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Skip to 0 minutes and 10 seconds In this step, I’m outside on the University of Reading campus with Professor Rob Jackson to discuss his research on how bacteria interact with plants. Hi Rob, how are you? Good. Good to see you again, Glyn, next to our favourite horse chestnut tree. It’s got an infection in the trunk. And this is a bacterium that’s got in there, it’s one of the trees we’ve been working on for many years. How do you actually know that this tree is diseased? Well, on this particular tree we can see a symptom on this branch over here where we can see this kind of ooze coming out of the tree.

Skip to 0 minutes and 42 seconds What’s happened there is that we have these bacteria that are infected into the inside of the tree, and they get inside the vascular system. That’s the system that’s basically transporting liquids. Then it spreads through the tree. They can go all the way through the trunk, into the branches and as the bacteria get all the juicy nutrients from the tree, it’s essentially then growing and replicating. As it does that, these bacteria grow in enormous quantities. And then eventually, they’ll rupture out of the tree and we can see the symptoms as this kind of bleeding. This particular bacterium is very interesting, because it can be blown into the atmosphere and transported by wind over a great distance.

Skip to 1 minute and 25 seconds So it has this really unique property where it can cause water to freeze at a higher temperature than normal. So it actually causes rain to happen in the atmosphere. And then the bacteria get rained back down to earth all over the place. So it’s an amazing mechanism for spreading outside of its local environment. What’s the benefit for the actual organism that kills these trees? Well, of course, what it’s trying to do is get nutrients off the plant, so it can replicate. It’s just like any organism. It wants food. It wants to grow and reproduce. And then they want to disperse and be moved around the environment.

Skip to 2 minutes and 1 second And so this is one of the mechanisms that they use in order to do that. Are there any ways that we can stop this or prevent it from happening? Well, there are many different approaches to try and do that. One is to try and breed plants, to try and have genetic resistance or physiological resistance of some description in order to try and stop infections happening or to very quickly shut down infections. Of course, that would be very hard to do with something like a tree, very difficult, because they’re so slow growing. They’re very hard to work with. There are other ways we can do things.

Skip to 2 minutes and 36 seconds We can apply things like microbes, beneficial microbes into the root systems to try and improve plant growth, improve the vigour of the plant, so it becomes more healthy. One of the really interesting ways actually for a plant like this in particular is to think about using viruses. So there is a typical type of virus called a bacteriophage. And bacteriophages infect bacteria. So this tree is infected with a bacterium called pseudomonas syringae, and there is a bacteriophage, a virus that infects into that bacterium. When it gets inside it, the virus replicates quickly and blows the cell up.

Skip to 3 minutes and 12 seconds So, of course, if you’ve got millions of bacteria in here, if you apply billions of viruses, they can all attack those millions of bacteria, try and kill them off, and that hopefully will be enough just to let the tree’s immune system pick up and then fight off that infection. If we don’t understand how disease works, then we can’t then try and treat it. And so what we need to do is to understand the biology of a lot of these microbes, whether it’s kind of a pathogen or a beneficial microbe, study them, use things like genetics and genomics, cutting edge techniques to understand how they function.

Skip to 3 minutes and 51 seconds Then, we can then try and work out how they interact, and then we can try and use innovative ideas to try and cure disease or even stop disease happening in the first place. Well, thank you for your time, and it’s great being out with you today with our favourite tree. Indeed, yes. Looking a lot healthier that last time I saw it, so hopefully, it’s fighting back and killing off those little pesky pathogens. Thank you.

Meet Professor Rob Jackson

In this second of our ‘Meet the expert videos’, I am joined by Professor Rob Jackson on the University of Reading campus. Rob and I discuss a bacteria that causes bleeding canker disease in horse chestnut trees.

SEM image of rod-shaped Pseudomonas syringae

Close up of SEM image of Pseudomonas syringae

Figure 1: Scanning electron microscope (SEM) images of Pseudomonas syringae, the species of bacteria that Rob discusses in his video. © Professor Rob Jackson

Rob mentions that certain bacteria can trigger rainfall, how do you think they manage to do this? Once you’ve shared your thoughts in the comment area below, take a look at Phys.org website or the Popular mechanics website for the answer.

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Small and Mighty: Introduction to Microbiology

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