Controlling seed coat plasticity for seed quality in industry

欧洲种子市场每年价值约50亿英镑。种子质量概括了市场上出售的种子的理想特征：它们应该在广泛的发芽条件下迅速而均匀地发芽，从而在最短的时间内形成均匀的健壮幼苗。这些幼苗应该能长成茂盛的作物林。种子公司在全球多个地点生产杂交种子，每个地点之间和内部的环境变化都可能对种子质量产生负面影响。在所有物种中，种子生产过程中的温度变化是种子质量变化的主要驱动因素，因此在一系列生产环境中培育具有强大种子质量的新品种是种子公司的关键战略目标。我们研究的核心目标是了解种子生产过程中环境变化影响种子质量性状（如休眠、发芽和建立活力）的信号通路。根据我们最近发表的研究和初步数据，我们表明种子生产过程中的温度通过在母体植物中运行的信号通路对种子行为产生重大影响。这是一个重大的新发现，因为以前人们并不清楚是发育中的种子本身感知环境，还是母体植物感知环境并以某种方式将信息传递给后代种子。我们发现，众所周知的调节对冷冻耐受性的冷感应途径也控制着已知与种子行为变化有关的种皮的基因表达和物理特性。该提案的第一部分旨在了解温度传感如何导致种皮的塑性发育，生物化学和渗透性，以及种皮特性如何控制种子行为。本文的主要重点是了解从营养组织实验中已知的冷驯化途径和苯丙素途径基因表达的控制元素如何在母体种皮组织中运作，以及它们在种子中靶点的性质。这需要整合遗传、分子信号和种皮次生代谢转录控制方面的知识。第二个关键部分是将这种新知识从模型转移到作物物种，为此我们与先正达合作评估和提高芸苔属植物的种子质量，这种植物的种子发芽和幼苗建立根据种子生产地点和季节而变化。我们将研究一组具有不同种子质量对成熟环境条件响应的芸苔品种的种子质量控制，并将这些与基因表达和种皮的发育、物理和生化特性联系起来。最后，我们将删除我们在拟南芥中发现的控制影响种子质量的温度信号转导的基因。这里的目标是评估该技术在种子公司产品开发中的应用，与先正达的合作将确保对商业有用的种质资源的开发。我们的新种子技术的一个关键特点是，出售种子的种子质量可以从母株的基因组而不是合子的杂交种子中控制。这意味着出售的种子和作物种子的特性可以独立控制：在未来，当作物的高发芽倾向不受欢迎时，这将在许多情况下有用，例如控制谷物的发芽，温室作物的果实质量。

The European seed market is worth around £5 billion annually. Seed quality summarises the desirable characteristics of seeds sold on the market: they should germinate swiftly and evenly across a broad range of germination conditions, leading to a homogeneous stand of robust seedlings in the minimum length of time. These seedlings should establish a vigourous crop stand. Seed companies produce hybrid seeds in multiple sites globally, each subject to environmental variation between and within sites that can negatively impact seed quality. Across all species temperature variation during seed production is a major driver of variable seed quality, and breeding new varieties with robust seed quality in a range of production environments in now a key strategic goal of seed companies. A core goal of our research is to understand signalling pathways through which environmental variation during seed production affects seed quality traits, such as dormancy, germination and establishment vigour.Based on our recently published research and preliminary data we show that temperature during seed production has a major affect on seed behaviour through a signalling pathway that operates in the mother plant. This is a major new discovery as previously it has not been clear whether the developing seed itself is sensing the environment, or whether the mother plant senses the environment and somehow passes this information to the progeny seeds. We identify that the well known cold-sensing pathway that regulates tolerance to freezing also controls gene expression and physical properties of the seed coat that are known to be linked to changes in seed behaviour. The first part of the proposal aims to understand how temperature sensing leads to the plastic development, biochemistry and permeability of the seed coat, and how seed coat properties control seed behaviour. A major focus here is to understand how elements of the cold acclimation pathway and control of phenylpropanoid pathway gene expression known from experiments in vegetative tissues operate in maternal seed coat tissues and the nature of their targets in seeds. This requires intergrating knowledge from genetics molecular signalling and transcriptional control of secondary metabolism in seed coats.The second key section is to transfer this new knowledge from model to crop species, and for this we have developed a collaboration with Syngenta to assess and improve Brassica seed quality, a species where germination and establishment of seedlings varies according to seed production sites and seasons. We will examine control of seed quality in a panel of Brassica varieties with varying seed quality responses to maturation environmental conditions, and relate these to gene expression and the developmental, physical and biochemical properties of the seed coat. Finally we will delete genes in Brassica that we have shown control the transduction of temperature signals affecting seed quality in Arabidopsis. The goal here is to evaluate this technology for use in product development in seed companies, and collaboration with Syngenta will ensure exploitation of commercially useful germplasm.A key feature of our new seed technology is that seed quality of seed for sale can be controlled in hybrid seed from the genome of the mother plant rather than the zygote. This means that the properties of the seed sold and the crop seed can be independently controlled: in the future this will be useful in the many instances when high germination propensity of the crop is undesirable, such as to control sprouting in cereals, of fruit quality in glasshouse crops.