Malting quality quantitative trait loci on a high-density map of Mikamo golden × Harrington cross in barley (Hordeum vulgare L.)

A high-density map consisting of 550 markers was constructed based on the segregation data of 95 doubled-haploid lines (DHLs) derived from the cross between a Japanese barley cultivar, Mikamo Golden and a North American barley cultivar, Harrington (MH-DHLs). Quality traits of malt extract (EX), total nitrogen (TN), soluble nitrogen (SN), Kolbach index (KI), diastatic power (DP), wort beta-glucan (WG) and viscosity (VS) were determined in three site/year crops. Quantitative trait loci (QTL) analyses were performed with these quality data sets, using the linkage map. Major QTL controlling EX, SN and KI were mapped on terminal region of 5H with Harrington as effective allele. Another QTL controlling EX was mapped on 2H with Mikamo Golden as effective allele. QTL controlling TN, DP, WG and VS were detected variably in terms of flanking markers and chromosomes depending on site/year. Cleaved amplified polymorphic sequences (CAPS) markers for EX based on the QTL detected on 2H and 5H were developed. Analysis of EX and genotypes of 33 malting barley cultivars from around the world as well as MH-DHLs revealed that the two CAPS marker on 2H and 5H affect EX by a significant difference, suggesting that the two CAPS markers were valuable for marker-assisted selection in malting barley breeding.