Legumes and Tubers: The Hidden Heroes of Agriculture with Dr. Steven Cannon
The following interview was recorded for the Poor Proles Almanac podcast with guest Dr. Steven Cannon, a collaborator, associate professor in the agronomy department and research geneticist with the USDA Agricultural Research Service. Steve's worked heavily in bioinformatics for crop domestication improvement, with a focus on soybean and other unique crop legumes, including peanuts as well as groundnuts. One of the unique areas that Dr. Cannon has worked on is continuing the work of Dr Bill Blackmon, who you may know from the LSU Research Project.
When he left the program, the research continued at Iowa State University, where Dr. Cannon picked up the torch. We chat about the groundnut and its future, as well as why research stopped on it and where it should be going today.
Andy: Dr. Cannon, thank you so much for joining us. Can you tell us a little bit about your background and how you ended up specializing in legumes?
Dr. Steven Cannon:
Well, I guess my first exposure to them would have been, like many of us you know, eating them as a kid. And then I was also a gardener as a child, working with my grandfather, and then in high school and college I maintained a garden and helped feed our family that way. Then, much later, I went back to school in my mid-30s, got a PhD in plant biology, and ended up working on the sequencing project for the first legume to be sequenced, that's one that we don't eat. It's a relative of alfalfa, but it's used as a model species, and since then I was hired by the USDA to manage genetic data for plant breeding focusing on this group of species legumes.
Andy:
Yeah, your name keeps coming up as I do research in various things, and I was like, I got to reach out, and one area, in particular, is with Apios americana or groundnut. It's kind of got a cult following, and it's got a really curious history because of the breeding work done at LSU. So now there's the LSU you can buy. People are working independently to improve on LSU, and being a starchy root crop that also has the traits of a bean of nitrogen fixation and so on, it offers a lot of really appealing traits to a backyard grower or even from a bigger major crop standpoint. On the surface, it looks like it's very appealing. It has all these really great qualities that we would want.
I don't know if the word inherited is the right word, but you managed to get involved with the continuation of some of that research in Iowa, so I don't know if you could talk a little bit about that.
Dr. Steven Cannon:
Sure. So LSU, Louisiana State University, the people working on apios. First, there were Bill Blackman and his research technician, Berthal Reynolds. In the 1980s, they went around the country, mostly focusing on south Louisiana and surrounding states, collecting apios from the wild. Apios tend to grow naturally near bodies of water, lakes, and rivers, so they collected a lot of varieties, crossed those, and evaluated those crosses for several years.
Bill Blackman retired in the early 90s. He carried some of those improved lines or selected lines with him to Virginia, and some of them remained with Louisiana State. As you said, I did inherit some of that collection. I have a good friend, Gautam Bhattacharya, who contacted Bill Blackman, and then Bill sent me that collection. Then, in 2014 and 2015, I had a student, Vikas Balamkar, who evaluated those lines in a number of different ways.
Andy:
A number of publications resulted from his work lines that were as productive as yams, or at least in terms of weight, which was really impressive and, I think, speaks to the capacity of the plant to maybe be bred more selectively for improvement. So I know you've worked with it quite a bit. At this point, I'm kind of curious about your thoughts on whether or not it has some potential or if maybe there are some shortfalls that may not be as obvious to somebody who just sees that academic data as to why it's not really being continued today.
Dr. Steven Cannon:
Sure. Well, let me give a little background about it. Like virtually all crops that we use, it started as an important crop for Indigenous people. Most of the beans that we use, for example, were domesticated in Central America and South America. Apios is unusual in that it was used as a crop in North America. There aren't a lot of Indigenous North American crops, but Apios is one of those.
As far as we know, it was mostly wild-harvested. There might have been some selection as native groups carried lines from place to place. One bit of evidence for that is that there is a population in the northeast that is probably sterile, but it goes all the way up into the east coast of Canada, so tribes in that area very likely carried it. So, it was used by tribes throughout the eastern half of North America, dug, probably in the fall or spring, along stream banks.
The qualities that they would have valued are the same ones that are valuable now. It's quite productive. It keeps well, so if you're looking for some food in the springtime, when now much else is growing, if you know where to find it, there it is. It's fairly high protein; about three times, three to four times as much protein as a solanum potato. It has a good edible starch content, and it's well adapted here, you know, so it seems to be pretty disease resistant, relatively drought tolerant, tolerant of flooding. So, for all of those reasons, it seems like a great crop. I think it is.
But there are also reasons that it hasn't taken off as a crop. One is that it has to be dug. So a little bit like you know solanum potato, you have to do some work to harvest it. But unlike the Irish potato, I keep calling it Solanum potato because it's not Irish; it's South American stolons, and those tubers might be separated by ranging from inches to a foot or more from tuber to tuber. So you end up having to do quite a bit of digging. That's probably the main reason. That it hasn't been domesticated is just kind of the difficulty in management. Also, it's perennial, so we don't have good systems for the mechanical harvest of underground perennial crops.
Andy:
Yeah, it's a tricky one, God. I can't even imagine a foot-long stolen. I'll harvest them here. I live in New England, and I'll harvest them around a couple of ponds nearby, and I mean when you're out there, and they’re long but not impossible.
Dr. Steven Cannon:
But for some of the longer ones, to follow that stolon takes some effort.
Andy:
Yeah, yeah, it's a little bit like fishing, you know, trying to pull the thread, trying to figure out where it's going without snapping it. I could see how that could be a challenge for breeding. I know that was one of the things that did come up in the papers, identifying specific lines that had shorter stolen lengths, and I'm not sure if you found any correlation, and this is probably getting a little bit into the weeds a little bit but if you did find any correlation between the stolen length and the size of the actual tuber.
Dr. Steven Cannon:
Well, we think that there's a correlation between the length of the above-ground vines and the below-ground stolons.
Andy:
Interesting.
Dr. Steven Cannon:
And that would make a lot of sense botanically, because a stolon is simply an underground vine.
Andy:
Yeah, so the project is, as far as I know, over. So, what's going on with those genetics? Are they just sitting in some storage facility, or is somebody playing with them at all? Is there anything cool going on that might be coming out with these guys?
Dr. Steven Cannon:
Well, I would say there are undoubtedly a lot of cool things going on that I don't know about, just in the sense that, as you pointed out, it's kind of got a cult following, and a lot of people are growing it. So I'm sure that a lot of people are growing it and holding on to the lines that they like best. So, in that sense, I think it's probably following the trajectory of many crops historically. As landraces are selected, people pick their favorite lines and keep growing them. We're not doing much directly here in my group, apart from genome sequencing, which is not trivial. But once we have that genome sequence then it'll make some other molecular studies easier.
Andy:
You've talked about making a soup, and it can taste like boiled peanuts, which I believe you described. I guess you were saying that the genetic split between peanuts and groundnuts happened about 50 million years ago. Do you have any concerns about it as a crop, for allergic reasons or because of its proximity to peanut?
Dr. Steven Cannon:
So it's actually not any closer to peanut than any bean is to peanut. Okay, so the 50 million year, give or take a few million, is probably accurate. Apios is in the group of what's sometimes called warm-season legumes, with lima bean, soybean, common bean, and so on, so it's in the bean group. Peanut kind of sits on its own, quite distantly related to those in the same subfamily in the legumes, but it's an early diverging branch.
Andy:
Gotcha Okay.
Dr. Steven Cannon:
But to your question about allergy, I would say that's something that's not been rigorously evaluated. Yeah, yeah, a stomachache, whether that's associated with the peanut or the preparation, or I mean not the peanut, the groundnut, I don't know. But sorry, if there is some kind of allergenic compound, I would say it's very unlikely to be the same kind of compound as peanut because the allergen in peanut is a seed storage protein. If there's an allergen in brown nut, it's probably something else.
Andy:
That makes sense.
I want to jump into some of your other research as well. You're one of the managing editors of Legume Perspectives, which is a journal that focuses on legumes. Obviously, I stumbled across it because I was doing research about various plants, and there are so many really cool niche crops that are talked about in the magazine, which I really appreciate. Prairie turnip and tuberous pea are two that I have a lot of interest in, and there's, as you probably know, not a whole lot of stuff being written about these types of plants. So when you can find someplace where it's all in one spot, it's kind of a nice little treat to find as the editor somebody who's spent a lot of time with various legumes.
I'm curious about what you think are some more, I guess, underutilized. Like you know, we're talking about how, like, groundnuts have this cult following. What are some of the ones that maybe you're, all this plant needs is the right, like a little bit of funding, and it's going to make this huge step forward like it's almost there kind of thing.
Dr. Steven Cannon:
Well, it's a great question because I do think about that sort of thing a lot. I should clarify that I'm not an editor of that. It's an unusual publication. It's not a standard academic publication with regular peer review. It's kind of a labor of love, kind of a zine.
Andy:
Yeah, yeah, that was the impression I got. I got the impression it was voluntary. This edition, you were the editor for, and there are a lot of legume crops.
Dr. Steven Cannon:
I would say, if you kind of list them all, most people would not be aware of most of them. Lentil, chickpea, common bean, cowpea, pigeon pea, and then you start getting into some less common ones, Winged bean, scarlet runner bean, and then some really unusual ones, and then some of those are ones that we highlighted in that publication. Let's see tylosema or marama, groundnut, and some unusual African legumes. So I think all of these have promise.
In many cases, I think they will be niche crops, as they have traditionally. What I mentioned in passing is a winged bean. That is important in East Asia, and it was domesticated in Papua New Guinea. That's one that I'm quite passionate about. That one happens to have a tuber, but you harvest it first for the young pods or the leaves, and then at the end of the season, you harvest the tuber.
Andy:
Oh wow, and it's an annual, so you can take it all in one year.
Dr. Steven Cannon:
Yeah.
Andy:
How big are the tubers?
Dr. Steven Cannon:
Well, I know this is unfair on a podcast, but here's a picture of dinner. It's okay, kind of the size of your thumb, but the tubers are branched, so it's kind of like it's not like a thumb, it's like a hand, so you harvest, can harvest, a cluster of these thickened roots.
Andy:
Interesting. That actually kind of does remind me a little bit of tuberous pea, the way it grows and it's an annual. How did you stumble across this crop? Is it something that you just found and dug into further, or was it something you'd been exposed to from another researcher?
Dr. Steven Cannon:
I guess since this is this group of plants is of interest to me generally. You know, I hear about it here and there, and you can actually get seed for winged beans in US catalogs. I probably got it from a seed company called Pine Tree Seeds. I think the catalog might have changed its name over the years, but you can find Winged Bean. It's a good crop.
Andy:
Are you doing any breeding work with it or just growing it and consuming it and appreciating?
Dr. Steven Cannon:
it, just appreciating it.
Andy:
Awesome.
Dr. Steven Cannon:
So, to try to answer your question a little bit more directly, you asked if there are species or potential crops that have a lot of potential. I think Winged Bean is one. There are a lot of others that are very important globally that I think are underutilized in the US, and you know they're not uncommon.
But I love growing and eating and cooking with cowpea. It's a faster-cooking bean than the common bean, physiolus vulgaris. It's a little more tolerant of heat and drought or a little more tolerant of heat and drought. Another one that I like that's very common, but I think it has a niche in a warming world with more climate challenges is the lima bean. It's a little more tolerant of heat and drought. It was domesticated in one kind of Mexico, a desert in southwest Central America. One thing I like about both cowpea and lima beans is that they are quite easy to grow, and they're very productive in a small space in a home garden.
Andy:
Yeah, growing up, my parents are from Italy, and one of the things we had growing up was lupini beans, which I'm not sure if you're familiar with them. I'm actually not even sure what their Latin name is because whenever I look up lupini beans, I always see it as a food, and then they never list it. Like I wanted to buy some to grow. I ended up buying some dehydrated ones that I grew, but they were food-grade. They're kind of like a fava bean almost, with a really thick shell that you basically brine, pickle, and then you have to peel off the waxy coat on it.
But, yeah, to your point, there's all these various peas and beans that we really don't utilize, even though they're available. We just, you know, you could say it's the American diet or whatever, but we're not really utilizing them in a way that makes sense, especially, I think, as like this growing movement for no-till and, you know, cover crops and all these other tools to reduce the damages of industrial agriculture, to like figure out how to kind of shift our diet a little bit to utilize the things that we're growing that are more climate resilient, which is, I think, its own kind of challenge.
Dr. Steven Cannon:
Yeah, so lupini beans. I'll mention one other that's unusual in the US but important locally in Europe, including Italy: cicerchia. I’ll talk briefly about those two. The first one you mentioned is lupini. There are several different lupine species that have been domesticated, at least one in South America (Forget the local name) and then a couple in Europe. So there are old-world and new-world lupins.
They are very high in protein. They do well in some soils that other crops have difficulty in, for example, in western Australia, which tends to have lower fertility, droughtier, sandier soils. Lupine has been developed as a relatively new crop so it does well in that agroecological niche and it's just a great food. It is higher in protein than soybean, for example. So I think lupine is one that has a lot of potential. It also has an unusual ability to scavenge phosphorus from the soil in addition to fixing its own nitrogen.
The other one I mentioned that I've seen in Italy and other places in Europe and other places in Europe Cicercia is a common name. Latharus sativus is the Latin name for grass pea it's sometimes called that one. If you harvest it fresh, the seed reminds me of a fresh chickpea, a really good, slightly sweet, slightly crunchy pea-like legume. That one is mostly used as a dry pulse crop, in a soup, for example. Really tasty and nutritious, but that one hasn't taken off because it has an anti-nutritional compound that can be dangerous if you use it as a famine food, that is, if that's all you eat. It can cause a disease or a condition called latherism. That said, that condition is very rare because we don't typically eat foods in exclusion, you know, as a single dietary component. But I think grass pea is another one that has a future.
Andy:
Awesome, it's interesting. I hadn't heard of grass pea, but it sounds promising. Now, one thing you mentioned in that journal, I think it's like kind of one of the main pieces of Legume Perspectives that edition is this idea about why some legumes grow these massive tubers like the ones we've talked about, and then others are just like you know, your typical, like vine, right, they just have a conventional root system.
I think you suggest that, and you can tell me if I'm wrong, a lot of this is driven by inconsistent rainfall and extreme weather, which drives the plant to create this reserve system, almost like an emergency release valve for those dry spells and things like that. Could you speak a little bit more about whether or not that's the case and maybe if the evidence has since changed for you?
Dr. Steven Cannon:
Yeah, well, I think that's a reasonable hypothesis. It's our hypothesis. I'm not aware of rigorous tests of that, but there's a lot of circumstantial evidence that suggests that tubers have evolved multiple times in different lineages in the legumes. For example, there's an early diverging legume species that is an important Indigenous group in South Africa, called Morama bean, and that will produce a gigantic underground tuber that stores water, you know, when an infrequent rain comes in the Namibian desert, and then you know later it uses that stored energy and water to produce the above-ground vine and seed that's harvested so entirely independently.
In South America. You can look at other tuberous legumes, Ahipa grown in the Andes or the related jicama that we, you know, purchased from the grocery store here. Both of those are tuberous legumes, and I think that those have that characteristic, ecological characteristic you mentioned: dry, mountainous environment, pretty harsh, the plant has to go dormant sometimes. You know, one other from Central America would be Scarlet Runner Bean.
That's fairly closely related to the common bean; it's in the same genus, but the scarlet runner bean also produces an edible thickened root, and like most of the beans from Central America, it grows in an area that's periodically dry, and those beans not only have to sort of wait out dry periods, they also have these vines, so when the conditions are right they want to be able to climb nearby vegetation. So they have to get that stored energy from somewhere.
Andy:
That makes sense. I mean, to me, that whole theory does make a lot of sense when you think about those crops. The only one, I guess, really is groundnut. That wouldn't fit that kind of convention, oddly enough.
Dr. Steven Cannon:
It might in a slightly different way. I mean, it's probably not typically limited in terms of water, but its growth strategy is a vine, and it wants to climb nearby vegetation in the spring.
Andy:
Yeah, well, that's true, it does shoot up pretty quick. Yeah, that's interesting. Now I up pretty quick. Yeah, that's interesting.
Dr. Steven Cannon:
Now I'll mention one more just to kind of fill out that pattern. Go ahead, and this one has a very sort of deservedly bad reputation in the US, but that's a kudzu problem in the South. But in East Asia, in Japan for example, kudzu is used as a crop because the starch is edible and valuable. So if you can harvest the tubers you can use those as well. But that's a problem in the US because in a new environment, it's kind of taken over, and it rapidly climbs whatever it can climb.
Andy:
Yeah, it's done a little bit of damage. We could probably do some damage back if we'd eat it, but we haven't figured that one out yet. So I guess the last thing I want to bring up, and you've kind of hinted at this already, is the role that climate change is playing in how we think about crops and how we think about what our future food system looks like. You know that it might not be in our lifetime, but in the next couple of generations, our food system is going to have to look probably fairly significantly different, and I think that some of these plants that we haven't spent as much time learning as a species may have a role in that, and I'm curious if there's any in particular that you think are uniquely capable of dealing with some of those extremes that climate change is probably going to force us to learn to grow food under.
Dr. Steven Cannon:
Yeah. So let me give three answers to that. One would be something we touched on the lupins that have been sort of newly domesticated, or at least species have been domesticated for growing in new environments, that is, in Australia. So I think there's room for pretty dramatic crop improvement for things that might be crops now but can move into new niches. Lupin would be one. I mentioned winged beans.
Winged bean is a nice crop right now, but it's limited in a little bit in that the growing season is quite long, and the pods become fibrous as they get older. You might say well, don't most pods, legume pods, get fibrous as they get older? Well, yes, probably. But that can be selected or bred out. If you think of edible pod or snow pod peas, that's not the wild type character. That's a character that actually Mendel described as one of the traits that he was studying its genetics, of a parchmentless pea. Imagine various parchmentless beans pea, imagine various parchmentless beans.
Okay, so that's the domestication of kind of existing crops. Another part of the answer could be finding uses for resilient species that we've not thought of as crops to this date. One I'll mention there hungama. I actually don't know the common name, but it's a species that's native to India, a tree species, so, being a tree, it's sort of inherently perennial. The part that's harvested is the pod and the seed, and that's being investigated, actually, by a company that focuses solely on domesticating and using pongamia as an oil seed, and that's being grown in well in India, Australia, Florida and semi-tropical areas.
Andy:
Yeah, it looks like it's called Pongame oil tree, which is the common name.
Dr. Steven Cannon:
So the challenge there? I guess there's a breeding challenge and also a preparation or utilization challenge. The seed has some toxins, but if those can be removed, either through genetics or through processing, processing, then it's.
Andy:
You know, it's potentially an important food. Yeah, that's something you, uh, we'd email back and forth about Kentucky coffee tree as being a potential for similar reasons.
Dr. Steven Cannon:
Yeah, it's a hardy, productive tree in North America. Yeah, the third part of the answer I would give would be existing crops that I think we could just use differently and better.
That's a characteristic of a lot of landrace crops: they're indeterminate crops. So I think people could grow them in backyards or available farmland on a small scale, and that would provide a lot of resilience and health in their own diets.
Andy:
I think of different ways that we can try to address some of these challenges because it's a big one and like I said, it may not be in our lifetime, but at some point the continuation of the way climate change is moving our food system and so on something will have to change, and making sure that there are the resources to begin that process of change is always important yeah, well, I mean, of course, climate change totally is in our lifetime, and I think that the hopeful aspect of on the plant side is that I think the solutions are all also at hand.
Dr. Steven Cannon:
You know. So, growing things yourself, learning how to grow them, growing a lot of different things to become more experienced in what works and what doesn't for you, that's something that all of your listeners can do next year.
Andy:
Yeah, absolutely. If you're listening and you want to grow any of these things, check them out there: a diversity of delicious legumes. I mean, you know how you go wrong with a root crop. Everyone loves potatoes, and then add groundnuts to it. Add some of these other things, prairie turnip, tuberous pea, and you've got some really cool stuff to work with, and you can make a lot of cool, really fun, exciting foods with them.
They are some really cool stuff to work with, and you can make a lot of cool, really fun, exciting foods with them. So, from a legume perspective, are you guys still planning on it? Do you expect another zine to come out in the next year or two, or is it kind of a when it happens, it happens?
Dr. Steven Cannon:
Honestly, I don't know the frequency. I think twice a year, and I'm not sure what the next issue is going to be about.
Andy:
Gotcha, yeah, okay, anywhere that for people that really want to learn more about beans and legumes, you would send them to Just, would it be that journal or anything else?
Dr. Steven Cannon:
There's so much online now, I think a nice entry might be from a cooking angle. You mentioned lupini beans, for example, or pick your favorite legume, lentil, chickpea, and so on. For any of those crops there's actually quite a diversity and a lot of different cuisines that have developed around them. I don't know as someone who likes eating and likes cooking.
I just find that an accessible way of connecting with any of this stuff, how to find out about new legume crops or unusual ones. Seed catalogs can sometimes introduce you to new things. There are some nice books. There's Beans by Ken Abuleta, I think. Specialty seed crops like Southern Seed Exchange is a nice one. Some books Gathering the Desert. That'll talk about things like honey mesquite, a native crop in the American Southwest.
Andy:
Yeah, yeah. Once you start digging, there is a lot of cool stuff out there. Dr. Cannon, this has been fantastic. Thank you so much for your time.
Dr. Steven Cannon:
Happy to be able to talk about it with you.
To listen to this episode, tune into episode 255 of the Poor Proles Almanac.