Abstract Protein Z is a major component in beer foam. Two-dimensional electrophoresis was used to analyze wort proteins of two Australian (Buloke and Commander) and two Canadian (CDC Meredith and Bentley) varieties. The Canadian barley contained more abundant proteins from MW 40–45 kDa (pI 5 to 7). These proteins were identified as either protein Z4 or protein Z7 using liquid chromatography–mass spectrometry. Full-length gene of protein Z4 and Z7 were sequenced from Canadian and Australian barleys. Sequence differences were identified in the coding region and upstream regions of the two genes, resulting in protein sequence and expression variations. Molecular markers were designed according to the indels in the upstream regions of protein Z4 and Z7 genes. These markers were highly correlated to wort protein Z content in Canadian and Australian varieties. The Canadian barleys contained ‘high level’ genotypes for protein Z4 and Z7 while most Australian barleys had ‘low level’ genotypes for protein Z4, Z7 or both. The markers identified in this study provide a valuable tool for the selection of protein Z alleles in marker-assisted breeding. Total protein Z content was assessed using different steeping conditions, and increasing air-rest time increased protein Z content in 15 varieties.

中文翻译：

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澳大利亚和加拿大大麦中麦芽汁蛋白 Z 的表型和等位基因变异

摘要 蛋白质Z是啤酒泡沫的主要成分。二维电泳用于分析两种澳大利亚（Buloke 和 Commander）和两种加拿大（CDC Meredith 和 Bentley）品种的麦芽汁蛋白质。加拿大大麦含有更丰富的蛋白质，分子量为 40–45 kDa（pI 5 到 7）。使用液相色谱-质谱法将这些蛋白质鉴定为蛋白质 Z4 或蛋白质 Z7。从加拿大和澳大利亚大麦中对蛋白质 Z4 和 Z7 的全长基因进行测序。在两个基因的编码区和上游区鉴定出序列差异，导致蛋白质序列和表达变异。根据蛋白Z4和Z7基因上游区域的插入缺失设计分子标记。这些标记与加拿大和澳大利亚品种的麦汁蛋白 Z 含量高度相关。加拿大大麦包含蛋白质 Z4 和 Z7 的“高水平”基因型，而大多数澳大利亚大麦具有蛋白质 Z4、Z7 或两者的“低水平”基因型。本研究中鉴定的标记为在标记辅助育种中选择蛋白质 Z 等位基因提供了宝贵的工具。使用不同的浸泡条件评估总蛋白 Z 含量，增加空气静息时间会增加 15 个品种的蛋白 Z 含量。