Improving the processability of malting barley

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Of all the cereals, barley is grown over the most diverse environmental ranges as it is more tolerant of stress conditions. Malting for use in brewing and distilling is the major industrial usage with a demand of 20M t/yr, approximately 15% of world production. A much higher proportion of the crop is used for malting in the EU, e.g. just under 30% in the UK. World beer production is currently 1.85 billion hl and is thus by far the major consumer of malt. Production of malt and beer takes place on a large mechanised scale where systems are optimised to a target production cycle. Whilst plant breeding has improved the malt extract and thus the litres of beer that can be produced per tonne of malt, maltsters and brewers still encounter problem batches that do not process properly, e.g. because separation of fermentable liquid from residue solids can be slowed down or even halted by too much protein and/or cell wall residues. Such a situation causes production delays and incurs cleaning and residue disposal costs. Ease of processing (processability) is therefore second after malt extract on the Institute of Brewing and Distilling's 'wish list' of desirable characters for UK malting barley. Processability problems are much more apparent in samples that are less than ideal for malting as even poor malting quality varieties give adequate levels of malt extract and process efficiently when grown under optimum conditions. As most malting tests are conducted from sites identified as producing good malting quality samples, processability problems generally appear once a variety has been recommended and grown on a larger scale. This is a waste of plant breeding and end-user time and resources and a strategy must be found to enable the selection and promotion of varieties that meet end-user needs under a wide range of environmental conditions. This target will become increasingly important to UK (and world) agriculture as climate change is likely to results in harsher and more variable environments for malting barley production.We have considerable experience in the genetic analysis of economically important traits and have already amassed a range of performance (phenotypic) data upon a set of over 500 UK elite barley lines. In addition, we have DNA fingerprints of each of these lines and are experienced in combining such datasets in analyses designed to identify specific regions on barley chromosomes that are associated with differences in performance. We will select subsets of 100 spring and 100 winter barley lines from the 500 and grow them in trials under regimes designed to contrast for grain nitrogen content and thus provide contrasts in malt processability. By combining the processability data with the genotypic data, we will be able to associate regions of barley chromosomes that effect differences in malt processability. We will also sample RNA from a smaller subset of the lines in trial at stages when we expect the components affecting malt processability are being synthesised during grain development and degraded during germination and analyse the gene expression profile of each line at each stage. By selecting lines that are known to differ in processability, we can compare the overall pattern of 'good' lines with that of 'poor' lines to filter out genes that are being differentially expressed and thus are likely to be involved in the control of processability. The 50,000 genes that we will assay this way all have a known location on barley chromosomes so we can compare the results from the expression analysis with those of the association analysis to see if any co-locate. We will then compare the DNA sequences of genes from the expression analysis that co-locate with regions from the association analysis to detect if any sequence variants are associated with differences in processability. Results will then be tested through larger scale brewing tests and validated through analysis of a small independent panel of lines.