Genetic mapping of beta-glucan and beta-glucanase activity loci in malting barley (Hordeum vulgare L.)
Date
2016-07-18
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0003-1067-4431
Type
Thesis
Degree Level
Masters
Abstract
Low concentrations of (1,3;1,4)-β-ᴅ-glucan are desired in malt/wort created from barley (Hordeum vulgare L.) to ensure efficiency during brewing. This goal can be achieved through low grain β-glucan content, high malt β-glucanase activity, or a combination thereof. Evaluation of these traits is time-consuming and expensive since malting must occur before analysis, thus they are ideal for the identification of associated markers to permit marker-assisted selection.
Two genetic mapping approaches were taken to evaluate these traits. First, a bi-parental QTL mapping population was developed from the Western Canadian two-row, spring, hulled varieties CDC Meredith and CDC Kindersley. CDC Meredith has normal to higher grain β-glucan content and higher wort β-glucan content, while CDC Kindersley has normal to lower grain β-glucan content and very low wort β-glucan content. Secondly, a 92 member association mapping (AM) population was assembled consisting of two-row, spring, hulled elite malting breeding lines and varieties derived from eight different barley breeding programs focused on Western Canada. Both populations were grown over a two year period and assessed for kilned malt β-glucanase activity, grain, malt, and wort β-glucan content, plus green malt β-glucanase activity in the AM population. Both populations were genotyped using the Barley 9K iSELECT Genotyping BeadChip and the QTL population was also genotyped with DArTseq markers.
As expected, green malt β-glucanase activity typically had a stronger correlation to malt/wort β-glucan content than did either kilned malt β-glucanase activity or grain β-glucan content. Ten unique QTLs (four for grain β-glucan, two for malt β-glucan, and three for kilned malt β-glucanase) were identified in the QTL population and eight marker-trait associations were identified in the AM population for grain β-glucan, green/kilned malt β-glucanase, or a combination thereof. One common genomic region on chromosome 2H was identified in both studies which was associated with grain β-glucan content. In the QTL and AM populations, six and five QTLs and marker-trait associations identified were novel, respectively, while the others overlay previously identified regions. In some cases, underlying genes were identified which may explain the observed associations. Lines with high β-glucanase activity and heat stability were identified in the AM population, thus through crossing, lines possessing both of these beneficial traits could be generated. Further trials to collect data on these traits would be desirable to validate the identified markers and confirm the β-glucanase heat stability data.
Description
Keywords
β-glucan, β-glucanase, barley, Hordeum vulgare L., QTL mapping, association mapping, malt quality
Citation
Degree
Master of Science (M.Sc.)
Department
Plant Sciences
Program
Plant Science