Plant Science Department, McGill University, Montreal, QC H9X 3V9, Canada.
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720.
Proc Natl Acad Sci U S A. 2017 Jul 18;114(29):7725-7730. doi: 10.1073/pnas.1701824114. Epub 2017 Jun 20.
Barley is the cornerstone of the malting and brewing industry. It is known that 250 quantitative trait loci (QTLs) of the grain are associated with 19 malting-quality phenotypes. However, only a few of the contributing genetic components have been identified. One of these, on chromosome 4H, contains a major malting QTL, QTL2, located near the telomeric region that accounts, respectively, for 28.9% and 37.6% of the variation in the β-glucan and extract fractions of malt. In the current study, we dissected the QTL2 region using an expression- and microsynteny-based approach. From a set of 22 expressed sequence tags expressed in seeds at the malting stage, we identified a candidate gene, (), which was differentially expressed and influenced malting quality. Transcript abundance and protein profiles of were studied in different malt and feed varieties using quantitative PCR, immunoblotting, and enzyme-linked immunosorbent assay (ELISA). The experiments demonstrated that TLP8 binds to insoluble (1, 3, 1, 4)-β-D glucan in grain extracts, thereby facilitating the removal of this undesirable polysaccharide during malting. Further, the binding of TLP8 to β-glucan was dependent on redox. These findings represent a stride forward in our understanding of the malting process and provide a foundation for future improvements in the final beer-making process.
大麦是麦芽和酿造行业的基石。据了解，250 个谷物的数量性状位点（QTL）与 19 个麦芽质量表型相关。然而，只有少数遗传成分已被确定。其中之一位于 4H 染色体上，包含一个主要的麦芽 QTL，QTL2，位于端粒区域附近，分别占麦芽β-葡聚糖和提取物分数变化的 28.9%和 37.6%。在当前的研究中，我们使用基于表达和微同线性的方法对 QTL2 区域进行了剖析。从一组在麦芽阶段种子中表达的 22 个表达序列标签中，我们鉴定出一个候选基因，（），其表达水平存在差异，并影响麦芽质量。使用定量 PCR、免疫印迹和酶联免疫吸附测定（ELISA）研究了不同麦芽和饲料品种中 TLP8 的转录丰度和蛋白图谱。实验表明，TLP8 与谷物提取物中的不溶性（1,3,1,4）-β-D 葡聚糖结合，从而在麦芽过程中促进了这种不期望的多糖的去除。此外，TLP8 与β-葡聚糖的结合依赖于氧化还原。这些发现代表了我们对麦芽过程的理解向前迈进了一步，并为未来改进最终的啤酒生产过程提供了基础。
