Soil Microbes and Crop Resilience with Dr. Amy Grunden

Dr. Amy Grunden, professor of microbiology at NC State University, discusses how soil biology and plant–microbe interactions play a critical role in crop resilience under heat, drought, and other climate stresses. She shares insights into how microbial diversity supports nutrient cycling, disease suppression, and overall plant health, and how interdisciplinary research is deepening our understanding of resilient cropping systems. Find out what these discoveries could mean for growers and the future of climate-ready agriculture on this episode. 

Transcript

Speaker 1:

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Dr. Adrian Percy:

So in this episode of AgTech360's Climate Ready Agriculture series, we're joined by Dr. Amy Grunden, who is a professor of microbiology at NC State University and also the assistant director of the North Carolina Agricultural Research Service. We're going to be exploring how soil biology and plant-microbe interactions shape crop resilience despite heat, drought, and other climate stresses. We'll dig into how interdisciplinary research is advancing our understanding of resilient crops and what these insights could mean for both growers and the future of food systems. So Amy, delighted to have you on the episode. Welcome.

Dr. Amy Grunden:

Well, thank you very much. I'm very pleased to be here and to share what I hope will be some interesting insights with you.

Dr. Adrian Percy:

And I'm sure they will be. So let's talk first about you. Maybe you can give us a little bit of information on your lab, what your focus areas are. But also, how did you get into this line of research, and particularly into agriculture?

Dr. Amy Grunden:

So I am a microbial physiologist. And I use my lens of microbial physiology research to develop microbial technologies for sustainable agriculture and for sustainable environments. And what that means is that I try to understand how microbes work in their environmental context and how we can use microbes, who, by the way, are the best chemists in the world. So the incredible thing about microbes is you can go into any environment and you can find a microbe that will do a chemical process that you want, right? And the power of the microbe is that it's bringing very specific biology to a chemistry so that you can get the products that you want at the end in a very specific way. And the challenge for us as scientists is to understand how we help the microbe do the process we want it to do.

Dr. Adrian Percy:

So let's get into a little bit more about that, and particularly your research. But first, can we kind of zoom out? And I know you're working a lot on resiliency in crops, and we'll talk a little bit about those. But in terms of what is actually happening underground, as it were, when we have maybe extreme conditions of drought and heat, can you describe a little bit about those types of stresses, what that means for the microbial populations in soil, and also for the plants?

Dr. Amy Grunden:

Sure. So first off, I want to start with ... and I think most people have an ... Well, most folks that work with crops have an understanding that there are particular microbes that can help benefit crops as they develop. So these microbes help the plants access the nutrition that they need and can help protect plants from disease and pests, right? Plants have natural associations with microbes, largely through their root systems, but increasingly, we have an understanding that there's also microbial communities associated with leaves and stems of plants, and that these distinct microbial populations are actually working in concert to help the plant develop. Okay? And the work that I'm doing is actually working with a crop, a staple crop that's very important globally, wheat. And we are analyzing the microbiome associated with wheat, both underground and above ground. But getting to your question about how microbial communities, those associated with the plant and those in the soil, shift in response to changes in the environment and sort of writ large extremes in the environment.

Yeah. So when you have conditions of drought or you have very low temperatures or very high temperatures, that does change your microbial populations. And therefore, any microbial populations you're changing in the soil, you're changing the microbes that are available to interact with your plant. So one of the things that we need to have a good understanding of is the fact that microbes are very important to chemical cycling within the soil. So what's happening with nitrogen? What's happening with phosphorus availability that's needed for plant nutrition? And when you do have changes in temperatures, changes in salinity, changes in water availability in soil systems, that definitely changes your microbial populations that potentially are participating in nitrogen cycling or phosphorus cycling or carbon cycling. And all of that impacts plant productivity in the soil.

Dr. Adrian Percy:

So this concept has led to, or this understanding, I guess, has led to a lot of work around improving soil health, regenerative agriculture, and other terms like this. So can you talk a little bit also about how farmers are adopting these practices, such as reduced tillage or soil amendments or use of cover crops, to improve the plant-microbe interactions? What effect do those types of activities have?

Dr. Amy Grunden:

I will say that a truism that seems to be bearing out with research being conducted around the world is that the higher the microbial diversity in a soil system, generally the better off plant productivity can be because as you have more different microbes in a soil system, you have more of that chemical capability that I was talking about that microbes can provide for plants. And so if you have very low soil diversity, chances are you're missing a microbe that does a very key process that plants need, like solubilizing phosphorus for plants, or being able to fix nitrogen for plants to have to use biologically available nitrogen, or helping to provide to produce plant hormones that help with plant development, right? So some of the processes that Adrian spoke about, the no tillage or cover crops, those are processes that actually help with maintaining higher microbial diversity within a soil system.

Dr. Adrian Percy:

This whole area of research into the soil microbiome, but also, as you mentioned, above ... microbiome on the plant itself above ground has ... It's clear there's still a lot of learnings happening. What is our ... I'm curious how you would describe the level of understanding of the microbiome at this point in time. And what more needs to be done, if you like, to fully understand it?

Dr. Amy Grunden:

That's a really good question. And so one of the reasons I presume that Adrian is talking to me about this is that I do lead a multinational, multi-institutional project funded by the Novo Nordisk Foundation that's called the Collaborative Crop Resilience Program. And it is tasked with allowing us to truly functionally understand the microbiome associated with the very important staple crop, wheat. And the reason we wanted to go with wheat is it's grown all over the world under different growing conditions. And what we wanted to understand in this project is what is the core microbiome associated with wheat? And what are the core functionalities that have to be in that microbiome to afford as much benefit as possible? And so we are looking at the below-ground microbiome associated with wheat, as well as the microbiome that is on the leaves. And we are trying to understand if there is actually transit between the root microbiome and the leaf microbiome.

Speaker 1:

The North Carolina Plant Sciences Initiative impacts lives through innovative applications and discoveries. By leveraging cutting-edge research and technology, we address global challenges related to agriculture, sustainability, and human health.

Dr. Adrian Percy:

The Collaborative Crop Resilience Program has been going for a few years now. What is the status of it? Because I understand you've also got some additional funding recently. And so what is the status of the original program? And what are you doing with this new line of funding?

Dr. Amy Grunden:

Yeah. No, I appreciate that question. So we are, I would say, two-thirds of the way into the starting project. One of the things that we ... Yes, we want to understand what microbial communities are there that are associated with wheat, but we actually want to be able to do it in the context of developing predictive models for the microbial community. And so we are at the place where ... And I want you to appreciate the scale of this project. So we have, at any time in this project, between 120 and 150 researchers.

Dr. Adrian Percy:

And these are researchers coming from very different backgrounds as well, right?

Dr. Amy Grunden:

Yes. Yes. And I want you to appreciate too that with the Novo Nordisk Foundation, that means we are working with Danish universities, right? So we are working with the University of Copenhagen, the Danish Technical University, and Aarhus University, and then with North Carolina State University, as well as universities in England and the Netherlands and in Japan. So it's a very global effort. And we are actually looking at wheat production systems here in the US and in Denmark, and are actually doing sort of real-time comparisons between the two. And so this is helping us with getting a good understanding of core microbiomes associated with trait-matched commercial wheat varieties that are grown commercially in Denmark and those that are grown commercially in the United States.

Dr. Adrian Percy:

You're working on wheat now, but do you feel that the research will lend insights into what may be happening with other crops?

Dr. Amy Grunden:

Absolutely.

Dr. Adrian Percy:

Corn, rice, whatever they may be?

Dr. Amy Grunden:

Yeah. So part of the reason why we wanted to fully map out the microbiome associated with wheat is not only do we want to understand sort of that core microbiome structure and functionality associated with wheat, what is core to support any cereal crop? What seems to be helpful to support growth of this grain crop under conditions of low water? Okay. So water stress, under temperature extremes, under salinity conditions. And the reason we're interested in that is there does appear to be some relevance to what's happening with the wheat microbiome would say what might be happening with the rice microbiome under salty soil conditions, right? And there are definitely ... We're beginning to have even greater understanding that there are particular microbes that are very helpful for plants in dealing with high-saline soils, for instance. And that has a lot of applicability to rice as it does to wheat and increasingly to all of our important crops that we may grow coastally around the world.

Dr. Adrian Percy:

So if we could kind of zoom out, you talked about some of the research. What does this mean for growers ultimately? You mentioned the example where actually some degree of disturbance of the soil may be beneficial at certain points in time. Do you see this type of research ultimately then informing growers on soil health practices?

Dr. Amy Grunden:

Yeah, absolutely. So I think what's been really powerful with the research that we've been doing is, again, identifying what functionalities or what processes must be happening in the microbial community to support optimal plant growth and to allow for plant growth to continue under conditions of stress, of abiotic and biotic stresses too. So we've done some research where we're showing that particular microbiome members can actually help suppress some fungal diseases, which is really exciting.

Dr. Adrian Percy:

So maybe kind of pivoting to a slightly different topic around the use of sensors and models to ultimately help maybe growers understand the health of their soils and what they might need to do. Are these types of technologies integrated into your research? Or do you think they-

Dr. Amy Grunden:

Yeah. That's a really good-

Dr. Adrian Percy:

... will be?

Dr. Amy Grunden:

That's a really good question. And yes. And you'd also mentioned or asked, where are we at now? And I'd like to add to that, where we want to go. And where we want to go is I'd really like to include a lot more sensoring systems into our understanding of microbe ... Plant-associated microbiome dynamics. And what I would love to do is actually develop sensored sentinel plants that would allow us in real time to understand who's in the microbiome community, and relay it through sensored outputs we can see for the plant, right? So that we could have sensor outputs on how well the photosynthesis in the plant is functioning. Can we have some early readouts on susceptibility of the plant for different diseases? Can we have readouts on does the plant sense that it's getting sufficient nitrogen, phosphorous, et cetera? And those are all things that we could have used spectral imaging, for instance, to track.

And what we still need to be working on, and we have some ideas on how to do, is sort of in real time be able to have sensored outputs on do we see certain particular microbial community members there? And how is that tracking with how the plant is perceiving nutrient levels?

Dr. Adrian Percy:

So if there is kind of one message that you could give to people listening to this about the importance of soil health and the impact of climate and the need for climate resiliency, what would it be?

Dr. Amy Grunden:

I think microbes absolutely have a hand in how we are going to successfully deal with increasingly stressed crop production systems. And again, I already mentioned the truism that the more microbial diversity you have in a soil, the greater your chance of that plant being able to withstand unideal growth conditions. And so I think that we need microbiologists, crop physiologists, need to work together to help decide on the best management practices along with the best understanding of the microbiome to help growers understand if I use this practice under these times and have a sense of ... And have a good understanding of the soil health of their system, that that would be really powerful in terms of de-risking agriculture.

Dr. Adrian Percy:

Great. So Amy, thank you so much.

Dr. Amy Grunden:

Thank you.

Dr. Adrian Percy:

Thanks for helping us to understand the science behind the soil biology and crop resilience. Really fascinating conversations. And we're really excited to see where your research takes you in the next round.

Speaker 1:

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