Toward a DNA fingerprint to identify barley cultivars that fit specific brewers’ needs

Technical Session 05: Malts and Grain Session
Richard D Horsley, North Dakota State University, Department of Plant Sciences, Fargo, ND USA
Co-author(s): Magan Lewis, North Dakota State University, Department of Plant Sciences, Fargo, ND, USA; Fabio Pedraza-Garcia, Seeds 2000, Breckenridge, CO, USA; Ana Correa-Morales, North Dakota State University, Department of Plant Sciences, Fargo, ND, USA; Shiaoman Chao, USDA-ARS, Cereal Crops Research Unit, Fargo, ND, USA; Ronshuang Lin, University of Maryland, College Park, MD, USA; Paul Schwarz, North Dakota State University, Department of Plant Sciences, Fargo, ND, USA

ABSTRACT: Brewers in the United States who use six-rowed barley (Hordeum vulgare L.) have historically used cultivars with similar malt quality profiles. Around the year 2000 this changed, with some brewers preferring cultivars that produce higher levels of alpha-amylase and have increased protein modification during malting, while other brewers prefer cultivars that have moderate levels of these two characters. Two cultivars that meet these differing criteria are Stander, which produces increased levels of alpha-amylase, soluble protein, and free amino nitrogen (FAN); and Robust, which produces moderate levels of these malt quality parameters. In addition, Robust and Stander differ in their resistance to preharvest sprouting (PHS), with Stander being very susceptible and Robust being moderately resistant to PHS. An interesting characteristic of Stander and Robust is that they are very closely related. This feature should make it possible for us to determine the genetic basis for the dissimilarities in the two cultivars and to use this information to design a marker assisted breeding strategy for developing cultivars that meet specific brewers’ needs. The markers associated with specific quality parameters in Robust or Stander can be thought of as their “fingerprint.” Geneticists call this fingerprint a haplotype. A doubled-haploid mapping population from the cross Robust × Stander was developed. A genetic map for this cross comprised of single nucleotide polymorphism (SNP), simple sequence repeat (SSR), and diversity array technology (DArT) markers was constructed. The polymorphic markers were grouped into 19 linkage groups, which were associated with six of the seven barley chromosomes. Chromosomes 2H, 4H, and 6H had relatively large portions of the chromosomes mapped, while chromosomes 1H, 3H, and 5H had many small segments mapped. Because of the specific quality parameters required for malting barley, it is not surprising that only portions of the chromosomes were mapped. Many of the segments not mapped would be regions where genes controlling malt quality are fixed in a favorable state. Additionally, the regions where a map was constructed are likely to include the specific genes that determine the quality differences observed in Robust and Stander. The map constructed was used to identify quantitative trait loci (QTL) controlling seedling dormancy, alpha-amylase activity, soluble protein concentration, Kolbach index, FAN, wort beta-glucan, and concentrations of wort carbohydrates. QTL controlling correlated traits often mapped to similar sites. For example, QTL controlling alpha-amylase, Kolbach index, FAN, and wort color mapped to a similar region in chromosome 6H. A preliminary “fingerprint” or haplotype of markers that differentiate Robust-type from Stander-type barley cultivars will be discussed.

Richard Horsley is the barley breeder at North Dakota State University and head of the Department of Plant Sciences. Richard earned his Ph.D. and M.S. degrees in agronomy from North Dakota State University and his B.S. degree in agronomy from the University of Minnesota. The primary goal of his breeding project is to release and develop six-rowed and two-rowed malting barley varieties acceptable to barley producers in North Dakota, adjacent states, and the malting and brewing industry. Current research efforts include the determination of DNA “fingerprints” that differentiate varieties for specific brewer’s needs and identification of genes for resistance to preharvest sprouting.