Plants, People, Science

Dr. Ryan Contreras: Breeding Plants to Prevent Invasiveness

• American Society for Horticultural Science (ASHS) • Season 2 • Episode 6

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Join us for a rich discussion with our distinguished guest, Ryan Contreras, a leading expert in ornamental horticulture from Oregon State University. Ryan shares his incredible journey from the fields of eastern North Carolina to becoming a renowned professor, revealing pivotal moments and key mentorships that shaped his career.

Step into the world of invasive plant species and biotechnology with Ryan as he unpacks the significant ecological threats posed by plants like Scotch broom and English ivy. Learn about the origins and impacts of these species and how new biotechnological tools like CRISPR are revolutionizing plant breeding. Ryan's insights shed light on the potential of precision tools in maintaining desired plant traits while eliminating undesirable ones, making this a must-listen episode for anyone passionate about plant science and environmental conservation.

Explore groundbreaking developments in drought-resistant plant varieties and the collaborative efforts in bioinformatics and genomics aimed at tackling climate change. Ryan discusses his innovative work on Hibiscus syriacus and other ornamental plants, sharing the excitement around new technologies like the Plant Array system for drought stress evaluation. This episode promises to inspire and educate, offering a glimpse into the dynamic and ever-evolving field of plant science through the eyes of one of its most dedicated experts.

See below for more information about Ryan Contreras and his work:
https://journals.ashs.org/hortsci/view/journals/hortsci/47/9/article-p1210.xml
https://journals.ashs.org/hortsci/view/journals/hortsci/57/4/article-p558.xml
https://www.youtube.com/watch?v=FxRnV4cDhT8&ab_channel=OregonAgricultureintheClassroom

Learn more about the American Society for Horticultural Science (ASHS) at https://ashs.org/.
HortTechnology, HortScience and the Journal of the American Society for Horticultural Science are all open-access and peer-reviewed journals, published by the American Society of Horticultural Science (ASHS). Find them at journals.ashs.org.

Consider becoming an ASHS member at https://ashs.org/page/Becomeamember!

You can also find the official webpage for Plants, People, Science at ashs.org/plantspeoplesciencepodcast, and we encourage you to send us feedback or suggestions at https://ashs.org/webinarpodcastsuggestion.

Podcast transcripts are available at https://plantspeoplescience.buzzsprout.com.

On LinkedIn find Sam Humphrey at linkedin.com/in/samson-humphrey. Curt Rom is at https://www.linkedin.com/in/curt-rom-611085134/. Lena Wilson is at https://www.linkedin.com/in/lena-wilson-2531a5141/.

Thank you for listening!


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Curt Rom:

Welcome to Plants People Science, a podcast of the American Society for Horticulture Science, where we like to talk about all things horticulture. I'm your co-host, Curt Rom University, professor of Horticulture at the University of Arkansas, and joining me today is our co-host, Samson Humphrey. Welcome, Samson.

Sam Humphrey:

Welcome, Curt. How are you doing?

Curt Rom:

I'm doing real well. It's another great summer day.

Sam Humphrey:

I made the first homemade lemonade I've ever made in my life this week and it was really incredible. It's getting hot here. It was very, very necessary.

Curt Rom:

It's getting hot here too. You know, I was thinking about our former co-host Lara last night because I was making basil pesto and Lara was working at Rutgers on fungus resistant basil. So now, whenever I have basil in my dinner or in my salad or I make pesto, I think about our former co-host.

Sam Humphrey:

See, I have the opposite problem. When people think of strawberries, they think of me, and so they always send me strawberry texts. But I'm at the very tail end of my master's, and so every time I see the word strawberry it's a little bit grating on my brain. I've written it too many times. I hope you don't feel that way, though, craig.

Curt Rom:

No, you know, I still love strawberries and I still think highly of you, but I can make the difference.

Sam Humphrey:

Just avoid saying the word around me, please.

Curt Rom:

I'll avoid. You know strawberries and you notice I never ask you how's your thesis coming along?

Sam Humphrey:

I. You know, Curt, I appreciate so much about you. That's just one of the many, many things that I love about our friendship. It's going well. I am in the last month of it, and so I'm trying to relax a little bit.

Curt Rom:

I made the lemonade.

Sam Humphrey:

I made cookies this morning and I will make cookies this afternoon. What have you been up to?

Curt Rom:

Well, you know, again into the midst of summer at work, I've got some field experiments and a greenhouse experiment, propagation experiment on elderberry that I'm doing, and then my apples in the field and watching some other projects that I'm collaborating with. My major hobby, as you know, is home gardening, and so my vegetable garden has been plagued with a little bit of excessive drought and not as good as I would like to say. I'm not going to brag on my vegetable garden. My flower gardens are doing reasonably well. I've got my rabbit problem under control and my Japanese beetle problem under control, but my flower gardens are doing very well right now.

Sam Humphrey:

All our listeners with rabbit and beetle problems are cursing you for your rabbit and beetle success. That is something to brag about. Well done, Curt.

Curt Rom:

Okay, I guess we probably ought to get into our conversation today. I want to welcome our audience. Glad that you're joining us today.

Sam Humphrey:

Our guest today is Ryan Contreras. Leading up to the ASHS conferences, I'm reflecting more and more on my experiences at previous ASHS conferences and I actually met Ryan through one of my experiences at previous ASHS conferences, and I actually met Ryan through one of those experiences. He was talking about research and mentorship philosophies, and our guest today is just a really wonderful person. You've actually known him for a long time, haven't you?

Curt Rom:

I've known Ryan since he was a graduate student, and he's just a rock star in the ornamental world, so it's going to be a real honor and delight to have him as our guest today.

Sam Humphrey:

Introducing Ryan Contreras. Let's give the interview a listen.

Curt Rom:

Welcome, Dr. Contreras.

Ryan Contreras:

How are you doing today? I'm fantastic, Dr. Rom.

Curt Rom:

Thanks for having me Well we're glad to have you here.

Ryan Contreras:

Before we get started on today's conversation, how would you like us to refer to you Dr Contreras or what's your preference? Ryan is very comfortable with me. You know I tell my students you're welcome to call me Ryan if you're comfortable, or Dr Contreras if you prefer formality. The only one I don't really like is Mr Contreras.

Ryan Contreras:

You know we worked really hard for that doctorate, so but Ryan, ryan will do just fine, okay, ryan, and you can call me Kurt, and of course, I'd like you to meet our co-host, samson.

Sam Humphrey:

Hey, Ryan, I'm so happy you're here, hey thanks for having me.

Ryan Contreras:

Good to see you.

Sam Humphrey:

For the listeners who for some reason don't know who you are, could you please introduce yourself? What do you do?

Ryan Contreras:

So I am a professor, I'm at Oregon State University in the Department of Horticulture and I am an ornamental plant breeder. I've been here since December of 2009. So, for folks not familiar, oregon State University, we're the orange and black one north of University of Oregon, so we're the beavers and we're located in Corvallis, oregon, north of University of Oregon.

Sam Humphrey:

So we're the Beavers and we're located in Corvallis Oregon which is in the Willamette Valley, western Oregon, about an hour and a half south of Portland.

Ryan Contreras:

How'd you end up there? How did you become an ornamental plant scientist? Yeah well, how did I become an ornamental plant scientist is? You know I have what I feel like is a bit of a circuitous route, not not compared to some folks, but I actually. So I'm from eastern North Carolina and I went to NC State.

Ryan Contreras:

I started in 1996 and I actually started my education wanting to be an ag ed teacher. So I started with ag ed and extension and a concentration in horticulture. So my my goal at that time when I started was to go get my degree and then move back to Beaufort, north Carolina, and run the ag program and start a horticulture program, because we had a greenhouse there but it was essentially a storage place and we used it for a petting zoo once a year but no horticulture was being done. And I knew I did know that I wanted to do something with plants and I liked horticulture. I during my first year I was taking animal science and metal shop and I took my first horticulture class with Bryce Lane and Bryce is one of the most charismatic teachers and one of the best instructors that has ever walked the planet and mine is a common story that you know.

Ryan Contreras:

After that I was less interested in agriculture, writ large and really. So I came to horticulture, transferred in or changed majors into horticulture and was in the standard sort of production option. And you know, I went through and I took a broad suite of classes and during my senior year I went and did an internship at the Center for the Study of Early Events in Photosynthesis at Arizona State University with Ken Huber and it was a really fascinating internship where we were radio labeling protein constituents and looking at what you know the light, harvesting complex proteins whether they were assembling in the thylakoid or you know how, how these essential proteins that are the core of life, where they were assembling. And nobody had answered these fundamental questions before and I was just so blown away by that and it was an amazing opportunity to learn new lab skills and gain a little bit of a scientific acumen. I had an opportunity to present to folks who had been studying these, had been studying this, these types of things, for 40 years and I learned all of those things.

Ryan Contreras:

But what I learned more than anything was that I did not want to be a solely a lab scientist for the rest of my life. I was in the desert, the valley of the sun, and spent eight to 10 hours a day in a windowless room, you know doing doing working with a Clamidomonas reinhardii, which is a photosynthetic algae. So so I came back and, you know, during during my senior year, I was, I, I I ran out of a scholarship that was from my high school. It was a four-year scholarship. So at the termination of that, which was 2000, I took about nine to 10 months off and worked in pizza places, worked in sandwich shops, but I most distinctly remember I did a lot of landscaping off and on.

Ryan Contreras:

But I most distinctly remember it was August and in Raleigh, in the red clay and the heat of August, and I was digging a French drain and I looked over and the rest of the crew was standing there, you know, chewing tobacco, drinking Mountain Dew in the shade, and I was digging a French drain and I was 19 hours from having my BS in horticultural science. So I pulled out my phone and I called the owner of the company and I gave him my two weeks notice and I went back and got to finish in my 19 hours that I had to go and during that time was when I it was really a that was an inflection point. So during that last term I was there, I took plant propagation with Denny Werner. During that last term I was there, I took plant propagation with Denny Werner, of course as a legendary peach and ornamentals breeder, and during that, during that time, well, I learned you know, that could be an hour and a half conversation just on what I learned about being a human and being a scientist from Denny.

Ryan Contreras:

He's one of my great mentors. But but during that time I told him that I wanted to do an independent research project and I'm really interested in woody plants. I've gotten interested in genetics and would really like to do some independent study project and he put me on a project to do chromosome counts in honeycomb buddleia and so in that process he introduced me to Dr Shamal Rao-Tallery, who is a cytogeneticist in the peanut cytogenetics program at that time and so I went over and you know we Dr Tallery started training me and you know root tip collection and we started going through the whole process and I was moderately successful in my work on.

Ryan Contreras:

You know I got some decent enough counts to show them to Dr Werner that you know it doesn't seem to be a triploid. And so anyway, it was that part of it was moderately successful. Denny was satisfied enough and so I got my independent study credit. But what it did is it launched me with Dr Tallery and so I actually stayed on with Dr Tallery working in the peanut cytogenetics program for two years and during that time it was incredible. I got to start doing rapids and AFLPs and we were doing traditional crosses, we did some ploidy manipulation in wild species of peanuts, trying to intergress, disease resistance and insect resistance, and it was just, you know, a full development of all of these skills simultaneously and you know field technique and just so many good things. And it was just a really marvelous time to be in the peanut breeding and cytogenetics program. It was a yeah, sort of a heyday, I think. And you know some of the people I got to work with Tom Islub, suzanne Amelia Lewis, who's now a turf breeder at North Carolina State. She was a graduate student then and sort of held my hand through a lot of my own graduate work that I later did.

Ryan Contreras:

But anyway, but I distinctly remember we were in Lewiston, north Carolina, doing disease screening and Lewiston is well, all of eastern North Carolina is flat. But I remember standing in the middle of a field we were doing disease screening and I turned to 360. And there was peanuts as far as the eye could see, and I'm a horticulturist was peanuts as far as the eye could see and I'm a horticulturist. And that was sort of that same digging a French drain kind of a moment where I then I went back to Danny Werner and I said, hey, I think I'm ready to be back into horticulture and I would like to start breeding some woody plants. Do you know of any opportunities? And he said, oh, I think this guy. And he said I think this guy Tom Ranney has, you know, I think he's got an assistantship coming up. And so I looked him up, sent him an email and he graced me with an interview and again, never forget this that I was about 20 minutes late to meeting with one of the greatest ornamental plant breeders on the planet, because I was loading a gel to run a rapid for the 268 base pair marker for the resistance that we were looking at in these peanut populations, and Tom has also not forgotten that.

Ryan Contreras:

So anyway, I got on with Dr Ranney and what I will say if there's students that are listening what I will say is those experiences. It's not the coursework. He looked at my coursework and he did ask me why did you have such a bad grade in quantitative chemistry? I didn't really have an answer for that, but what was of more interest to Dr Ranney was the two years that I spent in a breeding program, learning all of these real world applicable skills and breeding technique and, you know, related to that. I wouldn't have known how to answer this question, but he asked me what kind of work do you want to do? What kind of project do you want to be involved in? And because of all those you know, the extensive skills and or the experience of being in a breeding program I was able to say you know, I would like something that I can do some traditional breeding. I'd like to make some crosses, try to do some improvement. I would like to continue doing some cytogenetics. I really like, you know, ploidy manipulation and I like ploidy analysis. And then I would like to do something that has some molecular component. I'd like to, you know, use some markers and do something along those lines. And I think you know the combination of having two years with the peanut genetics program and the ability to come in and, you know, say these are the types of things I want to do in a project is why he took me on, even though I showed up looking like a rag muffin and I was 20 minutes late and I had a C minus or something in quantitative chemistry. So anyway, that's how I got on with Tom and of course his program is he's one of the best graduate advisors, you know that's ever been and really helped launch me. And it also, again, one door opens another, and so you know my success.

Ryan Contreras:

I worked hard with Dr Rennie and was then recruited by John Reuter out of University of Georgia, was then recruited by John Reuter out of University of Georgia, and that was a really fun time to be with Dr Reuter because he was really transitioning from being one of the best nursery extension agents that's ever been to really transitioning more to germplasm plant evaluation and getting into plant breeding more heavily. But was really phenomenal that he, he, I went down to Tifton after I did my coursework in Athens and I went down there and he just, you know, he kind of opened the door, you know when. When I got there, he said you know, I want you to do there's. There was two projects he said I'd like you to do these and both of them were chromosome doubling projects on some plants he was working on. So but other than that, you know, I don't care how you do it and I don't really care what else you work on, and he had, you know, hundreds of genera down there and it was really fun. It was just like a kid in a candy store, like you get to do whatever you want, and so it gave me a lot of free reign.

Ryan Contreras:

I spent a lot of time failing, had some successes and got to work with amazing folks. Peggy is Isaiah Aikens, who is. You know, what do you say about Dr Isaiah Aikens? She's a brilliant scientist and even though she is an exceedingly kind person, her brilliance is intimidating. But so she works on apamexis and in a few different crops, and Wayne Hanna was also a key member of my graduate advising team down there and neither of them work on ornamental plants. So that's something else I would like to tell.

Ryan Contreras:

You know, if there are students that are listening, don't just look within your field. So, if you're a grape breeder, don't just look at at grape breeders or grape geneticists for help and guidance. Um, you know, make sure you're looking throughout, uh, not just the horticultural discipline, but, uh, crop science and botany and plant pathology or wherever it is. So anyway, that is a very long way of saying how I became an ornamental plant breeder.

Ryan Contreras:

I was, I was fortunate enough and I think timing is a lot of timing is everything when I had taken my prelims, but I was still a year and a half away from defending and this position came open and I you know you have to you got to shoot your shot. So I applied and I think I was fortunate that there weren't there, apparently was not a a whole cadre of folks coming out of their PhD who were interested in woody plant breeding in the Pacific Northwest at that time. So I was very fortunate enough to be offered this job and they waited for me to finish writing my dissertation, defend and drive out here. So that's my very long story of how I came to Corvallis and I can tell you there's not that's an interesting story, thank you. There's not many places that are more on opposite of poles than Tifton, georgia, and Corvallis, oregon. I can tell you that.

Curt Rom:

Well, you're in the heart of one of the most diverse and intense nursery systems in the United States, so it's kind of a great place for you to land. So, at Oregon State, tell us what do you do, what are your responsibilities? You obviously research, but do you have teaching extension? Tell us a little bit about what you do.

Ryan Contreras:

Yeah, my, my job has evolved a little bit over the years, as many of these are want to do. So I was hired at a pretty heavy teaching appointment. When I was hired, I had lots of different aspects, but what it came down to was about 45% teaching, 55% research, and then, of course, there's service in there and things, and so I was teaching plant identification in the spring and the fall, and we're on the quarter system here in Corvallis, so we have spring, winter and fall quarters here in Corvallis, so we have spring, winter and fall quarters. So in the spring and fall I was teaching plant identification, and in the fall I was also teaching a plant growth and development course and over the years I picked up plant propagation. So then I was teaching four classes on campus, and also in 2011, anita Azarenko, who's the former department head and former vice president for ASHS.

Ryan Contreras:

She was a visionary and launched the first in the country eCampus degree, so I started teaching all my classes by eCampus and, yeah, so at one point we had I had nine sections of teaching that I was responsible for, but we transitioned that, so graduate students and other faculty here in my under my banner are taking those on. Yeah, so I've actually tried to taper down my teaching a little bit. So I'm trying to just stick with plant propagation and plant growth and development. But in 2021, I picked up some administrative role. So now I am research teaching and I'm the associate head for horticulture. So you know, all of those things keep one busy.

Curt Rom:

Yeah well, thanks. Yeah well, careers evolve over time. You know we're evolutionary in our academic pursuit, but thanks for sharing that.

Sam Humphrey:

So we reached out to you because you've recently published a paper called Genetic Methods for Mitigating Invasiveness of Woody Ornamental Plants Research Needs and Opportunities. This is a fantastic paper To get started on this topic. We were curious if you could talk to us about what invasiveness means. We were talking with someone who's not a plant scientist but who listens to the podcast and she was saying invasive, native, non-native. What do all these terms mean? Could you give us the very basics of this?

Ryan Contreras:

Yeah, you know, that really depends who you ask what invasiveness is. I can tell you that the definition that we like to use, that I like to use, you know, invasiveness is a plant that develops or spreads on its own accord. So without human intervention, it spreads of its own accord such that it forms a monoculture and displaces all other flora in the same location. So if you've ever seen scotch broom here in the Pacific Northwest, himalayan blackberry will do this. But in the South and actually here, english ivy is maybe the worst, where it just completely covers a dug fir and will crowd it out and kills the dug fir. And in the Southeast you've got Chinese privet. It's a pretty notorious one. Japanese honeysuckle is another one that covers millions of acres.

Ryan Contreras:

People think about invasive plants as being non-native and that generally I would say most of the invasive plants that we have that we consider invasives and all of those ones that I just mentioned are non-native plants as well. But we do have an interesting conundrum here in Oregon and the West with western juniper. So because of fire suppression, western juniper has started running rampant and it truly has become invasive and it's because it has a deep taproot and these, these areas that were previously grasslands and it's dropping the water table, so it's it's it's now exacerbating and it's dropping the water table, so it's now exacerbating. You know the drought situation, so you know, yeah, so I think. An invasive plant. It causes ecological and economic harm, displaces other flora.

Curt Rom:

That's real interesting. We actually have a native juniper problem as well too, when we clear cut forests, et cetera. You know there's some great stories about invasive plants and I want to get kind of get back to that. Where do these invasive plants come from? I mean, are they accidental immigrants or are they introduced? I particularly think about the story of Caloriana pear, which there's a link to Oregon State University, and the first report of escaped Bradford pear mythologically occurred in my state, arkansas, two years after the Bradford pear was released by the USDA. Where do invasive plants come from? And you know, what role do we have as scientists about this have?

Ryan Contreras:

scientists about this. Yeah, you know, I don't want to pretend that I know. You know everything there is to know about where all of them have come from. But you know, ornamental horticulture is certainly a it's got a black eye from introducing plants. The thing is not to get too preachy on it. But you know we have this built landscape that's not native, and so we've introduced plants that are going to be resilient in a concrete jungle where there's poor soil, low soil volume, and so we ask plants to not just survive but to thrive in these environments, and we want them to flower, we want them to fruit, we want them to be beautiful and do all of these things for us, and some of them do it exceedingly well, and they do it to the point where they are so successful that they then escape cultivation. But as far as you know where they come from, I mean, a lot of our flora comes from Asia, from, you know, southeast Asia, eastern Asia, uh, asia, from. You know, southeast Asia, eastern Asia, um, you know a lot of invasive plants are from from China, but that's, that's not. That's not it. You know, uh, we have some. You know, prunus loris racis, I believe you know it's from the caucus region. Uh, and it's been, uh, it's become quite a bit of a problem here in the Pacific Northwest, escaping cultivation English ivy is uh.

Ryan Contreras:

So I don't think there's simply one location, I think you know, related to invasiveness. There's what's called the rule of tens, and so one in 10 plants will survive without human intervention and it might, you know, a seedling here or there. One in 10 of those will form a naturalized population that, will you know, survive and it will then become part of the biodiversity. It's not reducing biodiversity, actually, if it's naturalized but not displacing, it actually is increasing the biodiversity. But then one in 10 of those actually becomes invasive. So essentially, one in a thousand plants that we introduce is going to become invasive. Plants that we introduce is going to become invasive. And simply just on the probability, we introduced so many plants from Asia that most of our invaders come from Asia. I don't know that there's anything inherently invasive about Asian plants, it's just we've introduced a lot of them and some of them have taken hold.

Curt Rom:

Well in our reading, since you say they come from Asia. I know early plant exploration by the USDA occurred in Asia and China, in a large part because they thought that the climate was so similar to the United States, and so a plant that would be adapted in parts of Asia would readily be adapted to the United States. And it's interesting, just kind of, from the story you told us there. I guess it's the unintended consequence of good intentions.

Ryan Contreras:

Absolutely yeah, and you're right. Yeah, you know, plant hunters have been really savvy and go into climate appropriate regions to search for. So when, when Dr Reuter was down in in the, the forgotten zone eight of Tifton, he likes to call it, he was really interested in Taiwanese plants. Right, very similar climate, hot, humid, and and he found a lot of cool plants that we hadn't grown in the United States that he brought in from Taiwan. So, yeah, that's fascinating.

Sam Humphrey:

So there are lots of reasons that plants can become invasive, lots of traits they can have that can make them more likely to become invasive. I study strawberries in my master's research and I've never thought about how plant breeders try to make plants better for people, try to make plants that grow well, but how that can actually lead to them becoming maybe invasive. What can plant breeders do in the opposite direction to maybe prevent invasiveness?

Ryan Contreras:

Yeah, you know there are a number of different techniques and you know that paper you mentioned where Kelly Bining was the lead and Steve Strauss. It's due for an update. Due for an update for sure. But you know there's a number of ways. Wide hybrids, you know, you cross a horse and a donkey, you get a mule and that's a breeding dead end, but it's a very useful organism and so that's one of the approaches that we're trying is wide hybridization. You can also use mutagenesis, right. So you just point the shotgun, whether it's a chemical like ethylmethane, sulfonate or gamma radiation, and you just try to knock stuff out. And we've successfully done that in a couple of different plants. Haven't commercialized anything yet, but that's a very shotgun approach. And then you know, on the very opposite end of that is, you know, precision biotechnology, you know using things like zinc, finger nucleases to go in and do floral ablation and you get rid of the floral parts, right, you get rid of all of the anthers or get rid of the pistol, and you just create a plant that has nothing but petals. And there are a number of examples of just selecting four plants that have increased petaloid stamens or petaloid reproductive structures.

Ryan Contreras:

What we have done mostly in my breeding program is using ploidy manipulation. So we're changing the number of sets of chromosomes that a plant has to render them seedless, and this is the same technique as in bananas. So bananas are a triploid. They've got three of the A genome in Cavendish banana. And what's interesting about that technique is it is highly variable depending on the plant that you're working with.

Ryan Contreras:

So in some plants, like in banana, it seems to be ironclad. I have never chipped a tooth on a banana seed, so you never see a banana seed. But then you know, in plants like apple. So gravenstein apple, gravenstein red apple, is a triploid. But if you cut it open there are seeds inside. And so some plants it doesn't seem to render them completely seedless. Some plants it does.

Ryan Contreras:

There's a really great paper from Tom Ranney's lab with Whitney Phillips as the lead author on, and it looked at different populations of triploid flowering pears Speaking of that, dr Rahm mentioned calorie pear and some of the triploids were virtually sterile and then others were not that greatly reduced at all. So those are the main techniques that are at our disposal. The challenge with the biotechnology thing is, you know, it requires reliable sequence, information and regeneration methods that we don't have for most of our woody plants. But as sequencing goes down and methods of gene editing and introducing those yeah, the gene editing tools into the plant, changes where it no longer requires potentially going all the way to a callus and then regenerating a plant, so I think the future is exciting for using those more precision type tools.

Curt Rom:

So I think the future is exciting for using those more precision type tools. So you believe techniques like CRISPR, where gene editing is kind of the new frontier on this, and a technique as opposed to more that shotgun approach of mutagenesis that you were talking about?

Ryan Contreras:

I do. I don't think it's going to completely replace it, because I think you know, on the one hand, using precision tools like CRISPR and other biotechnology tools are really useful, because I can take a genotype, potentially that we want to maintain that exact phenotype and we don't want to change anything about it other than just getting rid of seed production. So that might be a great opportunity there. But then, on the other hand, sometimes you know, as plant breeding isn't that complex, it's just selecting something better from a variable population, well, maybe we want to introduce some more variation. So I think that shotgun approach to continue creating more variation from which we can select is going to continue to be useful. But I mean, I we're really excited we have Beth Rowan is going to be starting as a new biotechnology assistant professor in our department this summer and all of us who are doing plant breeding are excited to try to ride on her coattails and bring some of those tools into our crops.

Curt Rom:

Of course, I suppose for something as specific as gene editing, you then have to have a map editing, you then have to have a map, and so there's a lot of kind of backstory work before you can get to the product of that. So that's kind of cool stuff, absolutely yeah.

Sam Humphrey:

But when you do get to the product, I wonder if you reduce fertility, does that make it more challenging for nurseries to grow and to sell these plants?

Ryan Contreras:

You know, from the standpoint of propagation. Is that what you mean?

Sam Humphrey:

I'm imagining if you're trying to sell the plant to the general public, but actually, yeah, I guess the issue would be in propagation.

Ryan Contreras:

Yeah. So there's a couple of things there. One you know regarding the general public, I can tell you that the education efforts in something like a Bradford pear and Norway maple have been very good. People love to hate a Bradford pear now, and so they think anything that is a flowering pear is horrible, it's abhorrent and it you know, you should be locked in prison for growing it. And similarly, in the New England states where Norway maple has become highly invasive and upper Midwest people hate it and they love to hate it.

Ryan Contreras:

The problem with Bradford pear people think that it was introduced to be sterile. Well, it never was sterile, it was only self-incompatible and so, as Dr Rahm said, shortly after it was introduced, there were other genotypes that were introduced. And then there we go. We need to educate the public and we need organizations help like American Hort right, and we need organizations help like American Hort right that can help. The name is chastity and not only is it an inner specific hybrid, it is an, an interploidy hybrid, that's, it's a triploid. So it is, and it's been completely tested in the presence of all of these fertile pollinizers over many years, both in North Carolina and at J Frank Schmidt and other places.

Ryan Contreras:

What we're doing now with breeding and introducing plants is very different than you know, just introducing something that's self-incompatible, so that's part of it. So, yeah, it is a challenge to introduce a plant that is now seedless through breeding but the public still sees, you know, as being terrible. Just personally, I plant seedless butterfly bush in my garden, but the education here has been very good. So I've got neighbors who walk by my front garden and they say I can't believe you're planting these weedy invasive plants out here and I say no, I promise you. My graduate student actually tested these for about three years and we know that they produce little to no seedlings. But on the propagation side, the good news is we clonally propagate virtually all woody plants and so there's no we. If they're completely seedless, that's great. We either use tissue culture, cutting propagation or some other method that doesn't require seed.

Curt Rom:

Well, ryan, we've talked about a number of plants, but tell us about some of the species you've worked on. You've worked on fruit trees, acer species, maple species. Tell us about some of the plant species that you've worked on to kind of address these problems, and some of the breeding work that you've done, the various kinds of species that you've worked with.

Ryan Contreras:

Yeah, so folks may not know that Oregon is the third largest nursery producing state, behind California and Florida. But obviously or perhaps not obviously it's a very different environment here and we are big in woody plants, but, nurseries being highly diverse, we work on in some degree. We work on almost 50 genera. That doesn't mean we have large projects on 50 different genera. Most of them are rather small mutation, breeding, making a cross here, there and evaluating and so forth.

Ryan Contreras:

But we've done good work, I think, on Hibiscus syriacus, widely adaptable sort of tropical feeling plant, but is adaptable zone five to nine. So we've been doing ploidy manipulation there. Naturally occurring tetraploid means it has four sets of chromosomes and we now have a ploidy series from four, five, six, seven, eight, nine, 10. And we've been evaluating the fertility or the seedling production across that ploidy series and we introduced one plant in 2022 that recently secured a patent. That's a Hibiscus syriacus and the trade name is a petite pink flamingo. So we've introduced that one. We've been working in spirea and so we have a good ploidy series in spirea, mostly focusing in spirea japonica and further specializing in the variety alpina, which are really quite dwarf.

Ryan Contreras:

You know everything is going smaller, lots are getting smaller Folks are interested in more compact and smaller plants, and it also has benefits the nurseries because it requires fewer touches, less pruning and just less care in general when you have a more compact plant. We've been working you know a number of folks Mark Brand at Connecticut, tom Ranney at NC State been working on barberry. But we've been working on barberry and we've got some seedless barberry coming as well. But by far the most effort that we've put in to oh and I should mention Prunus loricerasis. It's still a really important species. It's still a really important species.

Ryan Contreras:

And so we've actually been trying to do interploidy, interspecific crosses with Prunus loris erasus and Prunus lucitanica. That's a, from cytogenetically speaking, it's the most interesting group ever. Prunus loris erasus is a naturally occurring 22 ploid. Prunus lucitanica is an 8X and so we've been manipulating ploidy in both directions and we now have haploids that were developed from Prunus loriseracus and we've got induced polyploids from Lusitanica. So I feel confident we're going to get there. But regardless of those, we've still put more effort into maples than any other and we've got a triploid Norway maple and a triploid Acer gennala or emmer maple that are both in tissue culture We've been testing and hope to release in the near future.

Sam Humphrey:

You've got a lot going on. That is so many different projects and collaborations. We're curious what is next for you? What are you excited about right now?

Ryan Contreras:

I am most excited about a system. We just installed, a drought stress phenotyping system called a plant array. So my current PhD student, keen Maher, is working on evaluating standard cytotypes with our induced polyploids, and so this system allows us to very precisely impose specific levels of drought stress. And because I've long wanted to get into this realm of drought stress phenotyping but it's really hard People spend their entire career doing nothing. But you know the physiology of drought stress and trying to, you know, accurately impose and evaluate plants under drought stress. Well, this is a game changer. It's a, it's a, you know, computer-based module that you tell it I want to put it at you know 0.15 or 15% volumetric water capacity or whatever it is, and it and it does it. And then where it it, it, it also, uh, gives you the physiological response in terms of biomass accumulation, water use efficiency, transpiration, stomatoconductance, all of the you know, all of the physiological responses. So that's been a real game changer. And our we're we're collaborating with Kelly Vining, who is a bioinformatician and genomicist, here at Oregon state, uh, to look at gene expression associated with this, because we've been developing these polyploids with the primary goal is seedlessness, so they don't escape cultivation and we can reintroduce Norway maple into Massachusetts and New York right, because that's an important market for our growers. York right, because that's an important market for our growers.

Ryan Contreras:

But now there's some good scientific evidence out there that as we increase or induce polyploids, we're also improving the resilience to drought stress.

Ryan Contreras:

You know, and I long ago, the phrase stuck with me, you know it's like in the future, water is going to be the new oil.

Ryan Contreras:

We're going to fight wars over water in the future, and so I hope we're not fighting wars over, but nevertheless the climate change is going to exacerbate drought stress. We've got longer, more severe drought stress, and so that's what excites me right now A, the ability to actually do the phenotyping work and then the collaboration and the reduction in costs of some of these tools where we can potentially identify genes that we can then use in future breeding. So I think that's really exciting and I'd be remiss if I didn't mention that we're you know it is very buzzwordy and you know it's the hot new thing, but we are collaborating with some folks who are doing imaging and machine learning, trying to use artificial intelligence as a preliminary screening tool If we can identify some imaging cues where we can image large populations of plants that may be more drought resilient and then do sort of a deep phenotyping using the plant array. That's where we're hoping to go. So we have a collaborative team put together and hoping to go down that realm.

Sam Humphrey:

There's a lot to be hopeful for.

Curt Rom:

You know, ryan, it seems like you're very excited about what you do. I got one more quick question then we need to kind of wrap up a little bit. What do you like most about your job as being a university professor at a public land grant university? What gets you to the office every morning?

Ryan Contreras:

a great question, kurt, and there's a lot, there's a lot. I have the best job in the world and I think it's a combination of I don't do the same thing two days in a row. I love that and I love I've got blisters on my hands right now from running the chainsaw. On Tuesday, I got to go up and represent the department at the Caneberry Field Day yesterday. I get to talk to you great folks this morning and I'm going to go to the greenhouse and watch my student set up this plant array and test it out. And so I get to work with other excited scientists, both aspiring scientists that I get to help train, as well as learning from people who've been doing it four times as long as me, doing it four times as long as me. So I love the diversity, the excitement. I love the plants.

Curt Rom:

I love learning.

Ryan Contreras:

I just love every bit of it. I slipped and fell into the best career. That fits me better than anything I can imagine.

Curt Rom:

Yeah, I agree with you, it's a good gig.

Ryan Contreras:

Yeah, it's better than digging ditches, but you know, some days that's fun too.

Sam Humphrey:

Ryan, thank you so much for this. After this interview, I'm going to go out and I'm going to become an ornamental plant scientist. Just like you, I'm so excited about the future. Thank you so much for this.

Ryan Contreras:

Well, thank you for the opportunity to chat with you today.

Curt Rom:

Yeah, it was a really good conversation, I think, very enlightening. Well, we covered a lot, but thanks for sharing all of this with us and thank you, curt. Well, sam, that was a really interesting interview with Dr Contreras. I felt like I learned a lot. You know again, as I said in the interview, you know invasive plants. It's kind of one of those unintended consequences of something that was intentional to introduce new plants, of something that was intentional to introduce new plants, and it also became clear to me that not all invasive plants are invasive in all situations and all environments. And then you know, climate change might have an impact on that.

Sam Humphrey:

Oh, absolutely. And it's fascinating too, because there are even within certain states like I am from Florida and I did a little bit of invasive plant research in undergrad and even within this relatively small area of Florida, these different governing bodies have different lists of the worst invasive plants in the state. Some organizations might have a little bit of a broader definition of what counts as invasive, and so there are all these traits and all this diversity, and scientists are just grappling with trying to keep up. So it's it's really amazing to hear Dr Contreras talk about how he's using so much technology in his work.

Curt Rom:

Yeah, you know, I think that it's really interesting that they're using both kind of maybe 30 and 40 year old mutagenesis techniques, but they're also using some real cutting edge molecular biology, crispr techniques and it's clear that scientists working on these plant systems now and breeding and developing these plants, they have a much better understanding of it and they're trying to avoid the unintended consequence. So very interesting interview we had. Absolutely, I think this episode helped me understand the value of ornamental plants and the development of new cultivars, but also enlightened me on the problems of invasiveness, and it's clear that scientists are now aware of it and they're using these various techniques and a lot of these new techniques to prevent invasive plants as they introduce new cultivars and new plants into our landscapes.

Sam Humphrey:

To read more about this topic, check out Dr Contreras' paper Genetic Methods for Mitigating Invasiveness of Woody Ornamental Plants Research Needs and Opportunities, which is published in Hort Science, one of the open source peer-reviewed journals published by the American Society for Horticultural Science. You can also reach out to Dr Contreras to ask him more questions at ryancontreras at oregonstateedu.

Curt Rom:

If this interview resonates with you, I recommend renewing your membership or joining the American Society for Horticultural Science so you can be part of interest groups like the ornamental plant breeding, the ornamental landscape and turf or the propagation interest groups. If you'd like more information on the American Society of Horticultural Science in general, go to our website. Ashsorg Sam, thanks for the conversation today. I enjoyed visiting with you. It's always a pleasure.

Sam Humphrey:

It's amazing to see you, Kurt.

Curt Rom:

Have a great week until we meet again. The ASHS podcast Plants, people and Science is made possible by member dues and volunteerism. Please go to ashsorg to learn more. If you're not already a member of the ASHS, we invite you to join. Ashs is a not-for-profit and your donations are tax-deductible.

Sam Humphrey:

This episode was hosted by Samson Humphrey and Kurt Rohn. Special thanks to our audio engineer, andrew Sheldorf, our research specialists Lena Wilson and Andrew Sheldorf, our ASHS support team, sarah Powell and Sally Murphy, and our musician, john Clark. Thanks for listening.