The Generation Gap - Mechanisms of maternal control on grain

在我们不断变化的世界中，了解谷物生产对于保障粮食安全至关重要。大麦是一种广泛种植的全球谷物，对我国具有巨大的经济重要性，也是一种强大的实验系统，可以识别和表征影响粮食产量和质量的过程。我们最近揭示了大麦中两个主要调节因子的重要性，它们改变了保护性和营养母体组织与填充谷物的富含淀粉和卡路里的子代组织之间的生长和存活平衡。我们假设，通过限制母体组织的大小和促进它们的消除来改变这种平衡，为增加颗粒大小和重量提供了所需的营养和空间。我们推测这种平衡的调节可能在野生大麦和栽培大麦之间有所不同，这可能解释了栽培大麦籽粒的改善。我们预测这一过程通过控制基因表达和信号传导在谷物组织中起作用，但确切的机制尚不清楚。造成这种知识差距的部分原因是，验证我们的预测是很棘手的：谷物是这些组织的混合体，调节因素在早期和晚期都起作用，使对组织和特定时间事件及其对谷物影响的准确评估变得复杂和混乱。我们建议通过在大麦中应用两项前沿技术来克服这些挑战。首先，我们将使用单细胞RNA测序来测量单个细胞内的基因表达，然后使用计算聚类来构建细胞群，并分析这些变化在整个谷物发育过程中的变化。其次，我们将应用新的诱导表达系统在特定时间改变调控因子的活性，以梳理早期和晚期功能对谷物参数的重要性。我们还将结合这些方法来评估在特定组织中激活的调节因子对邻近和远端组织中基因表达的影响。最后，我们将探讨这些细胞群在野生和栽培大麦之间的差异，并测试野生和栽培调节因子与籽粒参数的功能相关性。综上所述，我们的工作将定义谷物组织的发育轨迹及其对控制母系和子代生长和存活的调节因子的响应，从而显著推进我们对谷物发育的理解。

Understanding grain production in cereals is vital to safeguard food security in our changing world. Barley is a widely grown global cereal of vast economic importance to our country, and a powerful experimental system to identify and characterise processes that influence grain yield and quality. We recently revealed the importance of two master regulatory factors in barley which alter the balance between growth and survival of protective and nutritive maternal tissues versus the starchy, calorie-rich filial tissues filling the grain. We hypothesise that shifting this balance away from maternal tissues by limiting their size and promoting their elimination, provides the nutrients and space needed to increase grain size and weight. We speculate that the regulation of this balance may differ between wild and cultivated barleys, potentially explaining improved grain of cultivated barley. We predict that this process works by controlling gene expression and signalling across grain tissues, but the exact mechanisms remain unclear. Part of the reason for this knowledge gap is that testing our predictions is tricky: grain is a mix of these tissues and regulatory factors act both early and late, complicating and confounding accurate assessments of tissue and time-specific events and their effects on grain. We propose to surmount these challenges by applying two leading-edge technologies in barley. First, we will use single cell RNA sequencing to measure gene expression within individual cells followed by computational clustering to build cell populations and analysis of how these change throughout grain development. Second, we will apply new inducible expression systems to change the activity of regulatory factors at specific times to tease apart the importance of early versus late functions on grain parameters. We will also combine these approaches to assess the influence of regulatory factors activated in specific tissues on the gene expression in neighbouring and distant tissues. Finally, we will explore how these cell populations differ between wild and cultivated barleys and test the functional relevance of wild and cultivated regulatory factors to grain parameters. Taken together, our work will define the developmental trajectories of grain tissues and their responses to regulatory factors controlling maternal versus filial growth and survival, significantly advancing our understanding of cereal grain development.