Decoy

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Decoy

Pathogens, we rather not have them. But keeping them away or getting rid of them is not always that easy. Sometimes they take essential processes hostage. Processes which a plant can’t do without. This makes the ideal for pathogens to use them for their own growth. Still plants are not that easily to infect. They can even defend themselves against hostage taking pathogens. By using a decoy, so discovered British and German researchers.

The researchers discovered this decoy while analysing what it is that makes some Brassica crops, like oilseed mustard, resistant against white blister rust. Two genes, CSA1 and CHS3, it turns out. When these genes are present then after infection a rapid immune response, in the form of cell death, follows. The researchers noticed that CHS3 looked like a group of proteins (DA1 and DAR) which are needed for the development of plant organs, like new leaves. This, lead to the question how CSA1 and CHS3 cause white blister rust resistance.

The first hint that the researchers got that CHS3 could be a decoy was when the substituted the CHS3 domain that was comparable with that of DA1 and DAR proteins with the comparable DA1 or DAR domain. The researchers noticed that DA1 and DAR domains that were most similar to the comparable CHS3 domain, could substitute this domain.

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Through functioning as a decoy, CHS3 allows DAR3 to do its job

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DA1 and DAR proteins are needed for proper plant development. But their influence on pathogens is unknown. Therefore, the researchers studied the effect of DA1 and DAR proteins on white blister rust pathogen growth. In the absence of DA1, DAR1, and DAR2 the researchers observed less pathogens. In contrast, when there was more DA1 present, there was also more pathogens.

Leading to the question: What is influencing DA1 activity? To find out the researcher analysed which proteins bind to DA1. They found that DA1 interacted with itself, but also with DAR1, DAR2, and DAR3. But only the interaction with DA1 resulted in a reduced activity of DA1.

Subsequently the researchers studied the effect of DAR3 on pathogens. The researchers observed less white blister rust pathogen growth when DAR3 was present in the presence of CSA1 and CHS3. But in absence of CSA1 and CHS3 the amount of DAR3 proteins was swiftly reduced in white blister rust infected plants.

Through functioning as a decoy, CHS3 allows DAR3 to do its job. In this was CHS3 prevents that white blister rust takes DA1, DAR1, and DAR2 hostage. The plant is preventing infection through setting a trap for pathogens.

Literature

Benguo Gu, Toby Parkes, Fernando Rabanal, Caroline Smith, Fu-Hao Lu, Neil McKenzie, Hui Dong, Detlef Weigel, Jonathan D.G. Jones, Volkan Cevik, and Michael W. Bevan (2023) The integrated LIM-peptidase domain of the CSA1-CHS3/DAR4 paired immune receptor detects changes in DA1 peptidase inhibitors in Arabidopsis. Cell Host & Microbe, https://doi.org/10.1016/j.chom.2023.04.009

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