Molecular genetics of hormone signaling

我的主要研究兴趣是激素如何调节高等植物的发育反应。通过NSERC发现赠款基金，我将我的实验室的工作重点放在了一些激素的作用上，包括乙烯、赤霉素(GA)，特别是脱落酸(ABA)。然而，最近随着化学遗传学的出现，我们相信可以获得关于有机小分子如何调控植物生长发育的新见解，这是传统分子遗传学方法不可能做到的。为此，我们建立了一个化学遗传学程序来剖析拟南芥种子的萌发。利用基因类型特异性筛选，我们已经鉴定了一系列化学物质，它们的性质与一组名为strigollacone的化合物相似。链内酯类化合物首次被鉴定为寄生杂草的种子萌发刺激剂。寄生杂草被认为是发展中国家最具破坏性的农业因素。仅在非洲，Striga物种就侵扰了多达三分之二的可耕地，并造成了作物产量的巨大损失。寄生植物种子高度休眠，只有当它们感觉到寄主根释放的植物内酯时才发芽。在这一点之后，萌发的幼苗的根渗透到寄主并与寄主发展寄生相互作用。利用我们的模型系统，我们已经能够证明在拟南芥中，Strigolacone作用、ABA/GA信号和光信号之间存在着密切的关系。我们将使用化学、遗传学和分子方法的组合来进一步了解这些关系。利用化学遗传学和拟南芥遗传学相结合的方法鉴定植物内酯类化合物，证明了这项新技术在鉴定与植物生长有关的新分子方面的能力。在NSERC发现赠款计划的资助下，我们将第一次有机会了解寄生虫与宿主相互作用中的链内酯的分子基础。

My main research interests are concerned with how hormones regulate developmental responses in higher plants. Through NSERC Discovery Grant funding I have focused the efforts of my laboratory on the roles of a number of hormones including ethylene, gibberellins (GA) and in particular abscisic acid (ABA). However, recently with the advent of chemical genetics we now believe new insights can be gained on how small organic molecules regulate plant growth and development that were not possible using traditional molecular genetics approaches. To this end, we have established a chemical genetics program to dissect germination in Arabidopsis seeds. Using genotypic specific screens, we have identified a collection of chemicals that have similar properties to a group of compounds called strigolactones. Strigolactones were first identified as seed germination stimulants of parasitic weeds. Parasitic weeds are considered the most damaging agricultural agents in the developing world. In Africa alone, Striga species have infested up to two-thirds of the arable land and cause huge losses in crop yields. Parasitic plant seeds are highly dormant and only germinate when they sense strigolactones that are released by the host root. After this point, the root of the germinating seedling penetrates the host and develops a parasitic interaction with the host. Using our model system we have been able to show there is a close relationship between strigolactone action, ABA/GA signaling and light signaling in Arabidopsis. We will use a combination of chemical, genetics and molecular approaches to further understand these relationships. The identification of strigolactones using a a combined approach of chemical genetics with Arabidopsis genetics demonstrates the power of this new technology to identifying new molecules involved in plant growth. With funding from the NSERC Discovery Grants program we will have an opportunity for the first time to understand the molecular underpinnings of strigolactones in host-parasite interactions.