Uncovering the mechanisms of plant cell wall signalling and responses

植物细胞壁包围和保护所有的植物细胞。对于植物和地球上77亿人的日常生活来说，它是必不可少的。细胞壁为我们提供了水果、蔬菜和谷物中的膳食纤维；然而，人们越来越担心，目前的粮食生产率可能无法满足未来的需求。木材和其他干燥的细胞壁材料传统上是作为一种能源燃烧的；今天，人们对将植物生物质用作下一代可再生生物燃料的兴趣继续增强，例如从发酵的细胞壁材料中提取的生物乙醇。细胞壁也为环保和可再生材料提供了令人兴奋的资源；自从加拿大政府宣布将从2021年开始禁止许多一次性塑料以来，公司正在寻找生物塑料，这种塑料通常来自细胞壁材料。植物生物学和生物技术在解决这些紧迫的经济和环境问题方面具有极大的潜力。特别是，无论是通过传统育种还是通过基因改造，植物细胞壁都是一个重要的改良目标。然而，先前改变植物细胞壁的尝试暴露了我们在理解上的一个关键差距：植物通过基本不为人所知的机制来感知细胞壁的状态，这种机制被称为“细胞壁信号”，而植物对这些信号的典型反应是限制生长。因此，细胞壁的修饰通常会导致产量损失，从而使任何细胞壁的“改良”在农业和经济上都是不可行的。麦克法兰实验室的长期目标是发现植物如何感知细胞壁的变化并做出反应。这项建议利用我们之前生成的大规模数据集来发现细胞壁信号的新组件。我们将结合植物遗传学、分子生物学、生物化学、定量活细胞成像、高分辨率电子显微镜和对这些数据集的计算分析，来表征这些细胞壁信号成分的分子机制，并追踪植物对这些信号的反应。这项工作提出了一些关键问题，例如：细胞壁信号需要哪些分子成分？细胞壁信号是如何“开启”或“关闭”的？不同的细胞壁变化会激活相同的信号吗？植物是如何对这些信号做出反应的呢？在植物做出反应之前，我们可以对细胞壁进行多少修改？细胞壁信号是否影响其他植物信号通路，如免疫反应或激素信号？通过解决这些问题，我们将培养下一代在加拿大接受培训的科学家，并扩大关于细胞壁信号转导的基础知识。这项研究的结果将为如何最好地提高植物生产力以应对加拿大当前和未来的挑战提供洞察力，例如推进可持续农业、增强粮食安全以及开发下一代生物燃料和生物材料。

The plant cell wall surrounds and protects all plant cells. It is essential to everyday life for plants and for all ~7.7 billion people on Earth. Cell walls provide us with dietary fibre in the fruits, vegetables, and grains that we eat; yet there are increasing concerns that current food production rates might not meet future demands. Wood and other dried cell wall material is traditionally burned as a source of energy; today, interest continues to intensify in using plant biomass as a source for next-generation renewable biofuels, such as bioethanol derived from fermenting cell wall material. Cell walls also offer an exciting resource for environmentally-friendly and renewable materials; since the Canadian government's announcement that they will ban many single-use plastics starting in 2021, companies are looking to bio-plastics, which are often derived from cell wall material. Plant biology and biotechnology have excellent potential to address these pressing economic and environmental issues. In particular, the plant cell wall is an important target for improvement, either by traditional breeding or genetic modification. However, previous attempts to modify plant cell walls have exposed a critical gap in our understanding: plants perceive the status of the cell wall via largely unknown mechanisms, called "cell wall signaling" and the typical plant response to these signals is to limit growth. Therefore, cell wall modifications often cause yield penalties that render any cell wall "improvements" agriculturally and economically unviable. The long-term goal of the McFarlane lab is to discover how plants sense and respond to cell wall changes. This proposal leverages large-scale datasets that we previously generated to uncover new components of cell wall signaling. We will characterize the molecular mechanisms of these cell wall signaling components and track plant responses to these signals using a combination of plant genetics, molecular biology, biochemistry, quantitative live cell imaging, high-resolution electron microscopy, and computational analyses of these datasets. This work asks key questions, such as: What molecular components are required for cell wall signaling? How is cell wall signaling turned "on" or "off"? Do different cell wall changes activate the same signals? How do plants modify their cell walls in response to these signals? How much can we modify the cell wall before the plant responds? Does cell wall signaling affect other plant signaling pathways, such as immune responses or hormone signaling? By addressing these questions, we will develop the next generation of Canadian-trained scientists and expand foundational knowledge about cell wall signaling. Results from this research will provide insight into how best to improve plant productivity to address current and future challenges in Canada, such as advancing sustainable agriculture, enhancing food security, and developing next-generation biofuels and biomaterials.