Mapping malting quality and yield characteristics in a north American two-rowed malting barley × wild barley advanced backcross population

Abstract

Due to the stringent quality requirements imposed by the US malting barley industry, barley breeders have been reluctant to introduce exotic germplasm into cultivar development programs. To determine whether wild barley (Hordeum vulgare ssp. spontaneum) contains favorable alleles for yield and malting quality characteristics, we mapped quantitative trait loci (QTL) for heading date, height, lodging, yield, and nine malting parameters important to the malting and brewing industry. Traits were mapped in a wild x cultivated barley BC2-derived advanced backcross mapping population. Harrington, the recurrent parent, is a North American two-rowed malting barley cultivar, and OUH602, the donor parent, is a wild barley accession that exhibits resistance to multiple barley diseases. The 98 derived lines were grown in replicated field trials at St. Paul and Crookston, MN in 2009–2011. One to four QTL were identified for each trait, for a total of 36 QTL. Trangressive segregants for increased yield were identified and four lines had higher yield than Harrington across all environments; however, for yield QTL the OUH602 alleles decreased the trait value. Wild barley alleles had both positive and negative effects on the malting traits of diastatic power, free amino nitrogen, and soluble protein. Combined with the previously identified QTL associated with resistance to fungal diseases, this population represents a rich resource for barley breeding. To facilitate future breeding and genetics studies with this population, a set of pre-introgression lines composed of 28 BC2-derived and 6 BC3-derived lines were identified that collectively contain introgressions across the entire OUH602 genome.