Improving the processability of malting barley

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.

We will grow 200 elite barley lines in replicated field trials at two sites for two years and collect seed and malting quality phenotypes. Utilising resources developed previously from a number of funding sources, including BBSRC, we will assemble SNP polymorphism data upon the lines which we will then use in QTL x E association analyses, with correction for structure, to identify genomic regions associated with malt processability. Our experience of association analyses is that we detect QTL for traits with heritabilities above 5% in such populations and we expect the heritability of processability to be greater. Effects detected under low and high nitrogen conditions are more likely to be effects associated with discrimination of lines with good and poor extract levels and less likely to reflect processability differences. We will target QTL x E effects that are mainly expressed under high nitrogen conditions as these will reflect effects that characterise lines found to have processing problems. We will augment these findings by using Agilent microarrays with 50,000 predicted barley gene models to study the transcriptional profiles of lines known to contrast for processability. We will sample endosperm tissue from the low and high nitrogen trial sites at stages coinciding with expression of cell wall synthesising genes during grain development and one coinciding with cell wall breakdown and proteolysis during malting. The location of all 50,000 gene models on barley chromosome maps is known and we will focus upon regions where up- or down-regulated genes are co-located with effects detected in the association analyses. We will then compare the sequences for such a gene obtained from a subset of lines contrasting for processability to see if any variants co-segregate with phenotype. Those that do will be validated against an independent test panel with pre-existing phenotypic data and then released to the breeding and end-user community for deployment.

Academic Impact
The project will generate data that will guide and influence researchers working upon:
1. Cell wall synthesis in the developing grain
2. Protein synthesis and deposition in developing grain
3. Seed shape, size and uniformity
4. Cell wall breakdown during germination (malting)
These are issues that researchers worldwide are working on as well as within the UK so the project will advance the worldwide knowledge base of the 4 areas outlined above, all of which are globally significant.

Economic and Societal Impact
The project will have a major economic impact as it will help safeguard malting barley premiums that are currently worth £377/ha to the malting barley grower. This will be achieved by the project's impact upon the commercial barley breeding sector where CIRC members will be able to utilise marker technology to select lines with good processability instead of conduction a full malting analysis which can cost in excess of £150ex VAT (NIAB Labtest). The availability of selectable markers thus represents a significant saving over phenotypic testing and thus has an immediate cost saving in plant breeding programmes. A greater saving is that achieved indirectly through the elimination of plant breeding, seed multiplication and official testing resources in the selection of promising malting barley varieties that ultimately are found to have processability problems when they are grown over a wider range of environments. An exact figure for this sum will depend upon the stage at which a variety fails but could cost the plant breeding industry alone up to between £0.5 - £1million for each failure. In addition to this amount, end-users who try to utilise varietal lots that have processing problems face production delays and cleaning costs. Given that each tonne of malt currently costs a brewer £390/t and that malting lots can be up to 250t, the loss can be nearly £100k to the brewer just in raw material costs for each malting batch purchased with processability problems.

The project therefore will contribute towards the sustainability of the malting barley market in the UK, which will have added benefits of maintaining the diversity of agricultural crops grown in the UK. As malting barley is grown with a lower nitrogen application than wheat or feed barley, this will have the added environmental benefit of preventing the polluting consequences of added fertiliser applications that would arise if malting barley growers switched to winter wheat or feed barley if their market collapsed. Maltings, craft breweries and especially distilleries tend to be situated in rural areas and play a key part in maintaining employment opportunities and hence the quality of life in their surroundings so the success of this project will contribute to local prosperity.