An effector-detector domain in a rice immune receptor: towards structure-guided design of new disease resistance proteins.

点击翻译按钮获取中文摘要

Every growing season, significant losses are realised to many of the world's most important crop harvests because of diseases caused by pathogenic micro-organisms, such as fungi, oomycetes and bacteria. This is against the backdrop of increasing demand for food, which continues to rise as the world's population grows and there are changes in diets. Many scientific resources, from traditional plant breeding to chemical control (e.g. fungicides/pesticides), are available to help limit the impact of pathogens on crop yield. However, many of these approaches may have only short-term effects or are environmentally unsustainable. New ways to control plant diseases are required. One way to develop novel control strategies is by understanding the intricate mechanisms of how pathogens cause disease or evade detection by the plant immune system. By understanding these processes we can develop ways to engineer plants to help them fight infection.One mechanism used by plants to fight infection is to detect pathogen agents that are attempting alter plant cells for the benefit of the pathogen. These agents, known as "effectors", give away the presence of the pathogen and plants have evolved to sense these. This triggers a response by the plant that helps stop the infection spreading. The plant sensors can work by directly contacting the effectors, like a handshake, but the important details of how this actually occurs are not known. The plant has to be very precise about knowing if a pathogen molecule is present, and all it may have to go on is the shape of the "hand" (imagine trying to identify one person in a room of 10,000 only by the shape of their hand). The plant cell will induce death of the cell if it senses the effectors, so it has to get it right. We have been studying the interactions of a set of pathogen effectors from a microorganism (fungus) that produces a devastating disease of rice, a major food crop that many people rely on for calories. We have been able to define the nature of the "handshake" between one of these effectors and a plant sensing protein. This is just a snapshot of the interaction, and we need to understand its implications using biochemistry and biological studies in plants. To do this we will use a number of experimental approaches. Firstly, we will define how strong the handshake is between the pathogen effector and plant sensor. Secondly, we will make small changes to the shape of the molecules and see how this affects the strength of the handshake. We will then investigate some small changes that have happened in these pathogen and plant molecules during evolution in nature, using the picture of the handshake we have determined to help us. We also wish to understand why the pathogen is producing the molecules it does, and we will ask questions about what these molecules are doing. Finally, after we understand the interactions formed by the various handshakes in this system, we will engineer a plant sensor protein that can recognise more than one pathogen molecule - which could give the plant a better chance of fighting off infection. We will also see if we can get this to work in a plant other than rice, to see if our new knowledge can help other crops recognise their pathogens.