A Berry Big Deal: Merging traits for taste and toughness

New research is exploring combining the best traits of traditional table grapes with muscadines to create disease-resistant, flavorful grapes consumers will love.
 
In this episode of Food, Farms & Forests, Dr. Margaret Worthington, associate professor of horticulture and researcher at the Arkansas Agricultural Experiment Station, explains the project she co-leads to create a new grape variety.

Worthington and an interdisciplinary team of 31 researchers from 12 institutions across the country are working on a research project to develop hybrids between two very different types of grapes: the classic table grape, Vitis vinifera, and the southeastern native, Muscadinia rotundifolia, better known as muscadine.

Muscadines have exceptional disease resistance and thrive in the Southeastern U.S., while Vitis vinifera grapes have the textures and flavors consumers love.

Worthington shares some history of efforts that began over a century ago to bring together the best traits from both grape types. She explains that one unique aspect of this research is the unprecedented level of collaboration between the traditional Vitis vinifera and muscadine grape breeding communities.

Worthington—who grew up enjoying the fruit in North Carolina—hopes to elevate muscadines to a nationwide “fifth berry category,” joining the ranks of strawberries, blueberries, blackberries, and raspberries.

This project is funded by a $7 million USDA-NIFA grant.


Related Links:

Vitis Vinifera and Muscadines: Grape Breeders Seek the Best of Both Grapes

USDA-Agricultural Research Service’s Plant Disease Action Plan for 2022-2026

USDA Invests Nearly $121M in Specialty Crops Research and Organic Agriculture Production


The Vitis x Muscadinia project is supported by the Specialty Crop Research Initiative, USDA-NIFA project award no. 2024-51181-43236.

Transcript

[00:00] Margaret:

I am very passionate about them. They're my favorite fruit. So, I would love to see them in the marketplace. I think they're really an exciting fruit for a number of reasons. People are always talking about like the fifth berry category, right? So you have strawberries, blueberries, raspberries and blackberries. And a lot of people are interested in, you know, what could we have as a new berry category? And to me, I think muscadine grapes are something that are really exciting.

 [00:31] Intro/Outro

Welcome to the Arkansas Food, Farms and Forests Podcast. The podcast bringing you the latest on food, fiber and forestry research from the Arkansas Agricultural Experiment Station, the research arm of the University of Arkansas System Division of Agriculture.

[00:45] Jenifer:

Welcome to Food, Farms and Forests. I'm Jenifer Fouch. Today we are learning about a research project to develop new grape hybrids that combine the best traits of Vitus vinifera, the traditional table and wine grapes, and muscadinia, muscadines. This research is made possible by a $7 million USDA grant, and the goal is to improve grape quality and disease resistance. To talk to us about this research is Dr. Margaret Worthington, one of a few scientists on this project. Dr. Worthington is co-directing this research. She's a researcher with the Arkansas Agricultural Experiment Station and an associate professor in the horticulture department. Dr. Worthington, thank you so much for being here with us.

[01:30] Margaret:

Thank you for having me.

[01:32] Jenifer:

So, the title of this research is at Through the Grapevine: Developing Vitis and Muscadinia wide hybrids for enhanced disease resistance and quality. And this grant is from the U.S. Department of Agriculture. It's a four-year project. 32 members on this from 12 different institutions. Can you talk to us about your expertise in your specialty, Dr. Worthington, and kind of how you fit into this project and what you are going to be focusing on?

 [02:01] Margaret:

Sure. So, we have six objectives in the project: genetics, breeding, pathology, quality and food science, marketing, and finally, production. And I'm leading the breeding objective. 
 
 Plant breeders kind of work with a lot of disciplines collaboratively. So, we have to have new cultivars that have the quality that's demanded by the industry, that are also quite productive and yield sufficiently, that have good disease resistance. And we have to work with geneticists to incorporate those tools into our breeding process. So, I think we on the breeding team have collaborations with everyone and almost every other aspect of the project also. 
 
 We're actually in a unique position here in the University of Arkansas Division of Agriculture, that we have had a table grape breeding program here since the 1960s. We've developed a number of cultivars that work kind of table grapes here over the years, and especially we've had a lot of collaborations with the private sector in Southern California, developing products like Cotton Candy grapes. 
 
The dream was always to develop an eastern table grape industry, but that's quite difficult to achieve because it rains here, and so it's hard to compete with production in in somewhere like Bakersfield, California, where you don't have the rain that causes cracking and disease pressures. 
 
 So, my predecessor, Dr. John Clark, actually shifted our focus a little bit away from table grapes to the original table grape from eastern North America, the muscadine grapes. So, we started crossing muscadine grapes in 2007 here. So, we have active programs in both grape, table grape, Vitis vinifera, and muscadine grapes here. So, I'm kind of involved in both aspects of that. Harold Olmo, who was the historically very important grape breeder at UC Davis, said that of all the wild grapes in the world, there's none that is the complement to Vitis vinifera of muscadine of muscadinia rotundifolia. 
 
So, muscadine grapes have all of these complementary attributes that would really help Vitis vinifera and vice versa. Vitis vinifera grapes have that great texture that everyone loves. They've got a stenospermocarpic seedlessness. They're very productive. They make nice wines. They have stable anthocyanins. On the other side, muscadine grapes have this great aroma. They've got like these floral, fruity, super grapey notes. They are very disease resistant to most of the major pathogens that affect a grapevine production around the world. And they also have interesting complementary traits in terms of like seasons. They're about a month later than muscadine grapes on flowering and on harvest. And they have a clean obcision scar. They at least can have a clean obcision scar so that you could harvest them individually by grape instead of having to harvest them on a racus in a little bunch like the grapes. 
 
So, there are a lot of really interesting traits that would make breeding hybrids between these two really interesting. However, it's complicated to actually do this because they have a different chromosome number. 

 So, some people say that Muscadine and Vitis are completely different genuses or genera. And some people would say that they are like sub genera. But there is a difference in chromosome number. Basically, chromosome seven on bunch grape segregates as two independent chromosomes in muscadine, exactly like a horse and a donkey. So, as you are aware, know, when you cross a horse and a donkey, you get a mule. And a mule is a nice hardy animal but largely sterile. So, we have the same problem that there is sterility of these first generation hybrids that we can produce. But we have been able to overcome this over time. They're these kind of rare individuals but have some partial fertility. And so you back cross them to vitis grapes or to muscadine grapes. You can restore that fertility over time. And bring in these traits.

 [06:16] Jenifer:

Would you say that is the biggest challenge then is that chromosome challenge?

 [06:20] Margaret:

You know, the difference in chromosome number is part of it for sure. But I think there are also some differences related to overall divergence or polymorphism across the genome. They're like super collinear. So, you know the genes and the chromosomes all line up in the same order. But you have these differences that can probably affect recombination and pairing in meiosis. So, you get more aneuploidy. That's a major part of what we're working with the team at Cornell on. I'm very excited to be working with Qi Sun and Wojtek Pawlowski at Cornell on understanding kind of what are the causes of sterility and how is recombination affected in these wide hybrids? And I think that's a really unique aspect of our project, that it has some kind of more basic science applications because what we learn in grapes and muscadine can hopefully be applicable to others working on developing wide hybrids and different crops too.

 [07:20] Jenifer:

So, can you give us an idea of the timeline? I know this is a four-year project. How does this project work, essentially on a timeline like that?

 [07:30] Margaret:

For grapevines and a lot of perennial fruit crops, the generation time is pretty long. So typically, from making a cross to releasing a variety, you can count on about ten years. So it's a long-term process. So, it's not like I can make a cross this year and expect to have a product out in four years, but we have a breeding pipeline, you know, in our program, we have been working on wide hybrids for several years leading up to this grant. 
 
We are also working with other grape and muscadine breeders from across the country who have some activities going on already. So, we're putting in variety trials with kind of existing muscadine fresh market cultivars and wine or processing cultivars, as well as some of these new hybrids that have been developed because there are already some, seedless muscadine lines that are on the marketplace. And we have hopefully new exciting products coming out in the next couple of years.

 [08:25] Jenifer:

Very cool. And why was this needed? Or where did this idea come from in the first place to combine the two? Where did the need to come from for it?

[08:33] Margaret:

Even 100 years ago, people recognized the value of bringing in disease resistance from muscadine to Vitis vinifera, and in bringing in some of these quality traits from Vitis vinifera to muscadine. 

So, there were breeders in North Carolina, Dearing, and Detjen, that were working in the 19 tens on developing these white hybrids, and some of the materials that are kind of the foundation for what we're using in this project were developed from those efforts. You know, 110 years ago. So, it's building on the work of Dearing, Detjen, and subsequent generations of breeders and the private and the public sector. 
 
So, this is not starting from scratch. I will say that you know, we have made a lot of achievements already. There's a disease-resistance gene called RUN1. That's a gene for powdery mildew, that is very, very important, that has already been introgressed from muscadine to wine and table grapes. And there are some released cultivars that are being grown in France right now that have the disease resistance gene and some other advanced hybrids that are in testing in the US. So, there's already been some achievements on that side. 
 
On the muscadine side, there's a private breeder, Jeff Bloodworth, who works with Gardens Alive! now. And he has brought in seedlessness from bunch grapes to muscadine. And those products are already out on the marketplace. But the whole process of developing these has been kind of slow, because it's largely been something that's been done with classical breeding without using molecular markers. So, it's not very precise how we are making these crosses and how we're understanding what we're doing. So, I think what I was excited to do with this project was take all of the things that we have learned about genetics from Vitis vinifera and extend them to muscadine grapes, and kind of work on using molecular markers to understand what we're doing and making these wide crosses, and help us to do it more precisely, more quickly and efficiently.

 [10:42] Jenifer:

So, this is something that the industry and experts in the industry and scientists have been looking at and wanting to do for a long time. And now you have the chance to. And more technology, more studies, more information, more data. And now with this big grant, more resources.

 [11:59] Margaret:

But I'll say to that another point I should make the Vitis community and the muscadine community have been working somewhat in isolation from each other. So, there is some collaboration, but there hasn't really been a large formal collaboration. So, you've had these people working on table grapes and wine grapes that have been trying to bring in disease resistance from muscadine grapes. And on the other side, you have muscadine breeders who have been trying to develop a muscadine grape that has a more palatable texture, that has seedlessness, all of these kind of traits that make it appealing to a broader audience. But you haven't had those teams working together in the past. 
 
So, what's really exciting about this project is that we are bringing together the best scientists that are working on Vitis grapes around the country, with all of the people who are working on muscadine grapes. And I think that's going to really help us to accelerate what we're doing.

[11:55] Jenifer:

Yeah, that's really cool. So, for the first time, we can say that now you we're kind of merging these two industries, or expertise, the two teams that had been working separately coming together now with this.

[12:09] Margaret:

Yeah. That is exactly right. There's been a very cool SCRI (Specialty Crop Research Initiative) funded project called by VitisGen that's in its third iteration now. And the VitisGen group have done a lot of work to develop molecular markers in Vitis vinifera and new strategies for molecular breeding and developing of disease-resistant cultivars. So, we are working closely with that team. It's a strong collaborative effort, and I think we're able to kind of build off what they have developed already, rather than trying to start from scratch.

[12:44] Jenifer:

As a scientist, as a fruit breeder, what is that like for you to to be a part of this?

[12:49] Margaret:

Well, I'm really excited that we got the project funded. We wanted to do something on Muscadine grapes for a while.
 
I grew up in eastern North Carolina, and it's an area where muscadine grapes are quite culturally important. So here in Arkansas, you'll see muscadine wines, but you will rarely see fresh market muscadine grapes at a farmer's market or at a grocery store in North Carolina. It's something that every fall, we look forward to eating the fresh grapes, and they've always been my favorite crop. So, I was really excited when I came here and I interviewed at University of Arkansas to see that we had a muscadine grape program, and that's something I could work on because I am very passionate about them. They're my favorite fruit. 
 
So, I would love to see them in the marketplace. I think they're really an exciting fruit for a number of reasons. They're adapted here in the southeast. They're native to the southeastern US, so they grow well in kind of our erratic climate, where it'll be 80 degrees in February one week, and then the next week it'll be like a high of 30. So they will like, you know, they're adapted to kind of the fall-spring, to the rainy conditions. So they're very disease-resistant. So, they're a great crop for growers in our part of the world. They also are really interesting in terms of season, I think that a lot of our producers of fresh berries for blueberries and blackberries, they're very busy and they have a lot of fruits coming to the marketplace in early summer. But this is a kind of a fall crop. So here in Arkansas, muscadine grapes are mostly a September crop. So, it's nice in terms of labor utilization for our growers, I think. 
 
I mean, people are always talking about like the fifth berry category, right? So you have strawberries, blueberries, raspberries and blackberries. And a lot of people are interested in, you know, what could we have as a new berry category? And to me, I think muscadine grapes are something that are really exciting.
 
It's something most people have not tried as a fresh grape, or if they have tried, they've tried wild muscadine and the new cultivars, especially the new seedless cultivars, are a totally different eating experience. They still have that great flavor that people love, but with, a texture that is a thinner skin. You know, people say that the old skins on screens are like shoe leather, and then the flesh is like an oyster. So that's not very appealing. And then they have these big bitter seeds. 
 
So, they have these great attributes, this great flavor, but with this texture that is off-putting to a lot of people. So, it's exciting that we have a better texture now. I think it's something that would be appealing to a lot of people and would be a great new commodity. So I'm very passionate about helping to build the industry, and to me, this big collaborative project sets us up to be successful and to build that industry.

 [15:52] Jenifer:

So, it's coming full circle for you. Something you grew up loving now in your career, here's this huge project you get to be a part of and like you said, help build the industry.

 [16:01] Margaret:

Yeah, I think it's interesting from a personal perspective that I want to see muscadines on the supermarket shelves all year round. I think it's also exciting from a scientific perspective. Some of the issues that we're tackling are just really interesting. 
 
It's really cool to work on something that there are a lot of resources for grapes, but not that many for muscadines, and so we can catch up very quickly I think. And fun to work in this big interdisciplinary team, particularly with my co-PD Renee Threlfall in Food Science and with Scott Lafontaine over there to kind of now understand what is it about the flavor of muscadine so that people like, are there any things that people don't like so that we can do more targeted breeding to make it appealing to a broader audience? 
 
I love the interdisciplinary aspect of the project. And I love that it can potentially develop and result in the development of new cultivars that will be helpful for both the grape industry and the muscadine industry.

[17:00] Jenifer:

When or how did you know that you were going to be a fruit breeder, that you wanted to go into this industry?

[17:09 ] Margaret:

I think when I was doing my Ph.D., I took a class, that was kind of like a careers and plant breeding class where we went and visited lots of programs with different crops in the public and the private sector. And as I was learning about the different programs, I was thinking, okay, I think I would like to be a university breeder. I would also like to be a university breeder where people are really growing the cultivars that I produce, where you're having a real-world impact. So, I wanted a very applied program. 
 
I had actually learned about the University of Arkansas Blackberry Breeding program when I was a graduate student, and I thought, oh, wow, interesting. So, when this position came up, I was really excited to come and apply for it, although I didn't know that much about the program. 
 
So, I had a really great opportunity, I’ll say, because I didn't have a lot of experience in fruit before I came on board here. I had almost six years of overlap with Dr. John Clark, who was our veteran breeder here. He's famous among fruit breeders. He's a wonderful guy, really innovative in terms of how he does breeding, very commercial focused, did a great job with intellectual property management and helping us to develop a lot of public-private partnerships that have been really important in getting our material out there and used around the world. So, that mentorship with John Clark was really important to me. 
 
But I think it's also been really good that I worked on a lot of different crops before I came on board here, that seeing how row crops are bred, seeing how Brachiaria and forage grasses are bred, has given me, I think, insight into how to apply different tools and strategies and to a fruit breeding program.

[18:57] Jenifer:

So, at the Fruit Station, the blackberry breeding program is the flagship program. let's talk a little bit about that.

[19:04] Margaret:

Yeah. I'll just give, a little bit of history. The Arkansas Fruit Breeding Program was established in 1964 by Jim Moore. He was an Arkansas native, and he established programs in a bunch of different crops like strawberries, apples, blueberries, blackberries, peaches and grapes. And fortunately, we don't work on all of those anymore because I would lose my mind. But we do still have active programs, especially in Blackberries. That's kind of our flagship program. And then also in peaches and grapes and muscadine grapes. So it's really kind of nice because they are kind of spread out where we start with blackberries first thing in the season, and then we move on to, to grapes and then muscadines as the season progresses.

[19:51] Jenifer:

What would be maybe a piece of advice or something you have learned that you would tell someone starting out their career or maybe interested in this industry?

[20:02] Margaret:

I think there are so many opportunities out there for young people who know about applied plant breeding, who can work in the field and also handle molecular data. A lot of people are interested and just kind of the science side of aspect of what we do and interested in lab work and maybe bioinformatics, but not interested in going to the field. I think there are a lot of opportunities out there for people who can do both, and I would encourage everyone to find a graduate program where there really is applied cultivar development happening, and to make sure that you are involved in all aspects of the program that you're helping with crossing, you're out there in the field, you're understanding what you're doing. 
 
My Ph.D. advisor at North Carolina State, Paul Murphy, was like very hard-driving and had us out there like driving the combine, working the planter, like understanding every aspect of what we did in the breeding program. And it was very tough, but it gave me a ton of confidence that I was ready to lead a program. 
 
So, I think that would be my main advice to just make sure that you are out there involved in as many aspects of the program that you're working in as possible and not just focused on your own dissertation research.

 [21:25] Jenifer:

Very good. And what is your favorite part of your job?

 [21:27] Margaret:

I have two answers to that question. First, I think I do the perfect mix of inside and outside work. I love to be outside. I like to be in the field among the plants. But come like October, I'm also like, I'm ready to spend five months in the office. That was a lot. So, I think that I like that aspect of what I do. I also — my favorite and least favorite aspect of my job at the same time is that I feel like I'm a university professor and a small business all at once, that I love, that we have all of these public private partnerships where we really are seeing what the industry wants, what growers want, and we are developing products and putting them out there on the marketplace. And I think that's so fun and an exciting part of what we do. It's also hard to manage everything at once, but it's an abundance, overabundance of good things. How's that?

[22:30] Jenifer:

Well, thank you so much, Dr. Worthington, for taking the time to explain this research and a lot of your career and your work with us here on the podcast.

 [22:39] Margaret:

Thank you.

 [22:40] Jenifer:

That was Dr. Margaret Worthington, associate professor in the horticulture department and researcher for the experiment station, talking to us about her research project to develop new grape hybrids combining Vitis vinifera, the traditional table and wine grapes, and muscadinia, muscadine. Thanks for listening. I'm Jenifer Fouch. Don't forget to subscribe!

 [23:03] Intro/Outro

The Arkansas Food Farms and Forest Podcast is produced by the Arkansas Agricultural Experiment Station, the research arm of the University of Arkansas System Division of Agriculture. Visit aaes.uada.edu for more information.