Signalling Sex in Plants: The Role of Peptide Signals and the Cell Wall in Fertilisation

植物中的性别信号：肽信号和细胞壁在受精中的作用

• 批准号: BB/W013754/1
• 负责人: Lisa Megan Smith
• 金额: $ 61.21万
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FW013754%2F1
• 关键词: Signalling; Sex; Plants; Role; Peptide

Plant reproduction underpins seed production and is central to food security, yet our understanding of the molecular process by which ovules (the female gametes) are fertilised by pollen (the male gametes) remains incomplete. Fertilisation involves tightly regulated communication between the gametes to ensure that the pollen tube reaches the ovule and releases the sperm cells at the correct position within the ovule. At the core of this molecular conversation is a group of related receptor kinases which span the cell membrane to detect small molecules outside the cell. Signal detection by these receptors is translated into an appropriate cell response via varied downstream events. We know that this family of receptors binds small proteins (peptides) as external cell signals, however the identity of the peptides that pass between the pollen tube and ovules during pollen tube reception is unknown. Downstream events likely include changes in cell wall composition to allow degeneration of a specialised synergid cell at the entrance of the ovule, and burst of the pollen tube within the ovule, but functional data to support this idea is limited, and the range of cell wall changes unclear.Peptide-receptor-cell wall signalling during pollen tube reception is, thus, poorly understood. We will address a number of questions regarding signalling from the pollen tube to the ovule and vice versa in this project using Arabidopsis: 1) which peptides are perceived by the three receptor kinases at the ovule?; 2) which ovule cell wall composition changes during fertilisation are important and which receptors mediate these changes?; 3) are similar peptide signals passed back to the pollen tube from the ovule?; and 4) do they also result in cell wall composition changes required for fertilisation? These questions lead directly to the objectives of the project.Firstly, we will use an assay for receptor signalling in living ovules and test responses to a panel of synthesised ovule and pollen tube peptides to identify which peptides and receptors interact. Secondly, we will produce an atlas of cell well composition in ovules during pollen tube reception in normal plants and mutants lacking the key ovule receptors. Genetic and biochemical techniques will be used to test the functional significance of the interaction of peptides with the ovule receptors, and importance of the cell wall changes for fertilisation. Thirdly, we will then test if similar peptides signal from the ovule back to pollen tube receptors, and fourthly, what changes are seen in pollen tube cell wall composition during fertilisation, following up with genetic and biochemical characterisation of these functions. We will therefore make a significant advance in our understanding of the fundamental process of plant fertilisation, linking signal transduction to altered cell wall composition, and providing novel insight into how signalling controls gamete responses.Longer term, the agricultural industry will benefit from greater understanding of the mechanism behind plant fertilisation, a process important for all our major crops. Due to evolutionary conservation of this fundamental process, knowledge of how fertilisation occurs in a model plant can inform attempts to improve fertilisation (and yield) in crops. This is particularly relevant in the context of the ongoing climate emergency, with more extreme temperature events affecting fertilisation and thus yield. The knowledge gained will contribute to efforts to breed climate ready crops. Beneficiaries of this project include the scientific community who will gain from expanded understanding of plant signalling, using fertilisation as a tractable model system. A post-doctoral research associate and technician will benefit from training in genetics, biochemistry, and molecular, developmental and cell biology. Finally, by supporting a collaboration with Switzerland, the project will strengthen international ties.

植物繁殖是种子生产的基础，也是粮食安全的核心，但我们对胚珠（雌性配子）被花粉（雄性配子）受精的分子过程的理解仍然不完整。受精涉及配子之间严格调节的通信，以确保花粉管到达胚珠并在胚珠内的正确位置释放精细胞。这种分子对话的核心是一组相关的受体激酶，它们跨越细胞膜检测细胞外的小分子。这些受体的信号检测通过不同的下游事件转化为适当的细胞反应。我们知道这个受体家族结合小蛋白（肽）作为外部细胞信号，然而在花粉管接收期间在花粉管和胚珠之间传递的肽的身份是未知的。下游事件可能包括细胞壁组成的变化，使退化的一个专门的助细胞在胚珠的入口处，和爆裂的花粉管内的胚珠，但功能的数据来支持这一想法是有限的，和细胞壁的变化范围不清楚。我们将在本项目中使用拟南芥来解决一些关于从花粉管到胚珠的信号传递的问题，反之亦然：1）哪些肽被胚珠上的三种受体激酶感知？2)受精过程中胚珠细胞壁组成的哪些变化是重要的，哪些受体介导这些变化？3)类似的肽信号是否从胚珠传递回花粉管？以及4）它们是否也导致受精所需的细胞壁组成的变化？这些问题直接导致了该项目的目标。首先，我们将使用活胚珠中受体信号传导的测定，并测试对一组合成的胚珠和花粉管肽的反应，以确定哪些肽和受体相互作用。其次，我们将制作一个正常植物和缺乏关键胚珠受体的突变体在花粉管接受过程中胚珠中细胞孔组成的图谱。遗传和生物化学技术将用于测试肽与胚珠受体相互作用的功能意义，以及细胞壁变化对受精的重要性。第三，我们将测试类似的肽是否从胚珠返回到花粉管受体，以及受精过程中花粉管细胞壁组成的变化，以及这些功能的遗传和生化特征。因此，我们将在我们对植物受精的基本过程的理解方面取得重大进展，将信号转导与细胞壁组成的改变联系起来，并为信号转导如何控制配子反应提供新的见解。长期而言，农业产业将受益于对植物受精背后机制的更深入理解，这一过程对我们所有的主要作物都很重要。由于这一基本过程的进化保守性，关于模式植物中受精过程的知识可以为改善作物受精（和产量）的尝试提供信息。这在当前气候紧急情况下尤其重要，因为更多的极端温度事件影响施肥，从而影响产量。所获得的知识将有助于培育适应气候的作物。该项目的受益者包括科学界，他们将利用施肥作为一个易于处理的模型系统，从扩大对植物信号的理解中获益。博士后研究助理和技术员将受益于遗传学，生物化学，分子，发育和细胞生物学的培训。最后，通过支持与瑞士的合作，该项目将加强国际联系。