Improving the processability of malting barley

在所有的谷物中，大麦是在最多样化的环境范围内种植的，因为它更耐受压力条件。用于酿造和蒸馏的麦芽是主要的工业用途，年需求量为2000万吨，约占世界产量的15%。在欧盟，用于酿造麦芽的作物比例要高得多，例如在英国，略低于30%。目前世界啤酒产量为18.5亿hl，是迄今为止麦芽的主要消费国。麦芽和啤酒的生产是在大规模的机械化规模上进行的，系统根据目标生产周期进行了优化。虽然植物育种已经改进了麦芽提取物，从而提高了每吨麦芽可生产的公升啤酒，但麦芽发酵器和啤酒酿造商仍然遇到不能正确处理的问题批次，例如，由于过多的蛋白质和/或细胞壁残留物，可发酵液与残渣固体的分离可能会减慢甚至停止。这种情况会导致生产延误，并产生清洁和残渣处理费用。因此，在英国酿造和蒸馏研究所列出的英国啤酒大麦的理想特性清单上，易加工性仅次于麦芽提取物。可加工性问题在不太适合麦芽的样品中更为明显，因为即使是麦芽品质较差的品种也能提供足够水平的麦芽浸出物，并在最佳条件下进行有效的加工。由于大多数麦芽试验都是从被确定为生产优质麦芽样品的地点进行的，一旦推荐了一个品种并进行了大规模种植，通常就会出现加工性问题。这是对植物育种和终端用户时间和资源的浪费，必须找到一种战略，以便能够在广泛的环境条件下选择和推广满足终端用户需求的品种。这一目标对英国(和世界)农业将变得越来越重要，因为气候变化可能会导致啤酒大麦生产的环境更加严酷和多变。我们在重要经济性状的遗传分析方面拥有丰富的经验，并已经在一组超过500个英国精英大麦品系上积累了一系列表现(表型)数据。此外，我们拥有这些品系的DNA指纹，并在结合这些数据集进行分析方面经验丰富，这些分析旨在识别大麦染色体上与表现差异相关的特定区域。我们将从500个大麦品系中选择100个春大麦和100个冬大麦品系的亚组，并在试验中将它们种植在旨在对比谷粒含氮量的制度下，从而提供麦芽加工能力的对比。通过将可加工性数据与基因数据相结合，我们将能够将影响麦芽可加工性差异的大麦染色体区域联系起来。当我们预计影响麦芽加工性的成分在谷物发育过程中被合成并在萌发过程中被降解时，我们还将在阶段从试验中的一小部分品系中提取RNA样本，并分析每个品系在每个阶段的基因表达谱。通过选择已知加工性不同的品系，我们可以比较“好”品系和“差”品系的总体模式，以筛选出差异表达的基因，从而可能参与加工性的控制。我们将用这种方法分析的50,000个基因都在大麦染色体上有一个已知的位置，所以我们可以将表达分析的结果与关联分析的结果进行比较，看看是否有共定位的基因。然后，我们将比较表达分析中与关联分析中的区域位于同一位置的基因的DNA序列，以检测是否有序列变异与加工能力的差异有关。然后，结果将通过更大规模的酿造测试进行测试，并通过对一小部分独立生产线的分析来验证。

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.