Association mapping of malting quality traits in UK spring and winter barley cultivar collections

,William T. B. Thomas,Joanne R. Russell,Luke Ramsay,Malcolm Macaulay,Paul D. Shaw,Allan Booth,Mark E. Looseley,J. Stuart Swanston,Robbie Waugh,Hazel Bull

doi:10.1007/s00122-020-03618-9

Abstract

Key messageHistorical malting quality data was collated from UK national and recommended list trial data and used in a GWAS. 25 QTL were identified, with the majority from spring barley cultivar sets.In Europe, the most economically significant use of barley is the production of malt for use in the brewing and distilling industries. As such, selection for traits related to malting quality is of great commercial interest. In order to study the genetic basis of variation for malting quality traits in UK cultivars, a historical set of trial data was collated from national and recommended list trials from the period 1988 to 2016. This data was used to estimate variety means for 20 quality related traits in 451 spring barley cultivars, and 407 winter cultivars. Genotypes for these cultivars were generated using iSelect 9k and 50k genotyping platforms, and a genome wide association scan performed to identify malting quality quantitative trait loci (QTL). 24 QTL were identified in spring barley cultivars, and 2 from the winter set. A number of these correspond to known malting quality related genes but the remainder represents novel genetic variation that is accessible to breeders for the genetic improvement of new cultivars.

Highlights

Barley (Hordeum vulgare) is the fourth largest cereal crop as measured by worldwide annual production
In total data from 2862 individual trials were collated, representing 1520 spring, and 1342 winter barley trials (Table 3). From this data Best Linear Unbiased Predictors (BLUPs) were calculated for 451 spring, and 407 winter varieties. These estimates were made for 26 spring malting quality traits and 25 winter traits, including grain quality, malt modification, wort attributes and process yield (Fig. 1)
Considering just the cultivars that had been placed on the AHDB Cereals and Oilseeds Recommended Lists and had been considered for Malting Barley Committee (MBC) approval, hot water extract (HWE) BLUPs were regressed against the year in which they were first recommended to determine if genetic progress had been made

Summary

Introduction

Barley (Hordeum vulgare) is the fourth largest cereal crop as measured by worldwide annual production (faostat.fao.org). Malt production is a carefully controlled process in which mature grains are germinated, generating and activating a variety of amylolytic; proteolytic and cell wall degrading enzymes (Briggs 2002). Together, these modify the carbohydrate and protein composition of the grain allowing the production of fermentable sugars during mashing, and efficient alcohol production during fermentation. The activity levels of amylolytic enzymes, produced during the malting process, can determine the levels of starch conversion (Evans et al 2005), whilst protein degradation can affect beer flavour through the amino acid composition of the wort (He et al 2014). As such, ‘malting quality’ is a generic term that refers to a disparate set of characteristics

Methods

Results

Conclusion