The physiology of metal-tolerance and metal-stress in plants

植物面临许多环境压力。在我的实验室里，我们研究镉和其他金属所施加的压力。镉自然存在于土壤中，但在世界某些地区，由于工业活动、燃料燃烧或长期使用含有微量镉的农业肥料，镉的浓度有所增加。镉可溶于水，易于生物利用，小剂量有毒。在加拿大的一些作物中，包括大豆和硬粒小麦，可食用部分的镉浓度接近或超过安全食用的限度。因此，迫切需要更好地了解控制植物吸收和积累镉的因素。我们研究植物-金属相互作用的方法将是三管齐下的。一些实验将调查使土壤中的镉更多或更少可供植物吸收的生物和化学因素。其他人将研究镉在植物组织中的分布和化学环境--了解镉的结合位置和结合方式，可以提供有关镉如何解毒和储存在植物中的信息。最后，我们将研究植物对金属胁迫响应的生理和分子生物学。具体来说，我们将研究某些酶的反应，这些酶已知参与（i）可以结合，解毒和储存镉的分子的产生或（ii）植物胁迫反应。通过比较缺乏或过度表达这些酶的植物的镉耐受性，我们可以更好地了解它们在镉耐受性和毒性中的作用。除了提高我们对植物胁迫生理学的认识外，这项研究还将对植物修复（选择最大限度地从土壤中吸收金属的植物）以及农业（例如，农业实践或轻度污染土壤的作物选择）。

Plants face a number of environmental stresses. In my lab, we study the stress imposed by cadmium, among other metals. Cadmium occurs naturally in soils but, in some regions of the world, its concentrations are enriched due to industrial activity, fuel combustion or long-term application of agricultural fertilizers that contain trace amounts of this metal. Cadmium is soluble in water, readily bioavailable and toxic in small doses. In some Canadian crops, including soybean and durum wheat, concentrations of cadmium in the edible parts approach or exceed the limits for safe consumption. Thus, there is a pressing need for a better understanding of the factors that control cadmium uptake and accumulation in plants. Our approach to investigating plant-metal interactions will be three-pronged. Some experiments will investigate the biological and chemical factors that make cadmium in the soil more, or less, available for plant uptake. Others will examine the distribution and chemical environment of cadmium in plant tissues - knowing where, and to what, the cadmium is bound provides information about how cadmium is detoxified and stored within the plant. Lastly, we will study the physiology and molecular biology of the plant response to metal-stress. Specifically, we will study the response of certain enzymes that are known to be involved in either (i) the production of molecules that can bind, detoxify and store cadmium or (ii) the plant stress response. By comparing the cadmium tolerance of plants that lack, or over-express, these enzymes we can better understand their role in cadmium tolerance and toxicity. In addition to improving our knowledge of plant stress physiology, this research will have implications for phytoremediation (choosing plants that maximize uptake of metal from the soil) as well as agriculture (e.g., agricultural practice or crop choice for mildly contaminated soils).