In this episode, Cole and his guests discuss Penn State’s launch of the world’s first Center for Parasitic and Carnivorous Plants. These fascinatingly strange organisms have much to teach us about the outrageous diversity of life - especially now that we have the capacity to study them at every scale, from the molecular to the ecological.
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In this episode, Cole and his guests discuss Penn State’s launch of the world’s first Center for Parasitic and Carnivorous Plants. These fascinatingly strange organisms have much to teach us about the outrageous diversity of life - especially now that we have the capacity to study them at every scale, from the molecular to the ecological.
Relevant Links:
Guests:
Intro (Nina Jablonski): Evolution involves more than the survival of the fittest. It's also about the survival of the most cooperative and mutually beneficial relationships are critical to the survival of every species. Welcome to The Symbiotic Podcast, where we will explore the collaborative side of life and work to consciously evolve science itself.
Cole Hons: Greetings, fellow Homo sapiens, and welcome to The Symbiotic Podcast. I'm Cole Hons, and today we're going to be talking about a really exciting new center that we're starting up here at Penn State. It's the Center for Parasitic and Carnivorous Plants. And joining me are three of the faculty members who are helping to get that going. First of all, we've got Claude dePamphilis, professor of biology, his research centers on genomics, bioinformatics and molecular evolution. He studies the origin and diversification of flowers and developmental pathways, the comparative genomics of plants, organelles and plant gene families and the genomics, evolution and functional biology of parasitic plants. We also have Tanya Renner, assistant professor of entomology. Her research focuses on the evolution of chemical and structural defense. She studies molecular evolution, evolutionary genomics and transcriptomics. And she's particularly interested in the origins and evolution of carnivorous plants.
Also with us today is Tomas Carlo-Joglar, associate professor of biology at Penn State. He studies seed dispersal ecology, foraging behavior and plant ecology. In particular, he looks at interactions between plants and animals that eat fruit and disperse seeds and strives to understand how the foraging and movement behavior of fruit eating birds has an impact on the patterning, demography and migration of plant populations and diversity. Welcome, everybody. Thanks for being on the podcast today. So this is pretty exciting that you're starting up this new center. I'd like to hear all about it but first, I want to find out from each of you, just go around the table and find out what inspired you to go into this field? What made you take this on in your life? Can I start with you, Claude?
Claude dePamphilis: Sure. Well, as a biologist, I did see many parasitic and carnivorous plants as a child growing up and saw them and wondered about them. But it really wasn't until I started to learn about molecular biology and molecular evolutionary biology that I began to think that there were things I could do with them to really study questions I was interested in for a very long time. So it was the creation of a new field, molecular revolution and thinking that molecular evolution could be addressed with carnivorous and parasitic plants, and those plants could inform our understanding of the process of evolution.
Cole: Cool.
Claude: How about you, Tanya?
Tanya Renner: Yes. So when I was a young kid growing up in California, I went to a lot of botanical gardens. And in those botanical gardens, there were a lot of carnivorous plants. The ones that were hanging over other plants, the big pitcher plants that were super exciting and charismatic. And I was really interested in those plants from an early age and I wanted to know how they worked and why they were different from other plants, because they looked pretty weird, so they must be different. And so when I started my studies as an undergraduate, I got really interested in molecular evolution too and how do we get new proteins? And what are those functions of those proteins? I got super excited by staring at nucleotides and amino acids. I was a pretty big genetic nerd. So when I had a chance in graduate school to get back to these plants and figuring out how they're different, I really wanted to do that with molecular genetics. And that's how I came to study carnivorous plants for my profession.
Cole: Cool. Thank you.
Tomas Carlo-Joglar: Yeah, so my story started with birds. Birds brought me into biology really. I started as a young bird watcher, and photographer really. And those interests took me into grad school eventually and my advisor gave me [inaudible 00:04:18] bird foraging. And in the tropics, a lot of birds eat fruit and that's how the forest moves. So I started with animals and the animals show me the plants. And one of the plants they show me, very notoriously were the mistletoes. So my master's project had to do with studying [inaudible 00:04:41] patterns. Mistletoes were a big part of it and I couldn't really identify them by species only by genera in Puerto Rico. And then I find out that nobody knew them. Back then nobody knew the species really. So that's my connection with this group is with studied mistletoe fruits. It turns out also that there's a lot of fascinating ecological questions that lower ecologists to start studying mistletoes because mistletoes are crops that grow on other plants in the above ground parts. They're very special in that sense that you can identify their habitat pretty clearly, versus plants that grow on the soil that is kind of more pain and diffuse. So mistletoes are really cool in that sense. They have their habitat on other plants, and they lend themselves to experimentation, for example and their patterns in terms of how specific they are, their gradients.
Some, you have more specialized plants, and more generalized plants, parasites. And so those questions were always there and as I became an independent researcher, I started looking the question from the plant's perspective more. And one of the fundamental questions in ecology, what are the drivers of the distribution of abundance of species? In the case of plants that are moved by animals, you have to study the animals to understand those patterns. And it's hard to predict versus the influence of temperature, humidity, which are more clear cut, and the major driver of distributions beyond that is actually biotic interactions like this mutualism between birds, and protein plants. And that's where I fit in this group.
Cole: Oh, we love that. Because it's typical of the work that you do. We have to study animals and plants, we have to study all the interactions of all these different life forms to get that bigger picture and really see what's going on. That's great. So I'm going to swing back to Claude and say, seems like you all had this interest before. Now, what made y'all come together and say let's make a center at Penn State? How did that come about?
Claude: Right. So, I guess I've been here the longest of our members. And over the years, I've really seen the interest in parasitic and in carnivorous plants just grow. So I lose no opportunity to talk to people about these really interesting organisms and my underlying theory of this is that these plants are rule breakers. They break so many of the rules of normal plant biology, for example, some of them have lost their ability to photosynthesize. The carnivores of course, by eating animals break the fundamental rule of plants being on their own autotrophic switching the food chain in an opposite direction. There's much we can learn from this. So I always can talk with people across disciplines and fortunately, people started to arrive at Penn State who were interested in these organisms. So Tomas came and he was interested in mistletoes, and birds. And we have a colleague Mike Axtell, who works on small RNA and how plants make small RNAs as regulators of gene expression. And what Mike was able to learn was that parasites and hosts communicate by small RNA communication and the parasites can silence genes that are defending the host plant.
So these are really fundamental things that can be learned and I would say one at a time, members of our group have either arrived on campus or changed some of their research to try to ask a question from their own specialized perspective, what can I learn from these plants? The answers turned out to be quite a lot. Now, I would say that Tanya is our most recent new faculty member who has come to bring a real research specialty in carnivorous plants, and that was something that this collection of scientists didn't have before. Another new hire in the plant science department studies, microbiomes of plants and now he works on microbiomes of parasitic plants. I would say it's just become like a snowballing effect. Once people start to think about these as interesting organisms, there's so many things we can learn about them.
Cole: Right on. Thank you. So kind of organically happened as you reached the critical mass of expertise and the right people all being here together and all having that shared passion, it sounds like.
Claude: It did.
Cole: And what did you do with that? How did you get to form the center?
Claude: Well, we actually started two years ago, and we began holding joint lab meetings. And we had five faculty members at that point, holding joint lab meetings talking about then, just parasitic plants, realizing we had a lot of overlapping interests. And then Tanya came and Francisco came, we got seven and we realized, we're actually acting as a center in many ways. We're interacting, we're collaborating, we're starting to write papers together and write grant proposals together. We really were functioning like a center so we decided to apply to be one [crosstalk 00:10:23].
Cole: Might as well [crosstalk 00:10:23].
Claude: Yes.
Cole: Make sense. Does anybody have anything to add to that? A different perspective on that?
Tanya: I think the really unique thing is that everyone has their main objective, right? And they're an expert in that one, and maybe a few. And so it's really complimentary between all of the P.Is that are associated with the center and I think that's what makes it really unique.
Cole: So Penn State's really the first university anywhere to take on this specialty as a center that we're aware of, correct?
Claude: That is right. We don't know of any others, and already I think we can say we're the leading Institute for the Study of Parasitic and Carnivorous Plants. It's okay to be just one, we're already big.
Cole: Right on. Well then, let's start to talk about what we do now. Why are these two kinds of plants lumped together? Is the question that comes to mind for me. Maybe you could talk about that a little bit. What is it? Why is it not just parasitic or just carnivorous?
Claude: Well, the common theme is that they are rule breakers. And the common theme is that they each take something that you think of as typical of the way plants should be, and they change it. And for example, parasitic plants are stealing nutrients from their host plants through modified roots, carnivorous plants are getting important mineral nutrients from animals by trapping and eating them. These have so many effects on the way these organisms evolve, how did these adaptations evolve? What changes occur in these kinds of organisms? Surprisingly, there's some really big commonalities in their molecular evolutionary changes and the kinds of adaptations that you see. Even down to the level of individual genes that are evolving in common between parasitic and carnivorous plants completely independently, but achieving the same change through independent changes to achieve a similar role.
Cole: That's fascinating. And are they distributed all across the globe? Is there a hotbed for both or either of these?
Tanya: So for the carnivorous plants, there's a few that we would consider to be cosmopolitan, so we find them in a lot of different places. And then there's some that are in very particular places, but when considering the habitats that they're in, there are often these areas that have low nitrogen or phosphorus. So bogs, sandy areas, tropical areas where the soil isn't good. So that's one commonality around all of those, is that they're not able to get enough of their central nutrients from soil sources. So they have to find other sources for that. And that can be insects, that can be animals, it can be other plant material, it can be scat from other animals. So there's many different sources they can get those essential nutrients from.
Cole: Interesting. And do they both show up on the evolutionary timeline roughly at the same time? Do we know anything about that?
Claude: Well ... let's see. When we look at parasitic plants, basically they are mostly all flowering plants. There's one lineage of parasite, that is gymnosperm. So this puts them in the relatively recent timeframe. We've got 12 different lineages of flowering plants that have evolved parasitism and it accounts for about 4500 species or one and a half percent of all flowering plants. Carnivorous plants ...
Tanya: Yeah, so kind of a similar story, they're all flowering plants. So it's relatively recent if we're talking about geological time. The interesting thing is that there's also these independent origins of carnivore throughout flowering plants, we think upwards of 10 separate times within five flowering plant orders. But yeah, I would say the same, it's pretty recent. There were some initial ideas that maybe carnivorous plants were ancient because they ate animals but we've really debunked that with genetic data.
Cole: Is that right? So aren't just like eating dinosaurs, giant carnivorous plant, Venus flytrap.
Tanya: Yeah, there's some interesting things out there, stories ...
Cole: Do we know who showed up first? Which came first carnivorous or parasitic? Do we know that?
Tanya: I don't think we're quite there yet. The thing is that we don't really have that very good of fossils for carnivorous plants. There's pollen out there, seed but often these plants are in areas where we don't get really good fossils for them. So some of this is based on genetic data and trying to figure out how old they are. But we don't know that for a lot of groups.
Claude: The interesting thing is that a couple of lineages have managed to evolve both carnivorous and parasitic plants. And one commonality in there seems to be that there's a process in plants known as whole genome duplication, or polyploidy. And when a genome of a plant duplicates, it creates a doubled set of genes, the entire genome doubles, and then something happens usually most of those genes will with time decay away. But some of them get used in new processes. And in the case of parasitic and carnivorous plants, sometimes they've evolved from the same whole genome duplications and utilize some of these plants and some of these genes for two very different processes.
Tomas: In the case of mistletoes, they have kind of a split personality, most of them. I mean, compared to the real monsters out there like the carnivorous plants and the whole of parasites. So many mistletoes are ... Hemiparasitic. What they call hemiparasitic, saying that they photosynthesize, they haven't lost their ability to green, they have leaves, and they're just tapping mostly the xylem of the host, which is the piping ... water nutrients, they're kind of parasitizing the root system. And so they're not totally there, although some of the things we're interested in looking at is, is looking at those gradients. A population within the same species that are more parasitic, heterotrophic, then autotrophic and exploring the conditions under those things that start to evolve is interesting. And the thing with mistletoes as well I can mention is that they also have this mutualistic side. They are important resources for animals, particularly birds, but also some mammals. And as well as hummingbirds even the flowers and insects can be very important for resources. When we are in the group, I hear a lot of conversation that can have negative connotation of the impacts of parasite on crops and things. And I'm always thinking also the positive side that parasitism can have in ecosystems or the split personality. On one side you're a parasite and the other side you're important mutualists as well.
Claude: Context is everything, right?
Tomas: So mistletoes have that that peculiarity, compared to other parasitic plants. [crosstalk 00:17:58].
Claude: That is very interesting. We do know that some of the parasitic plants are extremely damaging. A plant like witch weed or Striga is one of if not the most important cause of damage from a biological source in Sub Saharan Africa meaning hundreds of millions of people are really suffering from food insecurity due to the direct effects of Striga on corn and sorghum and other grain crops. So they do do a lot of damage. If we find the right cases, they're terribly devastating, damaging parasites. But just like you say, some of these parasites when you look at them in their role in nature, some of them have very interesting complex roles. Some of them have no known detectable damage really to the host. Others might focus on the competitive dominant in the plant community, and in doing so, open up more opportunities for a wider diversity of plants to survive and grow, make the habitat more complex.
Cole: Interesting.
Tomas: Yeah. They can increase their turnover species, and that allows for more species to be able to coexist in smaller areas or in the long run.
Cole: I heard you say there are over 4000 species of parasitic plants. And how many species are there of carnivorous plants?
Tanya: Over 1000 species.
Cole: Over 1000. Everybody just thinks of Venus flytrap.
Tanya: Yeah, that's the one species.
Cole: Yeah, that's mind blowing. What else do people have no idea about when it comes to these plants?
Tanya: Well, some carnivorous plants have what we would call the fastest plant movement out there. So there are some aquatic carnivorous plants, Utricularia or bladderworts common name, and they can move in like a millisecond to help capture their prey using a suction type trap.
Claude: Well, in the parasite world, we see things like some parasitic plants can kill their host even before the parasite is visible. That is this plant that we've talked about called Striga or witch weed. It does a lot of damage below ground, and it does damage that's way, way beyond the amount of nutrients that it has stolen, physiologically altering the host and killing the corn plant if that's the host before you even see the Striga plant. So sadly, when the Striga comes up and flowers and looks beautiful, people didn't necessarily connect the damage that was done to their crops to the activity of the parasitic plant. So you would pick these and make lovely flower bundles of the Striga flowers.
Cole: Wow.
Claude: And that would help spread the seeds around and cause a greater problem.
Cole: It was a sneaky, sneaky plant.
Claude: Surely is.
Cole: Wow. We heard a little bit about the mistletoes also being unique in the fact that maybe there's some negative things there but also some positive things in the ecological context, right?
Tomas: Yes. So mistletoes are considered keystone resources in many communities in tropical and arid tropical systems. They can be very very important for animals. In Patagonia, there's this mistletoe that flowers and fruits during the winter which is amazing and it sustains a non-migratory species of hummingbird. Imagine a hummingbird in a place that snows and you have mistletoe covering snow and then you have these big flowers just coming out from the snow cover and then this huge hummingbird using it. And at the same time that same system is a system we have worked in the past in [inaudible 00:21:52], Argentina. This mistletoe is dispersed exclusively by this nocturnal marsupial and it walks through the branches and as it does so it deposit the seeds, the sticky seeds ... So mistletoes have a lot of cool adaptations. The seeds have to remain on the aerial parts of other plants otherwise they cannot get any [inaudible 00:22:17] seeds germinate immediately.
They will germinate in this table if you put them here, in the air, anywhere, they germinate immediately. But they need to find a suitable branch to be able to leave after that period. So these animals are really good at planting them as they walk through these little branches. And we have done some studies about that. Mistletoes also have medicinal uses. They're studying some cancer treatments in the European mistletoe have been developed. They have a lot of weird proteins maybe related to the fact that they are ... can grow on other plants and this is something that other parasitic plants or [inaudible 00:23:00] plants have. They have weird proteins. So they have both medicinal uses, they're using medicine. And they also have a lot of folkloric meanings. Because [crosstalk 00:23:13].
Cole: Right. Kiss under the mistletoe. What's up with that?
Tomas: Well, that those are traditions from Northern Europe like Gallic ... those pre-Germanic cultures. They prized the mistletoe, both because they used it as a medicine. So mistletoes are poisonous, so they have been used to make poisons. And it's just extraordinary to see this plant growing from another stem and it's totally different. It's kind of mysterious.
Claude: That's right. In honor of how strange these plants are, they get some of the best names of any plants. So there's one that we work on, that this group works on, it's called [Adata Kaskuda 00:24:01] but it's got nicknames like love weed and tangle vine and tangle weed. And it's a plant that just looks like a big bowl of spaghetti draped out over onto its host. And this plant is, of course a parasitic plant. Other ones like the strangest plant in the world is a plant called Hydnora, and it grows in the deserts of South Africa. And this plant basically has given up all leaves, all roots ... there's this real big underground, strange root but it has no photosynthesis. And when it comes up out of the ground, it's coming out from its host, it grows up with such force, that it will break asphalt or concrete and destroy your house if it happens to be coming up under your house.
Cole: Wow. That's a powerful plant.
Claude: Yeah. We really haven't even gotten to some of the weirdest ones yet. So there's one called Rafflesia. And Rafflesia has the largest flower in the world of any plant. And it grows almost its entire lifecycle inside its host. It grows like a little fungal strand growing inside its host, gathering its energy and then it comes out to flower. And it smells. It smells like carrion and it attracts carrion flies.
Cole: Oh.
Claude: Yes.
Tomas: [crosstalk 00:25:32], right?
Claude: [crosstalk 00:25:35] and orange.
Cole: Where are those found?
Claude: Southeast Asia.
Cole: Southeast Asia?
Claude: Yeah.
Cole: What's the name of that?
Claude: Rafflesia.
Cole: Rafflesia. Not having that for dinner. What are some of the carnivorous plant?
Tanya: Yeah, so there's some very weird carnivorous plant names out there. So I mentioned the bladderwort, that fast moving trap but in that same order, we also have butterworts, Pinguicula. We have the corkscrew plants, Genlisea. And then outside of that in other words we have the Venus flytrap that you were bringing up earlier, sundews, the pitcher plants like Nepenthes. So there's a bunch of weird names out there for these cool plants. I was just thinking earlier about the weird proteins that you were bringing up and medicinal uses too. So sundews for example, make anti-microbials and have been used for medicinal purposes to prevent infection and whatnot and people will take tinctures of them. And then the slime that the butterworts make to digest and sex can be added to milk to culture it to get this cafe like milk and that's been used in other multiple cultures. So yeah, there's some kind of weird things out there too we can use them for.
Cole: Interesting. Who knew that this was also diverse like that? I had no idea. I think people have no idea about that. So you'll get to play and discover even more about these plants. And for our knowledge globally, really, right here at Penn State, that's super cool. So we're going to take a little break, and then when we come back, we'll start to talk about how the different disciplines are going to be able to come together in this new center to unfold the stories about these amazing plants. Okay, so I'm Cole Hons. This is the Symbiotic Podcast, we'll be back in just a minute. Thanks.
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Cole: Welcome back to the Symbiotic Podcast. I'm Cole Hons and we're going to get into part two of our conversation about Penn State's new Center for Parasitic and Carnivorous Plants. So in part two, I'll be talking to my guests here, you folks about the interdisciplinary integrative transdisciplinary nature of what you're doing. I'd like to hear a little bit about what you've done so far and where things are and where you might want to take that.
Claude: Well, for the last few years, various of us have collaborated together in different combinations. We've collaborated to build unified stories or studies that go from evolution to genomics to systematics and ecology and really tried to bridge a lot of disciplines within the broad view of biology that often don't really come together.
Cole: And so you did some papers together, et cetera, based around that?
Tomas: [inaudible 00:29:17] a wonderful student, Marcos [inaudible 00:29:20], now a postdoc in the Smithsonian Institution. And yeah, Marcos with me, he works on ecological side of this mistletoe in the Caribbean. So I'm an ecologist and I'm interested evolution, of course. But we also need to nail down how evolution happens, and that involves molecular work. And that's where knowing about the genes, what genes have been expressed or not, what they do and how they perform in different environments and what those environments means for different characteristics essentially. The problem with evolution is that traits have value depending on where they are and these are ever shifting conditions. So that's what takes the determinism out of the equation. So we need to be able to be in context to understand value and what makes sense and what doesn't make sense. So it requires really go through cross disciplines, to go from the context ... understanding context and what makes sense or what doesn't, to how things work at a molecular level.
Cole: So what kind of experts need to be in the room or involved in order to paint the picture we're looking to see?
Claude: Well, really, it's going to take a range of scientists that have a focus all the way from ecology, through cell biology, development, molecular biology, and molecular interactions. Tanya's work goes all the way to protein modeling and trying to understand the functional specific proteins as they're involved in the carnivorous process. And that is commonly what we're trying to do with the parasites as well. So we're taking these questions all the way from the ecological stage all the way through to the molecular biology of these interesting organisms.
Cole: Very cool. Do you care to comment on that at all, Tanya?
Tanya: Yeah. I think that at this stage, we've got a lot of different disciplines in a way in biology from the ecologists down to the molecular side of things. And I think at some point, we're really looking to branch out and maybe bring some folks from engineering in here, material sciences to understand once you have this plant structure, how does it work with the outside life? And so that would be definitely then the next step.
Cole: Cool. That sounds exciting. When you've worked with folks who don't share your specific discipline, what kind of challenges arise for you in order to make those partnerships work? Could anybody share some personal stories on that front?
Tomas: I just understand very little what they're talking about most of the time.
Tanya: Yeah. So I have a current collaboration where I work with a chemist, it's at the Stevens Institute of Technology [inaudible 00:32:19] and chemical ecologist that's at UC Berkeley. And so that's a pretty ... to bring chemistry and biology together in the same room. You wonder if someone's going to start duking it out. But I think it really comes down to the major goal, and how to bring people from those very different disciplines find out that common goal and approach it in different ways. And I think that's what we're trying to do here is tackle this major question by coming at it from different areas.
Claude: I agree. Well, I think these weekly meetings really do help that we're having and this has been possible ... Now that we're center, we're able to identify problems that we would love to address in common, and think about ways to address them. And being a center funded by the Huck is allowing us to bring in visiting speakers, people who can run workshops and help us really concentrate on an integrative method that might be able to be used to address one aspect of this question of how these evolved or how they function.
Cole: Can anyone give an example in your work in the past where through a cross disciplinary or an integrative effort, some new knowledge emerged that wouldn't have happened if you didn't have those diverse people in the room, that relates to these plants that we're talking about?
Tomas: You're looking at me?
Cole: I don't know. Everybody else is looking at you. That's because you work with animals and plants.
Tomas: I mean, we're just starting to look at that, but we have seen ... just looking at patterns of distribution and characteristics of mistletoes and things that are relevant for their life histories ... So, things that I can see are fruit size, how much fruits they produce, their fecundity and things like that. So, we see variation and now with ... for example what Marcus did, he find some genes that may explain some of the differences, like some genes that are associated with salinity resistance. And some of these genes seems to be more common in some species that occur in drier environments and closer to the coast.
Cole: So without having him [crosstalk 00:34:50].
Tomas: Yeah. So this is work they did with Claude and things that I'm always oblivious to, but now I can ... Oh, okay. There's some functionality here at the molecular level that could be starting to explain pattern. That's not the kind of thing that we want to really look for really, is to how these things come together.
Cole: So what's happening at that molecular level having an effect on the large [crosstalk 00:35:20]?
Tomas: Yeah. So you need to go from the molecules to the phenotype and the interactions that give meaning to the phenotype. That's the part that where I feel like I'm into. For example, how birds disseminate seeds in the environment is incredibly heterogeneous to a fine scale. That's one of the things we learned in Marcos's dissertation, one of his chapters. It really surprised me because I have been working with bird and see dispersal for a long time, but I didn't expect this seedling to be so finally structured in space. So that when you take a common tree almost never received seeds of mistletoe.
And he said, "Very common tree and then when we plant them doing an experiment, a common garden experiment, then we see that they can grow well." So that's fantastic. So one of the things we did was try to partition that, how much of the pattern that you see in the distribution of these plants relates to host's incompatibilities, and to how the animals are disseminating seeds in the environment. Okay. And for me, that was fascinating. So that's a sort of variation, and then you have other factors that are molecular. There are incompatibilities, but you need to understand how these two things come together to create pattern in nature, really. And most studies just stay or at their ecological realm or the molecular, they're really not many seeds across the entire spectrum. That's the challenge, and that's why we need to go. I mean, that's where NSF is really pushing [crosstalk 00:37:08].
Cole: Connecting the dots.
Tomas: But it's easy to say, we need to ... yeah, and I think we have a great team, and we're going to be able to identify study systems to meet some of those questions.
Cole: Very cool. And then do the different disciplines have to come together to explain why these plants decided they needed to either be a parasite of another organism or eat flesh? Like, I guess all these different ... whether you're at the molecular level or the ecological level, the answers are different, correct?
Tanya: Well, I think they help to inform each other. So to be able to go out into the field and see a plant that's eating an insect or a parasitic plant on another plant, you have to make some observations about those adaptations and how those are influencing multi-species interactions. And then that underlying thread of those interactions is down there at that nucleic acid level. So you really have to come full circle to really understand those things really very well at a very fine detail from the large side of things as ecological interactions all the way down to the nucleotide side of things.
Cole: And I'm sure there's a computational piece of this as well, with all the data that seems to be a very common theme among everybody in the life sciences right now that that's getting more important. Anybody want to chime in on that?
Claude: Sure. Well, this is exactly right. I think one of the unifying bodies of knowledge that's growing very, very rapidly is our knowledge of genes and genomes of these organisms. And this is one way we can make a connection between all of these natures of studies, how these organisms have modified cell walls in very unusual processes for manipulating cell walls and their hosts or the carnivores, they can move their cell walls very, very quickly. Some of the same things that we can learn come by examining these genomes. Did you know for example that just by looking at the genome data that exist, it's possible to see that the carnivorous plants have the very smallest genomes of any plant known. Whereas the parasitic plants have many of the largest genomes of any plant known. Despite their commonalities, what they're doing is exploring two very, very different regions of what you might think would be pretty well a set story for plants is how many genes do you have and how big you are. No. They vary by hundreds of fold and by having that rule broken, we are probably going to be able to understand what makes a plant genome really work, and why it's structured the way it is.
Cole: So what other examples can you guys think of that crossed boundaries in terms of disciplines and brought forth some important new knowledge in this area of these parasitic and carnivorous plants?
Claude: Well, one thing I can think of is basically discovery that occurred over really a period of decades a bit at a time. And what we knew in the world of parasitic plants was there was a chemical signal being exuded by the roots of the host plant that was being picked up by parasites like Striga to stimulate germination of the Striga seed. Now, you'd asked why in the world would a plant exude a chemical that the parasitic plant is using to target it? Didn't make sense. Well, it also turned out that once we understood what this chemical, strigolactone was doing in plants, it turned out it's a hormone, the newest discovered plant hormone that regulates plant growth, has important role in plant branching, and also is exuded by plants to call in mycorrhizal fungi when they're under stress. So we connect mycorrhizal fungi plant growth to things the plant must have with the strigolactone and then the parasites. Now what we realize is, parasites are basically observing and sniffing around for chemical signals to say, now I've got a host to attack. So this really brought together all sorts of disparate fields, including chemical biology, plant physiology, mycorrhizal interactions and multi-way trophic interactions.
Cole: Cool. So does that become a model of where we might be able to go with our center looking at examples like that?
Claude: That's exactly the kind of thing we'd hope to do. Look very synthetically at least fundamental problems and fundamental questions that the parasitic plant and carnivorous plants together can address.
Cole: Cool. While we're still on this topic of the different disciplines, maybe you could talk about who else is in this center as you're just getting started. There's the three of you in the room and I think there are four other faculty members signed on and you're looking to grow, correct?
Claude: That's right. So the other members are Charlie Anderson, who's a professor in biology who studies cell walls, and is interested in the cell wall engineering capabilities of these organisms and what we can learn from them. Mike Axtell studies the molecular biology of these parasites. He's focused on small RNAs and how the RNAs that are being produced by the parasitic plant can travel into the host and affect gene expression in the host. It can shut down defenses in the host, very complex interactions at a molecular level that are just beginning to become understood. This was in a breakthrough paper from Mike's lab just last year. We have Francisco Dini Andreote who's a new faculty member in the plant sciences department and his specialty is the microbiome of plants.
He's understanding what is special about the microbiome of parasitic plants, and how really beginning to understand and manipulate the microbiome of parasitic plants might be key toward controlling them. And we also have Jesse Lasky, who's a professor in the biology department. And Jesse studies the evolutionary genetics of adaptation, and particularly focus on at a population level of how there are differences in genes between host plant populations and parasitic plant populations that can affect their interaction. One gene that he's focused on is a gene called LGS1 that is a gene that interrupts the strigolactone synthesis. Plants that have interrupted strigolactone synthesis are not very good at stimulating their parasitic plants, and they're also less good at bringing in the mycorrhizal fungi. So it's this evolutionary balance between what's good, what's not so good in the complex world that these plants live in.
Cole: Right on. You've got a lot of folks with a lot of great skills that are coming together at this center, it's going to be exciting. And you're looking to even branch out, I heard you talking about maybe even an engineer trying to get somebody ... I don't want to speak too soon.
Claude: We sure hope so. I mean, there are unusual surfaces produced by the carnivorous plants. Parasites have sticky hairs that they use to first latch on hold on to their host. They're these unusual sticky, viscin threads that the mistletoe seeds used to hold on to the plants.
Tanya: And then in carnivorous plants, we have a lot of really slippery structures that prevent attachment of insect feet, if you will, on the plant causes them to slip inside. So there's a lot we can learn from almost bio-inspired design.
Cole: Yes, biomimicry is fantastic. And again, there's the extremes of super sticky or super slippery. All these extremes with these plants very, very cool. Very fascinating. All right, well, we're going to take a break from part two, we'll be back in just a minute with part three. I'm Cole Hons, this is the Symbiotic Podcast. We'll be back in just a moment.
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Cole: Welcome back to the Symbiotic Podcast. I'm Cole Hons here with my colleagues from Penn State who are starting up a new Center for Parasitic and Carnivorous Plants. So for this last leg of the conversation, I just want to find out where do you guys want to go from here now that you've got this center put together and you've started to play at all these different levels and looking at these plants in new ways that no one else is even trying out? What do you want to do with all that?
Claude: Well, one of the really important things we want to do is to try to use this knowledge that we're gathering to try to understand really, not only how do they work, but how can we use that knowledge to maybe flip how they work or interrupt how the parasites work or take advantage of the novel traits that they've evolved and see what they can do?
Tanya: Yeah. So one of those in carnivores. So these plants make these digestive enzymes to break down their prey. And a lot of those enzymes have similarities to those that all plants have like defense proteins. And so one of the things we're really interested in is, can we learn something from the carnivorous plant enzymes that might help make a crop plant more able to defend itself against fungi, and insects? And this has been shown by a few other groups that if you take a carnivorous plant enzyme, and you put it say in a crop plant, that they're better able to defend themselves.
Cole: Interesting.
Claude: One of the other things that we could say is, some we really haven't mentioned yet, which is this flow of information between parasites and their hosts. This is something really novel that's come out of the work, out of our lab, Mike's lab and other collaborators' lab. There's RNA moving back and forth between these parasites and the hosts. There's even DNA moving back and forth between the parasites and hosts, the parasites have large numbers of horizontally acquired genes that they picked up from their hosts and now they're using as part of this battle against their host plants. We want to use the information to try to understand how parasites might be turned off. So if we could use the knowledge of exactly which genes are being used by the parasite, we can engineer and we've done ... we've engineered the host plants to produce RNA that will shut those genes down and will interfere with the development of the parasite. This really works and there are prior publications that show this but they haven't really been put into work in the field yet. So one of our goals ultimately is to try to leverage this knowledge to actual crop plants that are resistant and using this information that these parasites do unique things with the information they've got and the crops have. We think we can be able to use this information to affect the crop plant resistance.
Cole: And so that could be applied to perhaps Striga, which you mentioned before being a major scourge in Sub Saharan Africa?
Claude: That would be a major goal, Striga ... relative to Striga called broomrapes are also a serious problem in other parts of the world, [Cassytha 00:49:31] is a serious problem in many parts of the world. All of these serious problems could be addressed with this kind of information.
Cole: And the other big major goal's moving ... I know you're very young. So I recognize you're just starting to map out what those might be. But I'm always wondering, at Penn State here with the people that we have or certain things bubbling up because of the people that we have in this particular place at this particular time. Tomas, we haven't heard from you on this one. I'm putting you in the hot seat.
Tomas: Well, I think about mistletoe, such you know. And I don't want to turn mistletoes off. On the contrary, I want to have more. So, I mean there are angles that are relevant now like how climate change is ... what it means for, for example for this kind of parasitic plants that are also very mutualistic and important. Something I forgot to mention earlier is that there are entire groups of birds that specialize on mistletoe, they're mistletoe birds and that has evolved repeatedly in different clades.
So, there are mistletoe birds in the Americas in different families like the [inaudible 00:50:46] fly catchers and the [inaudible 00:50:47] which is a beautiful bird, these are jewels of birds and people pay money to go and see them somewhere in the Andes or the Amazon. And there are mistletoe birds in Australia and in Southeast Asia as well. These are animals that you don't see them ... they don't live without mistletoe. And these are very specialized vectors. But otherwise you're going to have the mistletoe without them, but that does have an angle I forgot to mention that is relevant for birdwatchers. That's a big industry. And in part, a lot of birds that birdwatchers want to see in certain regions are mistletoe birds. So from a general global perspective, I think we need also more education about what this type of plant do and how important they are, and what climate change may mean for them and the animals that depend on them.
Cole: Thank you.
Claude: You know, we see parasitic and carnivorous plants both as tremendous opportunities for education. So, who isn't turned on by looking at a carnivore slapping its trap around an insect or watching a time lapse photograph of a parasitic plant growing and growing and growing and overcoming its host and becoming the size of a field? This is a pretty dramatic educational moment. In our group, Mike Axtell has started a freshman research initiative class, where freshmen are brought in and they're taken through an intro biology course, which is completely a lab course. They learn about research methodology, they learn to hypothesize and propose hypothesis that they test in the second semester of the class. Mike is doing this all with parasitic plants. And it's been a huge success. Students are being brought into research labs as a result of this and we see a real difference in the students who enter our labs, if they've been through this freshman research initiative. We can see ways that these organisms can impact not only undergraduate education, but our graduate students, who all will be brought in with more than one advisor, postdoctoral training. We see lots of opportunity for outreach to the public. Our arboretum is a place that really doesn't have enough carnivorous plants.
Tanya: We have one little area of carnivorous plants. We can expand that.
Cole: And there's the carnivorous plants that can be out in the open, right? Because I know that at least one or more of our facilities, you've got to get all suited up before you even get in there because they get pretty dangerous, some these plants. Correct?
Claude: That's our quarantine facility for the research on the parasitic plants. So because of our dean, Dean Kavanagh and the biology department, Penn State invested in a walk-in series of rooms that are sealed, sealed through two sets of locking magnetic doors and reverse flow air where we can work on these dangerous parasitic plants. And this has enabled work on Striga. This has enabled work on these relationships between the genetic variation in the host plants and the parasitic plants. Without this, we couldn't really even touch the Striga here. There are only a few such research facilities like this in the country, really in the world.
Cole: Why Penn State and what's Penn State going to contribute globally? What is what is our opportunity here to to make a real difference with this knowledge?
Claude: I think we have a tremendous opportunity to address this central question from novel perspectives and integrate our approaches across a wide variety of disciplines. This is unusual already. So this is already a very integrative activity but these are fundamental questions about how plants are plants and how plants are not plants and what can we learn and what can we apply? This research effort and this training effort will really address these kinds of big questions and I think solve these important problems along the way like helping to understand how we can control parasitic plants and helping to understand how we can better use the knowledge.
Tanya: Right. And a lot of these carnivorous plants are often in areas that are fragile habitats, they serve as good indicators to the habitat health and so there's other sides to them, too.
Tomas: Yeah, from my perspective. So this is an incredible opportunity. I mean, this collaboration to tackle a central question in evolutionary biology, which is about the evolution of animals in dispersal, [inaudible 00:55:56]. Most woody plants in the world are dispersed by vertebrates. And it's a big question and we know very little about how that trade evolution actually takes place. We don't have examples of that kind of evolution in action. And by having the molecular component and ecological side I think for example the mistletoes we studied that they vary a lot in the [inaudible 00:56:25], in coloration even within and among species, and other traits that are relevant for dispersal because mistletoes are so dependent. Their life goes with it, their seeds have to be taken to a particular location by an animal in this case, birds do a really good job. I think this could be a really good system to tackle some several questions about how this interaction shapes an evolutionary radiation that is massive, is so important to life on land. You see what I mean? So for me that's what I ... my token here.
Cole: Right on. So it sounds like we can run the gamut from just fundamental scientific knowledge and understanding evolution in a richer, deeper way, all the way to applying some of that knowledge to address societal problems like food security, and everything in between by just putting all the pieces together. That's fantastic. Well-
Tanya: That's the place to do it.
Cole: Right on. We are. So thanks, folks. Thanks so much for coming out to talk about your new center. I wish you the best of work. We're going to be watching and checking out everything that comes out of your center. And I just wish you all the best. Thanks again for being on the show.
Claude: Thanks very much.
Tomas: Thank you for inviting us.
Cole: Thank you.