Molecular mechanisms of dormancy and germination in parasitic and non-parasitic plants

寄生和非寄生植物休眠和发芽的分子机制

• 批准号: RGPIN-2017-06752
• 负责人: Lumba, Shelley
• 金额: $ 2.7万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=686972
• 关键词: Molecular; mechanisms; dormancy; germination; parasitic

One of the major impediments to food security in Africa is infestation caused by a parasitic plant called Striga hermonthica. Striga parasitizes major food crops like sorghum, rice and millet, which results in 30 to 100% yield losses for over 100 million subsistence farmers. As an obligate hemiparasitic plant, Striga cannot survive on its own and relies on infecting a plant host in order to obtain nutrients, water and assimilates. It is essential that Striga seed “wake up” (germinate) and begin growing only when a potential host is nearby. As a result, Striga has evolved unique strategies that are distinct from non-parasitic plants. For example, seeds typically germinate in response to light and plant hormones like gibberellic acid (GA). Striga, however, does not respond to these signals. Instead, Striga seeds wake up upon detecting a class of plant hormones called strigolactones (SL). This chemical signal is released into the soil by plant hosts to promote a beneficial interaction with fungi. Striga's dependence on host-derived SLs is a weakness that can be exploited for the development of technologies to combat Striga infestations. This will require a detailed mechanistic understanding of how Striga seeds use SL as a “wake up” signal in the soil.*** Not surprisingly, there are many signals that affect the seed's decision to germinate. Seeds have to integrate all of this information and translate it into gene expression. Certain combinations of gene expression make up a “germination code” to instruct a seed whether or not to wake up. In many ways, Striga has rewired this germination code because of its dependence on SLs, rather than environmental cues, to trigger germination. The Lumba Lab will determine how Striga has rewired the code by combining cutting-edge approaches such as transcriptomics and large-scale protein interaction studies. During my post-doc, I successfully applied these methods to construct protein interaction networks in Arabidopsis thaliana. Our approach will identify components that are important for germination in Striga and examine how these components interact based on high-throughput yeast two-hybrid methods. My group will apply systems biology approaches to build signalling networks which will reveal how various signals converge to form the germination code. To understand the evolution of the code, we will construct networks of Striga and Arabidopsis components. Comparing these networks will reveal protein interactions that have been gained or lost by Striga, which will provide insight about the evolution of Striga's parasitic lifestyle.******Significance: Despite the devastating effects of Striga on 100 million people, molecular mechanisms underlying germination in parasitic plants are largely unknown. Elucidating these mechanisms, not only will answer fundamental evolutionary questions in biology but also lead to solutions in combating the scourge of Striga.

非洲粮食安全的主要障碍之一是一种名为Striga hermonthica的寄生植物造成的虫害。Striga寄生在高粱、水稻和小米等主要粮食作物上，导致超过1亿自给农民的产量损失30%至100%。独脚金属植物是专性半寄生植物，不能独立生存，需要通过感染植物宿主来获取营养、水分和同化物。只有当潜在的宿主在附近时，独脚金种子才会“醒来”（发芽）并开始生长。因此，独脚金进化出了不同于非寄生植物的独特策略。例如，种子通常会响应于光和植物激素如赤霉酸（GA）而发芽。然而，Striga对这些信号没有反应。相反，独脚金种子在检测到一类称为独脚金内酯（SL）的植物激素时醒来。这种化学信号被植物宿主释放到土壤中，以促进与真菌的有益相互作用。Striga对宿主来源SL的依赖是一个弱点，可以利用它来开发对抗Striga侵扰的技术。这将需要对独脚金种子如何使用SL作为土壤中的“唤醒”信号进行详细的机械理解。*** 毫不奇怪，有许多信号影响种子发芽的决定。种子必须整合所有这些信息并将其转化为基因表达。基因表达的某些组合组成了一个“发芽密码”，以指示种子是否醒来。在许多方面，Striga已经重新连接了这个发芽代码，因为它依赖于SL，而不是环境线索，以触发发芽。Lumba实验室将确定Striga如何通过结合转录组学和大规模蛋白质相互作用研究等尖端方法来重新连接代码。在我的博士后期间，我成功地应用这些方法构建了拟南芥蛋白质相互作用网络。我们的方法将确定在独脚金中发芽的重要组成部分，并研究这些组成部分如何基于高通量酵母双杂交方法相互作用。我的团队将应用系统生物学方法来构建信号网络，这将揭示各种信号如何汇聚形成萌发代码。为了理解编码的进化，我们将构建独脚金和拟南芥组分的网络。比较这些网络将揭示Striga获得或失去的蛋白质相互作用，这将提供有关Striga寄生生活方式进化的见解。重要性：尽管Striga对1亿人造成了毁灭性的影响，但寄生植物发芽的分子机制在很大程度上是未知的。阐明这些机制，不仅将回答生物学中的基本进化问题，而且还将为打击Striga祸害提供解决方案。