Mechanisms underlying variation in barley hull adhesion

大麦壳附着力变化的机制

基本信息

批准号：
BB/R010315/1
负责人：
Sarah McKim
金额：
$ 62.94万
依托单位：
University of Dundee
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FR010315%2F1
关键词：
Mechanisms underlying variation barley hull

项目摘要

This research explores a central but little studied problem in plant biology - how do plant surfaces influence plant architecture? We know that the protective cuticle covering the plant body, beyond preventing water loss and pathogen invasion, also ensures that closely growing plant organs remain separate and plays important roles in organ absicssion. However, less is known about the biology underlying plant interfaces that fuse, such as in tubular flowers, or organs that stick together as in the barley grain. In the latter, a species-specific pathway leads to secretion of a special cementing layer onto the outer pericarp cuticle. Loss of this layer, caused by mutations in a single master regulatory factor, NUDUM (NUD), occurred once during barley cultivation, leading to a complete loss of hull adherence or 'naked' grain, ideal for human consumption. However, most barley grown in the UK is used for animal feed and malt where 'covered' grain, retaining the adherent hull, is preferred as hulls protect the germ and aid in filtration after malting. Thus, the changing relationship of the hull to the grain is a critical quality that largely determines barleys downstream uses. Despite this, we understand practically nothing about the steps between NUD expression and the extrusion of the cementing material on the pericarp or the chemistry explaining the adherent properties of the layer.Genetic variation in newer elite barley malting cultivars is linked to an increasing incidence of a highly undesirable, intermediate phenotype whereby grain partially sheds its hull during harvest or processing, a phenomenon called 'skinning'. However, identifying the causal variation underlying skinning has proved very difficult, due to its environmental sensitivity and lack of robust screening methods, so to date breeders do not have genetic markers to help control this trait. In addition to addressing these important agronomic concerns, we are interested in identifying the genes and genetic mechanisms underlying skinning since these alleles may represent defective steps along unresolved NUD-driven pathway(s). Moreover, by characterising the molecular and chemical changes occuring in skinning, we may reveal the critical features of the cementing layer and/or other grain characters which influence hull adhesion that are lost in skinning mutants.To circumvent issues of studying the cultivated germplasm for quantitative skinning variation, we have assembled a panel of mutants with stable skinning phenotypes. We screened a wax-deficient collection of mutants in a single near-isogenic background and identified a small subset that show defective hull adhesion. This foundation work provides a robust and genetically powerful platform to dissect the molecular, chemical and genetic mechanisms that explain variation in hull adhesion.Our panel suggests that specific components of the surface lipid regulatory pathway may be defective in grain that skins. In this proposal, we seek to define the chemical and ultrastructural surfaces changes associated with hull adhesion and how they are altered by skinning loci. We will also reveal related changes in gene expression, both globally and on a tissue-specific level, that promote hull adherence and assess their importance to the skinning phenotype. Furthermore, we will identify individual genes that control skinning and evaluate diversity at these loci in cultivated germplasm, a critical milestone which will resolve which allelic variants track with incidence of skinning and allow us to develop markers for use in breeding. Taken together, our work will reveal the chemical and genetic components that cause partial loss of adherent hulls in barley, closing a vast knowledge gap about a critical grain quality trait, and delivering routes to improved germplasm selection

这项研究探讨了植物生物学中的一个中心但很少研究的问题 - 植物表面如何影响植物建筑？我们知道，覆盖植物体的保护性角质层除了防止水流失和病原体入侵之外，还确保了密切生长的植物器官保持分开，并在器官脓肿中起重要作用。但是，对于融合的生物学界面（例如在管状花朵中，或像大麦谷物中粘合在一起的器官）的生物学知之甚少。在后者中，物种特异性的途径导致特殊的胶结层分泌到外果皮表皮上。由单个主调节因子裸体（NUD）突变引起的该层的损失发生在大麦栽培过程中一次，导致船体依从性或“裸”谷物的完全丧失，非常适合人类食用。但是，在英国种植的大多数大麦用于动物饲料和麦芽，其中“覆盖”谷物保留了粘附的船体，因为船体保护细菌并有助于麦芽过滤，因此首选粘附的船体。因此，船体与谷物的不断变化是一种关键品质，在很大程度上决定了Barleys下游用途。 Despite this, we understand practically nothing about the steps between NUD expression and the extrusion of the cementing material on the pericarp or the chemistry explaining the adherent properties of the layer.Genetic variation in newer elite barley malting cultivars is linked to an increasing incidence of a highly undesirable, intermediate phenotype whereby grain partially sheds its hull during harvest or processing, a phenomenon called 'skinning'.但是，由于其环境敏感性和缺乏强大的筛查方法，识别皮肤造成的因果变异已被证明非常困难，因此迄今为止，育种者没有遗传标记来帮助控制这一特征。除了解决这些重要的农艺问题外，我们还有兴趣识别皮肤皮肤上的基因和遗传机制，因为这些等位基因可能代表沿未解决的裸体驱动途径（S）的有缺陷的步骤（S）。此外，通过表征皮肤中发生的分子和化学变化，我们可能会揭示胶结层和/或其他谷物特征的关键特征，这些特征会影响皮肤突变体中丢失的船体粘附。为了避免研究定量皮肤变化的耕种种质的问题，我们已经与稳定的皮肤斑点组装了突变体的面板。我们在单个近乎异构的背景下筛选了缺乏蜡的突变体的集合，并确定了一个小子集，该子集显示出缺陷的船体粘附。这项基础工作提供了一个强大且具有遗传功能的强大平台，以剖析解释船体粘附变化的分子，化学和遗传机制。您的面板表明，表面脂质调节途径的特定成分可能在皮肤的谷物中有缺陷。在此提案中，我们试图定义与船体粘附相关的化学和超微结构表面变化，以及如何通过皮肤基因座改变它们。我们还将在全球和组织特异性水平上揭示基因表达的相关变化，从而促进船体依从性并评估其对皮肤表型的重要性。此外，我们将确定各个基因控制皮肤上的皮肤和评估这些基因座的多样性，这是一个关键的里程碑，这将解决具有皮肤发病率的等位基因变体，并使我们能够开发用于育种的标记。综上所述，我们的工作将揭示出大麦中固定船体部分损失的化学和遗传成分，从而缩小了有关关键谷物质量特征的巨大知识差距，并提供了改善种质选择的路线