Participatory Plant Breeding For Better Tasting Organic Tomatoes - An Interview with Dr. Ambar Carvallo Lopez

Most of us think new crop horticulture cultivars are invented behind closed doors, then handed to farmers as a finished product. We wanted to explore that assumption, so we sat down with Dr. Ambar Carvallo Lopez, currently a Post Doctoral Research Associate at the University of British Columbia and an ASHS award-winning author and plant breeder whose work shows how research progresses when growers and consumers Participate in the science. If you care about better-tasting tomatoes, resilient organic agriculture, and the future of local food systems, this conversation connects the dots from seed to plate. 

In this episode we walk through the concept of participatory plant breeding, where farmers are involved early to define breeding objectives and then help shape selection by trialing lines on their farms. This is a unique form of citizen-science.  

Ambar shares how the University of Wisconsin-Madison, Where she completed her PhD, tomato breeding program uses iterative seed exchange and real-world feedback to shorten the “will this work on my farm?” gap that often slows adoption. Along the way, we talk about genotype by environment interactions, high tunnel production, and why building trust with stakeholders can be as important as collecting data. 

Ambar explains why tomato flavor may have declined over time as breeding programs prioritized yield, disease resistance, and plant structure, and how accessing heirloom tomato diversity can help recover the genes and volatile compounds tied to better aroma and taste. In the conversation also digs into practical breeding targets for organic systems, including foliar diseases like Septoria leaf spot and early blight, plus the behind-the-scenes reality of deciding when a line is ready to release and how to handle credit and IP when farmers are true co-creators. 

If you finish this episode thinking differently about what’s behind a great tomato, share it with a friend, subscribe for more horticultural science, and leave a review so more listeners can find the show.

Read "Improved Tomato Breeding Lines Adapted to Organic Farming Systems Have Enhanced Flavor, Yield, and Disease Resistance", winner of the 2025 ASHS Outstanding Vegetable Publication Award. https://doi.org/10.21273/HORTSCI17799-24

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.

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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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Transcript

Welcome And Episode Focus

Curt Rom 0:11

Welcome to Plants, People, Science, a podcast by the American Society for Horticulture Science, where we like to talk about all things horticulture.

Sam Humphrey 0:22

I'm Samson Humphrey, I'm a PhD student researcher at the University of Tennessee, and I'm one of your co-hosts.

Curt Rom 0:28

I am your other co-host, Curt Rom, a university professor from the University of Arkansas. We want to welcome our audience today. Thank you for taking the time to join us in this conversation. You know, Samson, I'm looking forward to today's conversation. And one part of my past research life was being a fruit breeder. And I always think it's fascinating to talk to breeders about their approach, the kind of things that help them form their breeding objectives and the directions they take.

Sam Humphrey 1:03

Oh, absolutely. And the fact that it is such a team sport, it's such a team effort, and the way that people go about these collaborations seems to be entirely just varied. I really love seeing these varied experiences from breeders across different crops across horticulture.

Curt Rom 1:20

And you know, this particular episode today was kind of based on really an award-winning publication in our one of our ASHS journals. Uh, sort of caught the eye of the peers in our society as well. I think it's fascinating as we'll find to explore the idea of how we in the academic world, which we're often accused of being in the ivory tower and being isolated from culture, society, and our stakeholders, uh, today our episode will really talk about how stakeholders are engaged in the process of developing horticultural plants.

Sam Humphrey 2:04

Absolutely. And then it's called participatory plant breeding, and that's what our focus is on today. Our guest is Dr. Ambar Carval Lopez, and we invited her, like you said, Kurt, because her paper won the ASHS Vegetable Publication Award. Her work was on breeding tomatoes in a participatory plant breeding program. On this podcast, we've never actually had a discussion about what participatory plant breeding is, so we jumped at the chance to have her on. Let's take a listen.

Curt Rom 2:57

Today we're happy to be joined by Amber Carvallo Lopez. Um so uh Dr. Carvallo Lopez, tell us a little bit about you. Where are where are you at now? And uh before we get going, can I ask you a question? Um we want this to be a good conversation, and how do you prefer to be called? I mean, I know you you're a kind of a recent uh PhD. Do you prefer to be called doctor or would you like us to call you Amber for the conversation?

Ambar Carvallo Lopez 3:24

Um hi, Curt. Um, first of all, it's a pleasure to be part of the podcast. Ambar is just fine.

Curt Rom 3:30

Okay, we'll we'll do that. So take give us a little bit about your background. Where are you at now and how did you get to where where you're at? Introduce yourself for us.

Ambar Carvallo Lopez 3:39

Yeah, for sure. So I right now I'm a postdoc at the University of British Columbia and I'm doing research on carrot genomics, involving both kind of like participatory plant breeding, working with farmers, as well as looking more into the genetics of heat tolerance and drought tolerance for improving crops for the you know changing climates and increasing temperatures around the world, specifically in Canada.

Curt Rom 4:06

Well, that's a big that's a big challenge because definitely the climate's changing, and you know, we need to have a more diverse nutritious food supply.

Ambar Carvallo Lopez 4:15

Yes, definitely, definitely. And then it it like my studies and my career kind of like natural led me to this. I did my PhD in the University of Wisconsin Madison, where I was working in a different crop but similar approaches. I was working with tomato breeding for organic systems, also involving participatory breeding, and we can talk more about that in a few minutes, um, and as well as looking at fruit quality, because you know, people are not too happy about the flavor of tomatoes right now. So we're trying to see how we can improve the quality of the fruit following, you know, using genomic tools, trying to find the genes controlling for fruit quality, um, and focusing on the needs of organic and local systems.

Sam Humphrey 5:02

Yeah, really important stuff. I I was so excited. That's actually that's why we're talking with you today, is because you won the publication award for that manuscript, for this tomato manuscript about participatory plant breeding.

Ambar Carvallo Lopez 5:18

Right, yeah, yeah. And I was so surprised first. I didn't know that such an award existed. So it was a really happy surprise to receive that. Unfortunately, I wasn't able to go to the conference to receive it, but um it was it was nice to see this kind of work, especially because we were focusing on the participatory approach and how we've worked closely with farmers to improve this tomato lines, um, to have that highlighted in the scientific community because sometimes that can be left aside a little bit.

Sam Humphrey 5:48

Yeah, it's a fantastic paper. I'm really excited to talk about your tomato work. But before we get there, how did you start? How did you come in to and and become this scientist you are today?

A Winding Path Into Breeding

Ambar Carvallo Lopez 6:00

Yeah, that's a that's always a fun question to answer because it wasn't too much of a straight line. I got into agriculture pretty randomly, I want to say. I I knew I liked the outdoors, I liked plants, and when deciding for a career in undergrad, agriculture seemed like it could be a good fit, although I'm not coming from a farming background at all. Um, and throughout those those years of learning about agriculture, agronomy, and horticulture, I realized that that was what was I was passionate about. And then I got an opportunity to do a five-week internship or apprenticeship in the Netherlands, um, like in my third year in undergrad, to work in lilies breeding, so flower breeding. And by working closely with the breeder there who was so passionate about his work, that really opened up that the whole world of seed production, seed improvement, and what that means for agriculture in general. So that's how I started. And you know, those things that happened very, you know, randomly, this opportunity came out of nowhere to this specific program, um, a university, and then they chose five students. Not really uh a very clear way of choosing those students, and anyways, so that's that's how I I got interested in plant breeding. And after finishing my undergrad, I kind of like wanted to experience different areas of agriculture, so fruit production, vine production, and vegetable production. I worked for a year in ornamental propagation in California, and that kind of like settled what I liked and what I didn't like in terms of me joining an industry. And I was very lucky to find a master's program that kind of included both of the things that I was starting to get passionate about, which was sustainable farming and plant breeding. And then I I got in contact with Julie Dawson at the University of Wisconsin-Madison, and she was working on tomato breeding for organic farming systems, among other projects, of course. So yeah, things worked out, you know, really well. And then I got the possibility to keep exploring that path.

Sam Humphrey 8:27

It's really cool too. You you said you wanted more experience with different crops, fruits and vegetables and and different things. And here you are. Like you you did your PhD with fruits and with tomatoes, and now you're doing vegetables, you're doing carrots and maybe other things and roots, crops, and um, yeah, it's so exciting to see that you haven't necessarily like nailed yourself down and that you're still exploring.

Ambar Carvallo Lopez 8:53

Yes, definitely. I I think that's it's always good to keep an open mind because when you're doing your master's or PhD, you have to go very deep into one crop, right? And one trait or something very specific. And it's it's not always the case that you're gonna continue working with the same crop. Um, so for me, it was very exciting to find this the current project that I'm working with. Um, it's a new crop, it's a biennial crop, which the seed production system is completely different. We could have to do cheap seasons. Um, so a lot of learning um through this process.

Curt Rom 9:28

So, what attracted you to the University of Wisconsin? Was it Dr. Dawson's program? And uh the were you interested in the project that she had, or were you interested in the crop, or was it Wisconsin? How did you get that match? So, was it really that you wanted to work with Dr. Dawson?

Ambar Carvallo Lopez 9:45

It was it was a mix uh of things. First, the University of Wisconsin-Madison is very renowned for their agricultural program and their plant breeding program specifically. So that's something that I was eyeing from from the beginning, and then I started to search who I could work with, uh, who could be a good match. And there were, of course, mm multiple professors that I thought they were doing interesting things. Um, and so Wisconsin was a new place for me. Of course, I hadn't been there before. I had to look up the weather, very harsh winters, me coming from Chile from a Mediterranean climate was definitely going to be a challenge, but I was I was excited about it to leave something experience, something different, excuse me. Um I also saw there were multiple lakes in the area, so you know, trying to see the positive sides of of the region. And then, of course, learning about the work of um Julie really you know settled my decision of applying there.

Curt Rom 10:49

Well, I think Wisconsin's a great school, but I say that with a lot of bias because my father got his PhD in the Department of Horticulture.

Ambar Carvallo Lopez 10:57

Oh, that's wonderful.

Inside The UW Tomato Program

Curt Rom 10:59

At the University of Wisconsin, and my brother got a PhD from the University of Wisconsin. And they do have a long standing tradition, you know, 75 uh plus years in vegetable breeding, you know, for a long time. And a lot of the innovations in our vegetable system uh really occurred there. And then even some of our fundamental knowledge with quick plants, you know, really. So that was that's a great place for you to land. Yeah, and so tell us about your theme, your dissertation project. That's what we really want to dig into.

Ambar Carvallo Lopez 11:34

So okay.

Curt Rom 11:36

What were were you kind of assigned that, or was this something that was in the general work that Dr. Dawson was uh her her field, and you really wanted to dig into a project? Go go through the set it up for us. How did it go?

Ambar Carvallo Lopez 11:49

Yeah, yeah, yeah, for sure. I I think it's something that we kind of built together. The tomato breeding program was already happening, which was mainly the participatory breeding. So when I got there, just to paint the picture, they had already started with uh with a breeding program, which means that they had selected some perennial lines based on what the farmers were saying they were interested in, uh what they needed in terms of disease resistance, fruit quality. And then they already had made some crosses and had at least three generations in, in which they were sending seed back to farmers. Farmers were evaluating the different lines in their farms, making their own selections, and then sending seed back to us at the program, and then asked kind of like continuing that iterative process. So I got there when it had been already like two or three years of this to continue the work and kind of like finalize those lines, continue the selection process, kind of like the pipeline. And so that was the master's my my master's thesis. And then when we were talking with uh my advisor there, we we really wanted to get deeper into what how can we improve fruit quality if you know the the genetic variations may be very limited. Do we want to, you know, maybe use heirlooms? How do we set this up? And so that's how we kind of like proposed the second like big chapter, or third, I can't remember which which one it was, but um, so this one we were trying to do more like a genetic analysis, and this is this the manuscript that I'm working on right now that I'm trying to finish um on carrying out you know a dialogue system, I mean mating design between heirlooms and some modern lines, and see if we can bring back some of that genetic diversity that might bring as well flavor and other fan tomato characteristics. So that's like the two parts of my PhD, and then I also did a lot of work on disease resistance. So there's two diseases in Wisconsin that are affect tomatoes. Well, one of the mains, I mean, which are Septuari leaf spot and early blight. And they're both fungal, they're both foliar diseases that when they get in the field, they're really hard to control, especially for organic farmers, because there's not that many tools or products that you can use. So it's more on the prevention. Um, so we partnered up with a local seed company and uh the university of Cornell University, where they had done all the pre-breeding work to find genes and potential gene genetic markers associated with septoria resistance. So that was a whole other you know, area of my project in which I was able to look at tomatoes from different perspectives for for adaptation, for quality improvement, as well as disease resistance.

Sam Humphrey 14:57

That sounds like the ideal PhD project. You gotta look at all those different things.

Ambar Carvallo Lopez 15:03

Yeah, yeah. I was very lucky that that I had the flexibility, I was given the flexibility to do that, and the support uh of my team, of course, because all of this involves multiple field trials, multiple locations. We had a field trial at the seed company, so like building strong relationships with them was very important as well.

Conventional Versus Participatory Breeding

Sam Humphrey 15:23

That is so cool. So let's take a backup here because you mentioned organic producers. And then also one of the features of your paper was about participatory plant breeding. So could you tell us a little bit about conventional breeding and how that differs from participatory plant breeding?

Ambar Carvallo Lopez 15:43

Yes, definitely. So I think just to put this into perspective, conventional breeding is the way that we, or breeding in general, is the way we are trying to improve crops for for humans to you know get more yields or get benefited by growing certain crops. And so throughout the years, we've been selecting for different traits like yield or disease resistance, and every time that we make that selection, we leave, we we potentially lose other traits. And and so that's the general very summarized way of talking about plant breeding. And then conventional plant breeding is a very centralized process, right? There's either a seed company or sometimes either public efforts in a university or other institutions. A lot of those decisions are made within a very small group of people, they're working on specific traits, um, generally working for conventional agriculture, which means there's a lot of you know relying on fertilizer, like high-input use, fertilizers, pesticides, very uniform, you know, growing systems. And so this kind of like varieties are that are developed and then released. Sometimes they perform really well in conventional settings, but when you go into less you know input farming systems, either organic or just because people don't have access to these products, um, the varieties don't really perform that well because they have been bred under these you know high input conditions. So participatory plant breeding started in developing countries because of this specific issue. Because they couldn't, farmers couldn't rely on this conventionally bred seed, it was expensive, and so they started doing their own selections on farm um and kind of like collaborating with each other. And so there are many different levels on how participatory plant breeding can be you know carried out, and because it started in developing countries and in the systems that were low input use, it kind of like made sense for organic agriculture to kind of like mimic or or learn from this approach because organic systems are very varied, very diverse, usually low-input use. I'm not saying there's no fertilization because there's compost use, of course, there's organic pesticides, but it's more reduced as well. And and of course, organic farmers or local farmers that sell in the farmers markets, they're looking at different traits that conventional big ag. And so there's a there's a need for there's a different need for those markets. And so for organic farming, it's been something that has been developing in the in in the last few years in different crops, mostly vegetables and grains. There's been long-standing grain participatory plant breeding programs. Um and basically now what it looks like, it can be, you know, the farmer can be part of the decision making from the beginning on deciding what are the traits that are gonna be improved, uh, who's gonna make gonna be making the crosses, who's gonna be making the selection and the evaluation. Um so that's kind of like an overview of participatory plant breeding. And I do want to say that that's there's a lot of information out there, and there's so many different ways of doing it. Uh, but kind of like the approach that we used at the University of Wisconsin-Madison was getting the consumer, which includes the the farmer, the chefs, the the actual people eating the crops, to talk about what do we want to see in tomatoes, what is missing. And so that's how the objectives were set from the beginning. And that sets up the whole rest of the of the process.

Setting Goals With Stakeholders

Curt Rom 19:49

Yeah, I'm very interested in that. Of course, uh, this participatory plant breeding, as you're you're talking about it, I mean, it's a tremendous way from a breeding uh uh standpoint to better understand the genotype by environment interactions. So that's that that's wonderful. But back to your point. Uh, how did you set the breeding objectives? You know, who did you listen to? How did, you know, very often as a former plant breeder, you know, uh we kind of formulate those breeding objectives very individually, but this is a different approach. So who did you listen to? How did you incorporate that? And how did you value the different input you got, whether it be from a grower, uh seed company, or the consumer, or I mean your breeding team?

Ambar Carvallo Lopez 20:39

Yeah, this is this is such a relevant question because it also indicates how other institutions could mimic. So, how do you define those objectives? And for for the program at the University of Wisconsin-Madison, as I mentioned, I got there when this had already started, but I can tell you know how it happened before I got there. And basically, participating in relevant organic farming um conferences or roundtables, uh, there were a couple of surveys sent out uh to understand the needs, the the trait needs of conventional organic farmers just to see what are the differences, are people thinking about the same things? Um, and that's how it got set up. And of course, throughout the process, having check-ins with the farmers. And because they were also doing their selection in their farms, we could make sure that whatever that we're selecting, it's also including their preference. And just to like tie it to what I'm doing right now, we're also carrying out a participatory, you know, plant breeding project in carrots. And it's quite similar in the sense that you know, we saw the need that a lot of if producing carrot seed in Canada is very hard. And so sourcing uh locally produced seed is not really a possibility. So it relies a lot on international market. In in other, you know, produce producing systems. And so that need was definitely there. And also the availability of open pollinated varieties that could perform really well. Because a lot of people use the F1s. Then I'm not, I'm not, I want to be clear that I'm not saying that F1s are a bad thing, but some farmers would rather rely on open pollinated because if the F1 producing company decides to not produce it anymore, they don't have any other options that they, you know, that they trust. So basically, we wanted to produce an open pollinated carrot variety that could work well in Canadian systems. And to do that, you know, different parental lines were chosen. We carried out the crosses, we send out seed to the farmers, and then they grow the roots, and then they send back the roots to us. We do the seed production in greenhouse, then we bulk that seed, and then continue an iterative process. So and again, we're always taken in with the with the farmers that are growing the carrots, or in the other case, the tomatoes.

Curt Rom 23:11

Yeah, with the tomatoes, you know, I would just think I just I'm really struck by this. I think it's an interesting and fascinating way to construct your breeding objectives because a grower is going to tell me, yeah, yield is important to me, disease resistance is real important for the organic, so I can reduce my inputs. I'm growing them inside of a controlled environment of a high tunnel, which is modified environments. I've got to have something that can take that different kind of light quality and maybe different kinds of temperature regimes. And then the consumers are saying, I want a nice, red, round, really flavorful tomato. And you know, we hear consumers talking very frequently that tomatoes are the bellwether of all fruits and vegetables. Those breeders have bred the flavor out of it. And here you are, you know, talking to consumers and understanding that that that's uh that's important. I could also see with organic growers, because the organic promises to deliver a high quality, nutrient-dense, consumer acceptable product. So uh how how did you, you know, you you had really dug into this flavor component.

When A Line Is Ready

Ambar Carvallo Lopez 24:26

Yeah, and that was uh that was a definitely a new world for me. I hadn't studied what flavor entails and how we perceive it. And I I got really into it to understand how that there's the question, why did we lose so much flavor in tomato? It's true, even even I, that I'm not that old, sometimes say the tomatoes that I ate when I was younger were tastier. So I can imagine that people that ate tomatoes 20 or 30 years ago could also taste the difference. And so there's been a lot of work done on this. Um there's a group, uh T-Men et al. that they published a paper talking about the genetic roadmap to flavor improvement. And basically they found that through domestication, where we were selecting for certain traits like yield and resist resistance, as well as plant structure, which is so important in tomatoes because we have to trellis them, we started to lose some of those genes that were positively correlated with flavor and accumulate certain genes that were you know producing volatile compounds that are not you know so good when we taste the tomato. So basically getting worst flavor by both ways, losing the good genes and also accumulating the bad ones in in small proportions, of course, because flavor is such a complex attribute. There's so many volatile compounds included in this, and as well as how we perceive it in terms of the texture. Um, but that was very interesting to see. So there is a genetic real uh challenge there, so to how much improvement we can make. And I think this is where it's key to go to germplasm that maybe has been left aside for a bit, those heirloom lines that could look a little bit more wild, maybe not so productive, a little bit more of like cracking issues, but it can maybe harbor more of that genetic variance specifically for fruit quality. And that's what we were trying to do in the with the manuscript that I'm working on right now.

Sam Humphrey 26:31

That's amazing. So you're going through this process, you're sending uh plant samples or seeds back to the farmers. Seeds, yeah. Uh, and they're growing out a new crop and they're sending you back. How do you determine what should be released? How do you know when you're done with this like iterative long-term process?

Ambar Carvallo Lopez 26:52

Yeah, that's the other classic breeder question. Is this done? Are we ready? Um, and I think there's a you know, in tomato, we because it doesn't have inbreeding depression, it's nice, you can keep in you know self-pollinating it to reach something that is very uniform. So that's the fun thing with tomato, uh, as well as how easy it is to make crosses. Um, so usually when you reach the seventh generation, you start to see really good uniformity, and you just have to start to discard things that are clearly off-type. And this is where you have to carry out larger trials. So you reduce the number of lines that you evaluate, but you increase the number of plants per line so you can truly see how uniform it is, how stable it is. Hopefully, you're growing this in multiple environments to see some genetic by environment um interactions until you reach to a point that okay, if you're getting good feedback from the farmers, you're getting your data with the decent yield. Um again, we were not trying to come out with the best performing tomato that everyone can grow and it's gonna be um the best producing, but something that farmers felt like, okay, this was bred here, this was bred with my input. I know that's where this is coming from. So actually, we're in the process, or I say me, myself, and and the team at UW Madison of working with the university because, of course, there's some IP-related, you know, processes that have to go through in terms of, you know, because the research was done at the university with university resources, navigating those things because because it is a participatory approach, the farmers are also authors and creators of this material. So we want to make sure that we can credit them. Um, so yeah, that process is it's on the works, but yeah, there's two lines that we're really excited about, that we got really good feedback, um, and I'm really hoping to see it out there available for farmers and gardeners to grow.

Sam Humphrey 28:58

That must be so rewarding after such a long process and it having even started before you arrived there for your PhD. Oh my goodness. So, did you ever get to go visit any of these farms and see the plants in the field out there?

Ambar Carvallo Lopez 29:14

Yeah, yeah. I the farmers that participated were pretty spread out in the Midwest, so some in Wisconsin, some in Minnesota, mostly farther. Uh, but we did have a farmer join us like in the last two years of the evaluation. So I was saying, and he grew a lot of plants. He was very excited, he loved the research. He also works at the university, so that's how he had such a close relationship. Um, and so I it was exciting to see you know the plants being grown in a different environment other than the research station. Even though we try to mimic what farmers do in their farms, we don't, you know, we don't try to not spend too much time because farmers have very limited time uh to spend on each crop. Um so yeah, I was able to do that and and and see that they were quite uniform and they were performing similar to what we were seeing at the research station. So that was good.

Sam Humphrey 30:09

I'm curious how your research plots are different from what you see on a typical farm or maybe that specific farm that you visited.

Ambar Carvallo Lopez 30:19

Mm-hmm. Yeah, so usually at our high tunnel or even in the open field, we have multiple replicated plots. Um in a farm, usually they're growing a few varieties, or if they're very diversified, they're they'll be growing many different varieties depending on their their market. Um, but we we were really trying to mimic the conditions in terms of the trellising and how you're managing opening and closing the high tunnel, using straw as a mulch. So I would say it didn't differ so much, or I would like to think it didn't differ so much uh in terms of the watering, following the watering strategies as farmers were doing. So sometimes they'd say, Oh, we water twice a week, uh, we let it dry down a little bit. And so we my first couple of years, I kind of like learned to do that, and then it comes, it came more naturally the following years.

Sam Humphrey 31:15

Yeah, because this is like a more local effort, right? More more local for for breeding for these organic growers.

Ambar Carvallo Lopez 31:23

Definitely.

Curt Rom 31:26

I want to go back and ask you, Voucher, by the way, congratulations on the award-winning publication, the outstanding publication in ASHS journals related to vegetable crops. And for our listeners, I'm sitting here holding a copy of it, improved tomato breeding lines adapted to organic farming systems, have enhanced flavor, yield, and disease resistance. I mean, that is a conclusion in the title, but what were some of the other takeaways that you you have for us? What else? Those of those that are not going to read it and just gonna listen to us today, uh are there some big takeaway messages, some things that you really learned that you're really uh uh pleased about and maybe excited about?

Ambar Carvallo Lopez 32:09

I think one big takeaway um is that the approach works. You know, it it does take a lot of effort. People ask, like, well, is this financially you know uh possible? Does it make sense in terms of their time? It is time-intensive in in how long it takes, but compared to a regular conventional breeding program, they also take time. So that's not such a huge difference. And I think in terms of one big difference is that because we worked closely with farmers from the beginning and they were already trialing the varieties almost when they're finished, the adaptation, the adaptation process of where the farmer decides to include this variety in their rotation or their you know season is much shorter because a regular seed company goes through all this breeding process and reaches a somewhat finished line, and then they have to go through the marketing process of trialing these lines and convincing farmers to grow them, and so building that close partnership, that trust is really important. So that's something besides you know the other results that we got in terms of the yield and the disease resistance and and the fruit quality, I think that's another key takeaway that like people to you know to take with them.

Sam Humphrey 33:35

Absolutely. But it must be so difficult to keep up all of these relationships with these different farmers and to keep in contact with all of them. Did you have to and is that part of your role, all of that outreach, all of that communication?

Ambar Carvallo Lopez 33:51

It definitely is a challenge. I was very lucky that the the program at the University of Wisconsin-Madison, they already had built a really good way of keeping relationships with farmers. I did when I started my program in 2019, my master's, you know, the COVID pandemic came, and so it was hard to you know maintain those relationships for sure. So we had a little hiatus there on how you know how many visits we would do to farmers, but definitely maintaining email connection and sometimes phone calls. Um, I think that's something that that has to have like a plan or like a process set up to make sure that you continue to build those relationships. Um and you can't expect farmers to like be answering you all the time and really sending you feedback throughout the season because they're very busy. So they're in being very mindful of okay, maybe I'll reach out once or twice and we'll see and take it from there.

Curt Rom 34:57

Okay, I'm gonna ask you a very non-scientific question. Okay, the question I'm sure you've been asked before. So you're you were breeding tomatoes for good flavor. What in your mind as a scientist or as a consumer, what is a really good tomato? What should it really taste like? What should it's texture and its flavor? So you know, should they be sweet, should they be tart, should they be sour, you know what's a good tomato for those of us that maybe don't know?

Ambar Carvallo Lopez 35:30

I haven't tried the perfect tomato.

Curt Rom 35:34

We're in a lifelong search of that perfect tomato.

Ambar Carvallo Lopez 35:38

I a really good balance between sweetness and acidity. It's it's key, of course. But then also while you know getting involved in this project, I tried so many different tomatoes. Um, and then umami became a thing that I was looking for, so that more like umami describes like the soy sauce flavor, uh, something like that. And it's hard to put it into words without tasting it. Uh, but when I discovered that, I was like, oh, that's a flavor that I really like, or like the smokiness that sometimes some varieties might have. Um really something that's more complex than just sweet tomato, for me at least. And this is definitely a question that varies, you'll get a very different response on the country you're at, the culture, um, and the texture as well. It varies if it's for fresh consumption, if it's for soup or tomato paste. So I'm right now I'm talking about the fresh tomato. If I buy it at the farmer's market, I want something juicy, uh, with a good flavor complexity, and in texture, I guess something not too soft, but also not too crunchy, if that makes sense.

Curt Rom 36:52

That makes a lot of sense. And I I think it's remarkable, uh, even in that program where you were breeding tomatoes for northern conditions, and you know, we don't normally think about Wisconsin, Minnesota, the Dakotas as being tomato states, but growing them in high tunnels. Now you are actually creating a product that probably is with enhanced flavor, but also is probably being delivered more to local and regional markets, being delivered fresher as well, or and more mature. So that's a really notable thing in your project. Uh I really appreciate that from the breeding efforts at Wisconsin.

Ambar Carvallo Lopez 37:30

Yeah, thank you. And it's something that attracted me too as well from the program because uh the program itself is called Regional Local and Regional Food Systems. So it's it basically choose how do we support our local systems, and that's through breeding. There's a strong extension aspect to it as well, on evaluating different management practices. Another grad student was evaluating what's the actual difference between growing tomatoes in the open field, a caterpillar tunnel, which is a low financial commitment with the benefits of a you know covered structure and the high tunnel. And what are the, you know, how expensive is it? What's the labor involved? And so all of that really complemented the work that I was doing specifically in the breeding. So what what do you say is something that actually attracted me to join the group?

Sam Humphrey 38:23

Yeah, that like research infrastructure around you, people studying different things that complement what you're doing.

Ambar Carvallo Lopez 38:29

Definitely.

Food Systems And Community Lessons

Sam Humphrey 38:30

Wow, that's incredible. So I am hearing a lot of like tones of community in this. There's the research community around you that's like feeding into your breeding work. There's the community and different communities at conferences and these grower events where you're talking to the people who are actually growing the tomatoes. There's community that's local around you. Um, what would you like our listeners to remember about your work or the things you've learned on this very, very interesting path?

Ambar Carvallo Lopez 39:06

Yeah, I think being curious about where your food comes from, I think that's something that I always kind of like stop and ask myself when I'm going to a grocery store or going to a farmer's market. Um, the fruit that and vegetables that we see out there, it's not just producing them. It's there's so much work behind people making decisions on what do we want to break for, where is this variety going to work well? Um, yeah, are we focusing on flavor, disease resistance, what what management practices are the farmers using? So there's so much work behind every crop that we grow and that we eat. And so, yes, in community, it's such a big aspect of this because none of this is done by a single person or even a single institution. You know, there's so many connecting points on getting the food from the field to your table. And I think I I I personally like to stop and think about that as often as I can. I'm not thinking about it every single day, but I like to bring it up because it makes us value as well more what we're eating and you know, the work that farmers do as well.

Curt Rom 40:19

Amber, you've made me you know reminded me that when I go to the grocery store, I need to think about that the entire part of our food system, where that food, you know, how it was delivered to the store where I buy it or the or the farmer's market, uh, the farmer who grew it and the growing conditions in which they grew it. But even back behind that, there are people like you. There are those scientists, uh those breeders that are working to create a better product for the farmer as well as a better product for the consumer. Well, Amber, you had a tremendous story. This was really interesting, and uh I I learned a lot of about both uh participatory breeding and is and in your particular program. Really appreciate you coming today and sharing your story with us.

Ambar Carvallo Lopez 41:10

Well, thank you so much. I really appreciate the invitation, and I'm always happy to talk about tomatoes and now carrots as well. Uh that maybe can be in another at another time.

Curt Rom 41:20

Well, I'll be looking for some British Columbian Canadian uh carrots.

Ambar Carvallo Lopez 41:24

Yeah. We'll try to get there.

Curt Rom 41:27

Well, thank you very much for joining us. And Samson, always great to have a conversation with you. I thought today was a lot of fun.

Sam Humphrey 41:34

So did I, Curt. Thank you so much, Ambar, for coming up.

Ambar Carvallo Lopez 41:38

Thank you, everyone. Take care.

Sam Humphrey 41:52

Wow, that was a fantastic interview. Oh my goodness. I before this, before reading this paper and talking with Ambar, I was not aware of what participatory plant breeding was. This was so cool.

Curt Rom 42:05

Again, getting that involvement from growers and farmers, uh, not only on the front end where they're making creating the breeding objectives, so you're really breeding to make a difference, but getting them involved in the evaluations uh and so they can give you some some real-world feedback. I mean, it it's kind of uh it was uh Amber's dissertation. I mean, it was really good science, but there was a little bit of aspect of a citizen science kind of involved in that. And I think that's really valuable. Also, I was really interested in, you know, and it was a great lesson to remind me that a dissertation can make a difference. So that work digging in, and in her case, uh involving uh others in her program and involving the constituents around the state and the region, uh, I think she was able to make some real significant progress for tomatoes for that that region of the United States, which we normally don't think about as being a tomato growing region.

Sam Humphrey 43:12

Yeah, that thank you for highlighting that reminder, Kurt. I'm doing my PhD right now, and I think it can be so easy to get down in the weeds of, oh, I have this problem right now with this sensor, and it just like just getting caught up on all these small things that you have to solve on your way to getting the PhD. But you're right that there can be a very large scale impact. You really do impact the people around you, the people you work with, and those collaborations into the future, as well as the research outputs that you put out that hopefully do benefit growers far, far into the future. I try to keep that one in mind.

Curt Rom 43:52

Yeah, well, science is a progressive thing. So, and I think this was a great example of uh of that dissertation that made a Difference. It was recognized as an award-winning publication, and now Amber's gone on to another institution where I'm sure she'll be making a difference as well. Samson, I enjoy the conversation with you. It's always good to catch up. I learned a lot today, to be quite honest. It was very informative as well as enjoyable. So this is Kurt Rome and my co-host Samson Humphrey. Thank you for joining Plants, People, Science. Thanks for listening. The ASHS podcast, Plants, People, Science, is made possible by member dues and volunteerism. Please go to ashs.org 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 45:00

This episode was hosted by Samson Humphrey and Curt Rom. Special thanks to our audio engineer Andrew Scheldorf, our research specialists, Lena Wilson and Andrew Scheldorf, our ASHS support team, Sara Powell and Sally Murphy, and our musician, John Clark. Thanks for listening.