Fungi matter | Dr. Demetra Kandalepas

I'm a wetland ecologist that studies fungi. When I tell people I study wetlands, they get it. They know why that's important. When I tell them I study fungi, I get a lot of blank stares. I get some awkward silences. Some people actually are compelled to tell me about the black mold they found in their bathroom … I remember someone trying to explain to me that their uncle had a fungus on their toe and … ” Okay, good times. Yeah, that's good.”  So, I do get some people that tell me that they don't understand why I would study such a thing.

In the grand scheme of things with all the problems going on in the world, fungi really don't matter. Well, that hurts a little bit. But I'm here to tell you that fungi do matter. And you probably all have a reason for either hating or loving fungi or both. I'm here to tell you that you probably can't even imagine the scope of what fungi do for you every day and what they could potentially do for you. So, when you think of fungi, you probably think about some of your favorite fermented foods or beverages.

Yeah, those are all really great. Some of you might be avid mushroom hunters like I am. Some of you might opt to grow your fungi in a dark closet in the house. That's okay too. I don't question that. But for all the things you think about when you think about fungi, I'll bet you don't think about what they really do. You don't really have a true appreciation yet for what they do for us. You probably don't think about the fact that without fungi, we'd probably be buried under mountains of plant debris, and maybe animal carcasses, and quite literally, a lot of shit. These things are incredible composters. They are the garbage disposals of Nature. The fungus that you see right here, you probably recognize it as an oyster mushroom.

It's a great treat when I find it in nature; I love it. But it has a dual lifestyle. It grows on dead wood, and the reason it does that is that it needs the cellulose, which is a component of wood. It produces these potent enzymes that can only break down wood. Without them, you couldn't do that. This fungus can only get sugar from cellulose. It still needs nutrients, so where is it going to get the nitrogen from? Well, it has developed a really intricate – I should say “ingenious” or maybe “sinister”- way of getting its nutrients.

It forms these little microscopic rings, these “lassos” if you will. And these microscopic rings are the perfect size for this microscopic parasite. It's a little brown worm called a “nematode.” This little nematode, unsuspecting, comes along. It crawls through this little lasso, and as soon as the fungus detects it, it grabs onto it. The worm tries to escape, but it can't. And very promptly, the fungus devours it. So, fungi do a lot of things for us. But because of all these potent enzymes, they've also developed a reputation for being nuisances. So, we consider them our competitors, if you will.

And some are even more of a nuisance than others. There's Uncle Joe's toe … But they're not all nuisances. There are some that are quite literally a miracle. I mean, they have saved lives. The metabolites that were found quite accidentally in this fungus right here called “cyclosporin” have enabled us to perform organ transplants. They suppress our T-cells, and so we don't reject the organ. So that's just one example of how amazing these things could be. But we've only scratched the surface of what they can do, and how we can use them, and how Nature needs them. So, we have to continue to study these things. They have a tremendous amount of diversity in color, in shapes and sizes, they're beautiful! When you find them in Nature, you're always mesmerized, am I right? They're just gorgeous things. And they all have different functions. They all grow in different substrates. But we've only, like I said, scratched the surface. We've only described 70,000 of these fungi. And I say “only” because it's estimated that about five to eight million more exist.

So where is all this hidden diversity? Where are we going to find it? Certainly, you don't look out the window and see everything covered in really pretty fungi. That's not where we're going to find it. But in the last couple of decades, there's been a great boom in research in mycology, and where, we think, most of the diversity is going to come from is from plants. Fungi are so abundant in some plants, that if you take away all the plant tissue, you'll be left with a skeleton or some sort of a ghost of the plant, and that will all be fungal tissue.

So these fungi are found in all organs, all parts of the plant. They're found in the roots, in the stems, and in leaves. They've developed a name for them. They call them “endophytes,” “endo” meaning in, and “phyte,” plant. They cause no symptoms of the disease to their plant, so they're known to be beneficial to the plant. They live there, invisible, happy until something happens to the host. Now, these fungi are so vast, there're so many of them that I've chosen to study only the foliar endophytes. That's enough because these have shown to be hyperdiverse. These things are so abundant that one could spend a lifetime exploring these fungi just in the leaves, and never really get anywhere, and still have several lifetimes to go. How do they get there? Well, typically through air currents. They fall from other trees, other plants. They come in, they settle on the surface of the leaf, and if they can penetrate the cuticle and tolerate the plant's chemistry, they get to stay. And they stay there happily. So if you could all just take your fingers and do this, and look through that little hole, that's about the area that one fungus can occupy in a leaf.

So you can imagine how many you can cram inside a leaf. And they all coexist happily. They don't fight; they don't compete. But when a competitor, a true competitor, comes in and tries to attack its host, well then there's trouble. They put in place all these metabolites, all these enzymes, and they really do go to work to try to protect their host. But they also have a lot more benefits to their host. We have found that fungi can not only protect their plant hosts from pathogens and herbivores, but we've also been able to show that they can induce drought resistance to their host, salinity resistance, flood resistance; they can tolerate low nutrient conditions. So there are a lot of things that these fungi can do for their host just by sitting and living invisibly inside their host.

And this is important for my research, because all these conditions exist in south Louisiana, in coastal Louisiana. We're losing land at a rate of about a football field every hour, here. That is the fastest rate in the entire country and most of the rest of the world. So you can imagine that if fungi can help their plant hosts overcome things like flooding and salinity, then that might be a key to saving our wetlands. If we had cypress trees that could tolerate salinity, we could plant them below New Orleans and have them as a barrier to disasters like Katrina. So that's where my research is sort of heading. In about 90 years, we're expected to have about two meters of flooding, which would make Baton Rouge – that star that you see up there- in about 90 years, Baton Rouge may very well be a coastal city.

So this is pretty serious. We're losing it at an accelerated rate. Now, the reason some of these things are happening is that we've carved up the land. About a century ago, we removed the vast majority of the thousand-year-old cypress trees that were out there, and so we created logging ditches that are permanent. We also have allowed the oil and gas industry to completely carve up the coast.

And so what that's doing is allowing the salt water from the gulf to come in and intrude into the freshwater communities affecting those freshwater plants, but it's also making those plant communities susceptible to hurricanes. So, the first step in this kind of research is to find out whether these plants even associate with fungi. Nobody has ever studied wetland plants in Louisiana for their fungal component. That's the first thing I did. In comes Hurricane Katrina. We simulated a hurricane in a greenhouse – an outdoor greenhouse, mind you. And the way we did that is by using a large area where we planted a whole bunch of trees in a whole bunch of barrels, and the red circles that you see up here are circles that were affected by the hurricane.

So all these represent barrels that had plants in them. And then we imposed a hurricane onto the red barrels. The blue barrels were untouched by the hurricane. Those were our controls. We manipulated salinity, nutrients, and sediment … That was it. Then, Hurricane Demetra came in on August 4th at a.m. in 2007. And we modeled Katrina for this hurricane. We actually had sustained winds of 125 miles an hour, with maximum wind speeds of 152. It was a pretty cool experiment, and all we had to do was to find a Cajun with an airboat. That was not hard. All we had to do was to give him a couple of beers, he was good. The roof blew off very promptly, and this is the scene six hours later. The plants were all bent out of shape. The leaves didn't really fly off the trees or anything, but the plants were pretty mangled and shredded. This is pre-hurricane, immediately before the hurricane. Here's another picture showing immediately after the hurricane, and another picture showing one month after the hurricane.

You can see a lot of regrowth here. You also see a lot of dead leaves, but those were the leaves that were affected by the salt, the high salinities that we imposed onto these barrels. But it's really positive that we see all this regrowth. And that's really positive for me because I got to collect these leaf tissues. So what I did was I collected leaf tissues and cut out little squares and put them on a nutrient medium. After I did that, I waited for the fungi to grow out of the cut edges of the leaf tissue. And that's when I got my cultures. I was able to identify a lot of these fungi. In fact, that's a lie because about 80% of the fungi that I got from these cultures were unidentifiable. They've never been described. There was no name put on them. I couldn't attach a DNA sequence to something that's already known. So there is, indeed, a lot of undiscovered diversity in these wetland plants.

But what I found was that one month after the hurricane, there really was a tremendous amount of diversity in fungi. The fungi that you see right here came from a leaf area of about the size of a nickel. And that is in the affected plants. In the controls, in the unaffected plants, we saw double the diversity. So you can see that in a month's time, we already had fungi responding. So, how can we use this information? Well, I already told you that plants benefit from these fungi because they confer benefits of drought resistance, flood resistance, salinity, low nutrients, extreme temperatures, and even protect them from the herbivores.

So if we could find fungi from what we're sampling right now that will associate with these plants, that will actually confer these benefits to the plants, we could have a really great way of planting cypress in salty areas so that we can actually have a barrier for our future Katrinas. And the other way that we can use this information is as a signature. If we look at an ecosystem right now, and we see that it's dying, it's too late, right? We have to start suddenly pumping millions of dollars and lots of manpower into fixing this. But really, there's very little hope that this will come back at this point.

If we look at the trees, well, individual trees won't really tell you much until it's too late either. It might take two years for a cypress tree to show you that it has been suffering from drought and salinity for the last two years. It'll be dead by the time you find it. Herbaceous plants, well, they respond a little bit quicker, but they still could take up to a growing season to respond. Again, by that time, too many plants might be affected in the ecosystem. But fungi respond immediately. We saw that these things already were responding within a month of this high stress that was imposed onto their plants. If we could monitor fungi on a regular basis and find out which fungi live under which conditions, and recognize differences in these fungal communities immediately, then we could actually prevent problems before they become too serious.