The Rhizosphere Zone: Focusing on the Importance of Plant Health in the Lab

Richard Jacobs: Hello, this is Richard Jacobs with the Finding Genius podcast. As usual, I’m looking for the top performers in their fields. The scientists, clinicians, engineers, et cetera. That’s a really going above and beyond and learning what’s not commonly known. So today I have Ayanna Jones. She is a graduate student at Emory University. We will be talking about the dynamics of the rhizosphere of plants, bacteria and climate change. So Ayanna, thanks for coming.

Ayanna Jones: Thank you for having me.

Richard Jacobs: What is the rhizosphere? For people that don’t know?

Ayanna Jones: Yeah. So rhizosphere is a complex zone of soil surrounding plant roots with various interactions between plants, bacteria and other microorganisms.

Richard Jacobs: Yeah, I’ve heard that bacteria I guess will form in I guess plant created structures or maybe bacteria created structures called nodules. On the roots like what is the rhizosphere look like if you pull the plants out of the ground and looked, what would you see?

Ayanna Jones: Yeah, so really, once you pull the plant out of the ground, you really going to be looking at the roots and the rhizosphere is like a coding. If you can imagine a very thin coding that’s kind of invisible to the human eye but it’s just whatever coats the roots of plants. And so this zone is very unique because many complex interactions are occurring and we want to say the rhizosphere because can give us a lot of insight into plant dynamics as well as the unique chemistry of the plant and its surroundings.

Richard Jacobs: Well, what’s the rhizosphere composed of? what’s in it and how it’s happening?

Ayanna Jones: Yeah, so the rhizosphere is mostly composed of microorganisms and various other channels if you will, where these microorganisms can move throughout and really kind of either assist with wounding processes or if a plant gets wounded just like humans it has its own unique mechanism in which microorganisms will come around and try to repair the plant if it can. And so other channels within the rhizosphere will allow the plant to uptake water and interact with other nutrients that may be in the soil. So this is really kind of like a cellular membrane, if you will, where the plant can communicate with the outside environment.

Richard Jacobs: So what is the plant able to do with its root structure? What is it not able to do that the rhizosphere does for it? Has that been teased apart and figured out?

Ayanna Jones: Yeah. So this is actually getting into what we are examining with our own research. The rhizosphere really allows and there are other ways that micro or microorganisms can interact with the plant, but specifically the rhizosphere is unique because it is such a complex zone. And ultimately the rhizosphere is useful because it allows us, particularly in my lab in the group to examine the availability of various nutrients and produced by the plant and how this regulates southerner behavior at wounding versus non wounding sites. And so for our research, this is interesting to us because this could be an analog for understanding other biological processes in how wounding occurs and how we can repair wounding. Not only that, but also it’s a myriad of applications not only biologically but also environmentally in regards to understanding how microorganisms can contribute to climate change and how understanding this unique sphere of the plant can help us with agricultural production and engineering, better products to ultimately increase crop yields and reduce emissions into the atmosphere.

Richard Jacobs: So are you studying how plants get hurt or is it, all these things, like how out of the root system of a plant be hurt?

Ayanna Jones: Yeah. It’s all these things. So mostly we’re looking at the kinetics of wounding and non-wounding sites of plants.

Richard Jacobs: What does that mean? How does a plant get wounded? How does it get hurt? How would this happen out in a field or in nature?

Ayanna Jones: Yeah, for sure. So plants can get wounded different ways. Naturally by age, by physical processes. So if you take, for instance, if you take a piece of grass and you break it, it’s wounded, right? And so naturally this ignites a unique response from the plant. Just how when we get wounded our white blood cells start to go to work and our bodies are trying to prohibit any bacteria or any other type of complications from forming from that wound site. So just as that is happening for us, for plants is the same way. So what we look at is we look at the kinetic models that show the behavior of the bacteria at wound and non-wounding sites on the host and we hope that this will help us determine the availability of oxygen within the rhizosphere specifically the bacteria that we’re looking at migrate towards host cells and express pathogen genes. So we’re really looking at the unique interplay between bacteria and pathogens in the rhizosphere and we use both computational and experimental methods to do so. And so we hope to better understand the kinetics of the chemistry in the rhizosphere because of course, I mean my PhD in chemistry, so it’s still back to chemistry, but we hope to understand this and allow this to give us insight into other plants and allow us to further understand the role that this may have on climate change.

Richard Jacobs: So if you understand what happens when a plant gets wounded, I mean with this mean maybe you can harvest certain crops in a different way so as not to disturb their root systems to the point where they won’t be able to stay there and regrow. Maybe that’s an application or like what would an application be of what you’re learning?

Ayanna Jones: For. Sure. It’s definitely one application. Another application is crop engineering and that kind of what that is as well where you can literally engineer pesticides or engineer other growth aids or other plant aids to prevent any unwanted bacteria or unwanted wounding, if you will, of the plant. Another application, as I mentioned, climate change, we know that as climate change is occurring and as our populations are increasing ultimately there’s a shortage of land. And so it’s important for us to take care of the crops and the land that we have. And so learning how to preserve the crops that we have is very important and it extending the lifetime of those plants and what they can give us is very important. So any type of plants or agricultural engineering can come out of this as well.

Richard Jacobs: Well, you mentioned climate change. Are you studying what happens to the rhizosphere under let’s say a higher carbon dioxide environment or maybe greater soil acidity or like what conditions would model that that you can look at and see the effect?

Ayanna Jones: Yeah, for sure. That’s great. So that is definitely something that we plan on doing in the future. Right now we’re doing the basics of removing any type unwanted variables at the moment. Our goal is to complicate the model, if you will, by adding other variables such as temperature, varying temperatures or varying acidity levels in the soil. Because these are things that must be considered if you’re thinking about various environments from various locations of the world. There are different climates and things. So it’s important to understand those variables and how they can affect our results.

Richard Jacobs: So what are you working on literally right now in your research? What kind of experiments do you have running? What are you trying to figure out?

Ayanna Jones: Yeah, so at the moment I am currently replicating work done by a previous post doc old and what she did is she initially created an analog by using various solvents to mimic what would be happening within the rhizosphere in regards to the pathogens and the parasitic plants. And so I’m currently replicating her work and it’s been very, very fun. It’s my first time actually growing plants in the labs as an experiment. So I’ve been really enjoying that. I’m currently growing sorghum which is a relative to corn actually. I’ve never tasted sorghum, but I’ve heard its okay. But sorghum is actually commonly found in Africa and people have been wanting to learn more about sorghum for various reasons. Africa is a great place to grow crops. And so I think that understanding sorghum can open a window into understanding other types of crops. Similar to sorghum or maybe dissimilar, but using the same methods, we could better understand other crops that we’re growing.

Richard Jacobs: So how do you differentiate between the bacteria that are necessary and commensal and mutualistic with the plant and pathogenic ones, ones that aren’t part of its normal, I guess maybe called microbiome?

Ayanna Jones: Yeah, so the parasitic plants that we’re looking at is the strikas sciatica and the bacteria that we’re studying is for specifically for my experiment, is the rhizobium radiobacter. That’s the full scientific name. So the pathogens in this case rely on semiogenesis and semiogenesis is a carry out a wounding process and the pathogens rely on semiogenesis to generate small molecules through redox. And so that’s basically what’s happening. So we’re looking to see how these two interact and a lot is unknown actually. And so I’m curious to find out more about how the parasitic plants and the bacteria interact and any unique chemistry that comes out of their interaction.

Richard Jacobs: Okay. I mean, what functions in particular do bacteria seem to have when they’re in contact with a root system? Are they, I guess they’re doing the nitrogen fixation. What’s common?

Ayanna Jones: Yeah, so when the bacteria ultimately comes into contact with the plants it is using a unique process. So when a plant is wounded various chemicals are being released. And so our goal still is to learn more about what happens when the bacteria are interacting with the plants. We believe that they are kind of living on the plant and attracted to the chemicals that the plant is releasing as it’s being wounded. But we don’t really yet know what exactly is going on and how they’re benefiting from that. And so hopefully our research will show how they’re using these chemicals and what benefit it is to them.

Richard Jacobs: And are you doing this just for sorghum or for a bunch of plants? Amongst plants there are very different types of root systems and interactions or is it pretty similar across a certain class?

Ayanna Jones: Yeah. So as of now, I’m only looking at the sorghum. There is other literature that people are using other types of plants. Plants typically fall into two main categories. And so we’re sticking to monocots, if you will, more so than which means that we’re sticking to plants that like grass and tobacco. And so ultimately we want to understand that first and in the future we will definitely be interacting at plants of other classes, more complex plants, if you will, that may be larger, but as of now, we’re starting something very small and simple to use, which is sorghum seeds. And I’m currently growing those right now and it’s been really fun. The sorghum seeds are very, very tiny and of course when they grow, they’re larger, but it’s easier to maintain right now for our research. So yeah, and in the field currently, there’s been a lot of interest in what we do, which is systems chemistry. That’s really the overarching category, if you will, of what kind of research we do. And systems chemistry is ultimately just looking at how systems operate over a period of time. And so we look at the rhizosphere as one large organ that is operating over a period of time, obviously that has many interactions and it’s our goals to understand the various interactions that are at play and how this ultimately benefits or does not benefit the rhizosphere.

Richard Jacobs: What about fungi that are there? I’ve heard that they play a very important role as well, not just the bacteria but the fungus also.

Ayanna Jones: Yeah. So I’m not sure actually I assume that fungi or any other type of organism that’s surrounding the rhizosphere will definitely have some impacts. I think that the addition of the fungi varies, has a different impact varying on the plant type or the environment for some plants. And I’m not sure which plants these are. I’m assuming for some plans the fungi could definitely benefit by providing various nutrients or protection from other types of organisms. But for others if the fungi is placed in a system that is a natural to the fungi or the plant, it could harm the planet in various ways. So I think for our research I don’t see fungi being a large part of the system, but it may be in the future as we scale up the types of plants that we’re looking at.

Richard Jacobs: Okay. That makes sense. Well, very good. What’s the best way for people to, maybe get a glimpse into what you’re doing? I don’t know if there’s any papers you put out or just to see what the lab is doing.

Ayanna Jones: Yeah, of course. So right now I’m a first year graduate student, so I have not yet published anything in this just yet. But if people are interested, they should definitely visit our labs website, https://www.lynnlabemory.com/. And there you’ll be able to find more about our group and various literature that we publish on this research and other work that happens in our group.

Richard Jacobs: Okay. Very good. Well, I appreciate you coming and I’m sure there’s a ton going on there that a lot of people have to work on to figure out. So I guess I think people think of plants is really simple things, but I mean, if what I’ve learned, they’re like incredibly complex.

Ayanna Jones: Yeah. I’ve definitely learned that as well. And there’s also other applications that I didn’t mention, the astrobiological component, which understanding systems chemistry in both plant microbiology as well as Ash biology. And so there’s lots of things but you kind of take away different sub fields.

Richard Jacobs: Very good. Thanks for coming on the podcast. I appreciate it.

Ayanna Jones: Thank you.