Stratagem to Tackle Damaging Pathogen Harming Farming Fungal pathogens represent a significant threat to global food crops, reducing yields and adversely affecting quality. A deeper understanding of the mechanisms by which pathogens are able to infect their plant hosts will help lay the foundations for improved control strategies, as Dr Angela Feechan and Dr Anna Tiley explain The fungal pathogen, Zymoseptoria tritici causes Septoria Leaf Blotch, one of the major diseases of wheat across the world, which both adversely affects crop quality and reduces yields. On recognising the presence of a pathogen, plants respond with a nitric oxide (NO) burst which has antimicrobial effects, yet the effects on the attacking pathogen are not fully understood, an area that forms a core focus for researchers in the NO Crop Pathogen project. “The NO burst is a way in which the plant can defend itself against the fungus. Our theory is that maybe the NO burst is released by the plant, and then that might interact with proteins that the fungus releases to try and infect the plant,” outlines Dr Anna Tiley, a post-doctoral researcher working on the project. These proteins effectively help the fungus to invade the host; researchers are investigating how the NO burst interacts with these proteins. “We believe the NO burst might interact with these proteins and de-activate them, but this is still debated,” explains Dr Tiley.
NO Crop Pathogen How does Nitric Oxide (NO) regulate crop pathogen virulence? Dr Angela Feechan School Of Agriculture and Food Science Belfield, Dublin 4 T: +353 1 7167779 E: angela.feechan@ucd.ie W: http://www.ucd.ie/research/people/ schoolofagriculturefoodscience/ drangelafeechan/
Dr Angela Feechan moved to University College Dublin in 2013. She was awarded a Marie SkłodowskaCurie Career Integration Grant in 2014 and a Science Foundation Ireland Career Development Award in 2016. Her group is focussed on fungal pathogens that cause disease in cereal crops particularly, Zymoseptoria tritici, which causes Septoria tritici Blotch (STB) in wheat. Prior to a research scientist position at CSIRO Australia, she completed a post-doc at the University of Copenhagen and PhD at The University of Edinburgh. Dr Anna Tiley is a Post-Doctoral Researcher at University College Dublin, and completed her PhD on Zymoseptoria tritici at the University of Bristol in 2016.
Nitric oxide burst The NO burst itself has attracted a lot of research attention, and it is known to play an important role in a plant’s immune system, yet its impact on a pathogen has not been fully established. This is a topic that researchers in the project are investigating. “We’re particularly interested in fungal pathogens. How does that NO burst impact on their ability to infect? How does the NO that the plant produces impact on proteins that were secreted from the pathogen? How does the pathogen deal with that NO onslaught?” says Dr Angela Feechan, the project’s Principal Investigator. This research is largely laboratory-based, with Dr Feechan and her colleagues in the project looking to identify the proteins that are secreted during infection and understand their impact.
“We’re trying to see whether Zymoseptoria tritici has a specific version of the enzyme, GSNOR and whether this might help it to defend itself from the NO burst that comes from the plant during infection,” outlines Dr Tiley. Researchers are looking to delete the GSNOR gene in this specific pathogen. “We previously did some bioinformatic analysis, looking at the genes encoding this enzyme in other species. We used other sequences of the known GSNOR gene, then aligned that with the Zymoseptoria tritici genome to identify potential candidates,” says Dr Tiley. This work holds broader relevance in terms of potentially protecting crops from infection and preventing fungal diseases. While this is not an immediate prospect, Dr Feechan says the project’s research could help contribute to the wider goal of improving
We’re particularly interested in fungal pathogens. How does that nitric oxide burst impact on their ability to infect? How does the NO that the plant produces impact on proteins that were secreted from the pathogen? The pathogen may have its own enzymes to try and turn over the NO that’s being directed at it, another topic of interest to Dr Feechan. “We’re also trying to characterise one of these enzymes in the pathogen, that might play a role in regulating the NO,” she explains. This particular enzyme is S-Nitrosogluthathione reductase (GSNOR), an enzyme that’s highly conserved in different species and can be used to control NO.
food security in future. “If you knew which proteins were important for disease, you could design strategies to try and target them,” she explains. The project’s research is largely exploratory in nature however, and Dr Feechan plans to continue her work in this area in future. “We’d like to find out more about these fungal proteins, particularly in terms of what proteins they interact with in the plant,” she continues. Diagram summarising function of GSNOR in S-nitrosylation of proteins.
Wheat leaves infected with Zymoseptoria tritici (a) (left) healthy control leaf (right) infected leaf showing symptoms of necrosis (arrow); (b) magnified image of infected leaf showing Z. tritici asexual fruiting bodies (arrow); (c) magnification of curved asexual spores (pycnidiospores) stained with lactophenol cotton blue.
Wheat field trials at UCD Lyons Research Farm, Lyons Estate, Celbridge, Naas, Co. Kildare, W23 ENY.
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