For the first time, scientists have discovered a single detection system in plants against a large group of bacteria, fungi and oomycetes, including pathogens such as downy mildew and potato blight. These broad group of micro-organisms secrete proteins, one of which can be recognised by the immune system of the model plant Arabidopsis. This serendipitous discovery may make it possible to protect other plants against a wide range of micro-organisms. The discovery was made by plant scientists at Utrecht University, together with their German colleagues. Their findings will be published this week in the academic journals PNAS and PLoS Pathogens.
“Plants have immune receptors on their cell surface that can recognise intruders and defend against them. These immune receptors detect very specific molecules and then activate the immune system. We have now discovered that the model plant Arabidopsis has an immune receptor that can recognise a very wide range of unrelated micro-organisms. That is because they all secrete proteins called NLPs. This is the first time that we have found a molecular similarity in the way the plant immune system is activated by such a diverse group of organisms”, explains Dr. Guido van den Ackerveken from Utrecht University.
Other plants, such as tomato and potato, cannot recognise NLPs. The next step in the research is to trace the NLP immune receptor in Arabidopsis. Then the scientists can test whether it is also active in other plant species, so that it can be used to protect crops against pathogens. This approach has already proven to be successful with another immune receptor that recognises bacterial pathogens.
The hundreds of different NLP proteins that Arabidopsis can recognise are all made up of 200-300 amino acids. A very small part of these NLPs, between nine and 24 amino acids long, is sufficient to cause the immune reaction. This also happens to be the most similar part of these proteins that are secreted by bacteria, fungi and oomycetes.
The researchers discovered this piece of protein, and the immune reaction it provokes, by accident. The researchers were actually studying the role that NLP proteins play in the plant’s disease process. They used the model plant Arabidopsis for this purpose. To their surprise, however, they discovered that the NLP proteins did not make the Arabidopsis more susceptible to disease, but actually caused it to display a strong immune reaction.
Nep1-like proteins from three kingdoms of life act as a microbe-associated molecular pattern in Arabidopsis
Stan Oome*, Tom M. Raaymakers*, Adriana Cabral*, Simon Samwel*, Hannah Böhm, Isabell Albert, Thorsten Nürnberger, and Guido van den Ackerveken*
PNAS, 3 November 2014.
*Affiliated with Utrecht University
The research by the German colleagues, who came upon the same discovery via a different process, will appear later this week in PLoS Pathogens.
A conserved peptide pattern from a widespread microbial virulence factor triggers pattern-induced immunity in Arabidopsis
Hannah Böhm, Isabell Albert, Stan Oome, Tom M. Raaymakers, Guido van denAckerveken, Thorsten Nürnberger
PLoS Pathogens, 6 November 2014
This research was funded in part by the NWO programme ‘Meer met Minder’, the Centre for Biosystems Genomics and the Deutsche Forschungs Gemeinschaft.
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