New findings could help protect crops from disease

Discovery of how plants detect pathogens could be a major boost for agriculture

The experimental set up on I04, one of five macromolecular crystallography beamlines at Diamond
© Diamond Light Source 
 
  
An international team of scientists have used Diamond to uncover the mystery of exactly how plants fight off various pathogens. The research could be used to help enhance the ability of crops to defend themselves against disease, thus improving reliability and yield for farmers all around the world.
 
Since the mid-20th century, scientists have had some understanding of how certain varieties of plants fight off some pathogens but not others. Seventy years ago, an American scientist named Harold Flor proposed a model called the “gene-for-gene” hypothesis, which suggests that plants producing a particular gene are resistant to pathogens containing the corresponding gene – this genetic match determines whether or not plants are susceptible to infection by particular viruses, parasites, and bacteria.
 
However as Professor Banfield from the John Innes Centre (UK) observes: “We know that plants have sensors to detect pathogens but we knew little about how they work. But once we understand how these plant sensors detect invading pathogens, we can devise strategies to ‘boost’ the plant immune system and help protect rice and other important food crops from disease.”


And so this study takes Flor’s hypothesis much further, confirming the theory though experiments and providing an unprecedented level of detail on the process by which plants fight off disease at the molecular level. Published in eLife, the research looks at the activity of proteins in rice and their interaction with a fungal infection called ‘rice blast’ that causes devastating disease in rice crops. The group discovered how a specific sensor protein called Pik binds with another protein called AVR-Pik inside rice blast fungus, thus producing resistance to the disease. 

The team led by Professor Mark Banfield, in collaboration with the Iwate Biotechnology Research Centre (Japan) and The Sainsbury Laboratory (UK), used X-ray crystallography facilities on Diamond’s I04 beamline. One of five macromolecular crystallography beamlines at Diamond, I04 provides high resolution imaging, capturing data in under 2 minutes, and produces a beam of synchrotron light as small as 5 micrometres: that’s about the width of a human hair. Using the cutting-edge capabilities on I04, the team succeeded in revealing the interactions between the plant and pathogen proteins at the molecular level, producing an atomic map of the process; this is the first time this has been done for a pair of plant and pathogen proteins that follow the gene-for-gene model proposed by Harold Flor.
 
The team went on to discover that the strength at which the Pik sensor binds the pathogen AVR-Pik protein correlates with the strength of the plant’s response. This means that the plants resistance can be increased by enhancing the binding between the two proteins. This finding opens up new avenues for engineering better plant responses against pathogens by building sensors with increased strength of binding to pathogen proteins – potentially leading to disease-resistant crops.


Dr Abbas Maqbool (John Innes Centre) was first author of the study. He comments: “Harold Flor predicted that plant sensors discriminate between different pathogen types, but at the time he had no knowledge of the molecules involved. It is remarkable that his ideas have now crystallised into detailed molecular models.”

Dr Dave Hall is Principal Beamline Scientist on I04. Observing the global impact of these findings, he comments: “This work highlights the real potential of advanced synchrotron technology to impact on the world around us. Understanding processes at the molecular level allows us to manipulate minute interactions and overcome age old problems. These findings could be hugely important for agriculture, improving the lives and livelihoods of farmers around the world, and it all starts with our ability to see things invisible to the human eye in exquisite detail.”
 
Our enhanced understanding of plant/pathogen interactions at the atomic and molecular level will now allow plant scientists to design solutions to overcome some of the problems associated with disease in crops
To read the paper in full, click here, and to find out more about this research from the John Innes Centre, click here.
 
 
 

 

This project was supported by funding from the Biotechnology and Biological Science Research Council (UK), the European Research Council, the Ministry of Education, Culture, Sports, Science and Technology (Japan) and the Japanese Society for the Promotion of Science.