Elucidating the OXI1 stress signalling network

和我们一样，植物利用由氧气形成的化合物，不是为了呼吸，而是为了一个完全不同的目的。这些高活性化合物被称为“活性氧”（ROS），当白细胞在血液中发现细菌时就会产生。这引发了一系列事件，使血细胞能够杀死细菌，从而防止感染的传播。活性氧本身并不是用来杀死细菌的，而是它们“启动”血细胞中的过程，帮助它杀死细菌。可以理解的是，科学界对这种类型的系统感到非常兴奋，因为对它的理解可以帮助对抗疾病（一些疾病，如类风湿关节炎，是由于关节细胞不能正常发挥这一功能而发生的）。最近发现，ROS的这种使用方式不仅限于人类细胞，事实上植物也利用这种机制。也许不足为奇的是，其中一个例子就是植物本身受到细菌和真菌的攻击。植物没有血细胞，所以它们会产生化学物质来杀死病原体，防止感染的传播。我们感兴趣的是找出从活性氧到用这种方式管理植物疾病的步骤。一种名为ox1的蛋白质被鉴定出来，并被发现参与了其中一个步骤。如果这种蛋白质从植物中移除，它们就不再能够适当地保护自己免受微生物的攻击。人们发现，ox1通过向其他蛋白质添加一种化学“标签”（即磷酸盐）来“标记”它们，从而起作用。这是细胞中常见的伎俩，用于使蛋白质工作或停止工作，即控制其功能。这里提出的研究旨在准确地确定哪些蛋白质ox1“标记”，哪些蛋白质与它结合来发挥作用。通过这种方式，可以发现从活性氧到对抗植物病害的一系列步骤，并利用这些步骤为人类造福，即培育对害虫（如霉病）抵抗力增强的作物。

In common with us, plants utilise chemical compounds formed from oxygen, not for breathing but for an altogether different purpose. These highly-reactive compounds are know as 'reactive oxygen species' (ROS) and are produced for instance when a white blood cell finds a bacterium in the bloodstream. This initiates a series of events which allows the blood cell to kill the bacterium, and thus prevent spread of infection. The ROS are not themselves used to kill the bacterium, rather they 'turn on' processes in the blood cell which help it to kill the bacterium. Understandably there is a lot of excitement in the scientific world regarding this type of system, as an understanding of it could help with combating disease (some diseases such as rheumatoid arthritis occurs when cells in joints do not perform this function correctly). Recently it was found that the use of ROS in this way is not limited to human cells, and in fact plants utilise this mechanism also. Perhaps not surprisingly, one such instance is when plants are themselves attacked by bacteria and fungi. Plants do not have blood cells, so instead, produce chemicals which will kill the pathogen, and prevent spread of infection. We were interested in finding what the steps were leading from ROS to the management of plant disease in this way. A protein, called OXI1, was identified and was found to be involved in one such step. If this protein was removed from plants, they were no longer able to defend themselves properly from microbes attacking them. It was found that OXI1 worked by 'labelling' other proteins by adding a chemical 'tag' to them, namely phosphate. This is a common trick in cells, used to either make a protein work, or to stop in working i.e. to control its function. The research being proposed here seeks to identify exactly which proteins OXI1 'tags' and which ones it binds to do its work. In this way, the series of steps from ROS to combating plant disease can be discovered, and utilised to human benefit i.e. breeding crops with increased resistance to pests e.g. mildew.