The conversion of raw barley (Hordeum vulgare L.) to malt requires a process of controlled germination, where the grain is submerged in water to raise the moisture content to >40%. The transmembrane proteins, aquaporins, influence water uptake during the initial stage of controlled germination, yet little is known of their involvement in malting. With the current focus on sustainability, understanding the mechanisms of water uptake and usage during the initial stages of malting has become vital in improving efficient malting practices. In this study, we used quantitative proteomics analysis of two malting barley genotypes demonstrating differing water-uptake phenotypes in the initial stages of malting. Our study quantified 19 transmembrane proteins from nine families, including seven distinct aquaporin isoforms, including the plasma intrinsic proteins (PIPs) PIP1;1, PIP2;1, and PIP2;4 and the tonoplast intrinsic proteins (TIPs) TIP1;1, TIP2;3, TIP3;1, and TIP3;2. Our findings suggest that the presence of TIP1;1, TIP3;1, and TIP3;2 in the mature barley grain proteome is essential for facilitating water uptake, influencing cell turgor and the formation of large central lytic vacuoles aiding storage reserve hydrolysis and endosperm modification efficiency. This study proposes that TIP3s mediate water uptake in malting barley grain, offering potential breeding targets for improving sustainable malting practices.

中文翻译：

---

推进可持续制麦实践：水通道蛋白作为潜在育种目标，可改善大麦（Hordeum vulgare L.）受控发芽期间的吸水量

将生大麦 ( Hordeum vulgare L.)转化为麦芽需要一个受控发芽过程，其中将谷物浸入水中以将水分含量提高到 >40%。跨膜蛋白、水通道蛋白在受控发芽的初始阶段影响水的吸收，但人们对它们在麦芽制造中的作用知之甚少。随着当前对可持续性的关注，了解麦芽制造初始阶段的水吸收和使用机制对于提高麦芽制造效率变得至关重要。在这项研究中，我们对两种啤酒大麦基因型进行了定量蛋白质组学分析，证明了啤酒酿造初始阶段不同的吸水表型。我们的研究定量了来自 9 个家族的 19 种跨膜蛋白，包括 7 种不同的水通道蛋白亚型，包括血浆内在蛋白 (PIP) PIP1;1、PIP2;1 和 PIP2;4 以及液泡膜内在蛋白 (TIP) TIP1;1、TIP2;4。 3、提示3；1和提示3；2。我们的研究结果表明，成熟大麦籽粒蛋白质组中 TIP1;1、TIP3;1 和 TIP3;2 的存在对于促进水分吸收、影响细胞膨胀以及有助于储存储备水解和胚乳修饰的大型中央裂解液泡的形成至关重要效率。这项研究提出，TIP3 可以调节啤酒大麦谷物的水分吸收，为改善可持续啤酒生产实践提供潜在的育种目标。