then analyzed for linkage to ant28-484 in the F₂ population. Five linked RAPD markers were identified, with linkage estimates to ant28-484 ranging from 0 to 11 centimorgans (cM). Three of the markers were ]inked in cis to ant28.484 and two were linked in trans. The three most tightly linked RAPD markers were cloned, and southern analysis indicated that they represent low or single copy sequences. The ant28-484 mutation was localized to barley chromosome arm 3HL, on the basis of results of southern analysis with wheat-barley ditelosomic addition lines probed with the cloned RAPD markers and on the basis of linkage to the previously mapped isozyme locus Est4. These markers will enhance the efficiency with which ant28-484 can be introgressed into barley germplasm.