Researchers at the John Innes Centre have discovered that the capacity of bacteria to spread disease in plants is more extensive than known before.
Using Pseudomonas syringae, they found that the toxin syringomycin affects both flowering and non-flowering plants, indicating a broad potential for this pathogen to infect diverse plant species.
Bacterial Disease Spread in Plants
Bacteria may be capable of spreading disease across a wider range of plant species than previously thought, according to new research.
Scientists at the John Innes Centre used an evolutionary approach to study the diversity of Pseudomonas syringae, a plant pathogen known for infecting various crops, to explore how it targets distantly related plant species.
Pathogen Effects on Non-flowering Plants
Dr. Phil Carella’s research team focused on the bacterial toxin syringomycin, produced by highly infectious P. syringae strains, and tested its effects on both flowering and non-flowering plants.
The experiments revealed that syringomycin was highly toxic to non-flowering plants, represented by liverwort and fern species, causing tissue damage and triggering stress-related gene activity.
These effects were even more important for infections in non-flowering plants compared to flowering plants, which was surprising as much of our current understanding of how pathogenic (disease-causing) bacteria manipulate plant hosts is centered on flowering plants which include some of our major crops.
By featuring non-flowering species, this study, which was published today (December 19) in Cell Host & Microbe, adds to a growing body of research that shows how bacterial pathogens carry the potential to colonize distantly related plants.
“Each of the plant species used in this study has a different life history since they last shared a common ancestor 500 million years ago. However, a single group of pathogens can infect each of them using a common set of pathogenicity factors,” said Dr. Carella.
General Virulence Across Plant Species
“Our results demonstrate that pathogen virulence may be more general across plants than previously believed,” he added.
The researchers hypothesize that P. syringae virulence is centered on fundamental processes shared amongst the Plant Kingdom. In this case, the toxin syringomycin likely interferes with cell membranes across each of the diverse plants tested.
Sometimes non-flowering plants are considered less sophisticated than their flowering relatives which arrived later in evolutionary history, but this study emphasizes the importance of analyzing the whole of the plant world to understand fundamental mechanisms and processes which could be applied to defending food crops against disease.
Implications for Agricultural Research
“Overall, our research shows that diverse plants can reveal useful knowledge about plant-pathogen interactions in general, which is informative for research on crop diseases. We don’t eat liverworts, but they can teach us a lot about the core virulence mechanisms of important pathogens,” observes Dr. Carella.
The next step for this research is to explore the role the toxin plays in promoting the spread of bacteria, and how it cooperates with bacterial effector proteins to cause disease.
Another interesting research question to explore is why some P. syringae populations do not carry the toxin.
The group will also expand the diversity of plants used in the experiments to search for those that are resistant to bacterial pathogens.
Reference: “A necrotizing toxin enables Pseudomonas syringae infection across evolutionarily divergent plants” by Kristina Grenz, Khong-Sam Chia, Emma K. Turley, Alexa S. Tyszka, Rebecca E. Atkinson, Jacob Reeves, Martin Vickers, Martin Rejzek, Joseph F. Walker and Philip Carella, 19 December 2024, Cell Host & Microbe.
DOI: 10.1016/j.chom.2024.11.014
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