Wine

Is CRISPR the solution to controlling the pest plaguing California’s wine industry? In this episode, we take you to a lab where researchers are using CRISPR to genetically modify a frightening insect responsible for spreading a bacteria and killing vines.

Clarification: While Dr. Tim Martinson holds healthy skepticism about the hype around CRISPR technology now, he acknowledges that it's just starting to be used and he believes it will become a valuable tool – one of many in a grape breeder’s toolbox.  

Resources

• To learn more about wine grape breeding techniques, we highly recommend reading up on Dr. Tim Martinson's research on the subject here and here.

Interviews

• Dr. Tim Martinson, Senior Extension Associate (retired), School of Integrative Plant Science, Horticulture Section, Cornell AgriTech
• Dr. Peter Atkinson, Professor of Entomology, University of California, Riverside
• Dr. Linda Walling, Professor and Geneticist, Botany and Plant Sciences, University of California, Riverside

Credits

A CRISPR Bite is supported by the Jean Monnet Network, which is funded by the Erasmus+ Programme of the European Union through the GEAP-3 Network of scientists. More about our project here. This podcast does not reflect the views of our funders. 

This podcast was co-written and hosted by Dr. Lauren Crossland-Marr. Our executive producer is Corinne Ruff. She co-wrote, edited and produced the show. Jake Harper edited this episode. The show was sound designed and engineered by Adriene Lilly. Aaron Crossland made our theme music. Rachael Marr designed our logo.  Legal support from New Media Rights and marketing help from Tink Media. 

Thank you to the GEAP-3 team! Special thanks to Matthew Schnurr, Klara Fischer, and Glenn Stone for their support and advice on this podcast. 

Leave a 5-star rating and review of this episode on Apple podcasts to help us spread the word. Have more to say? Email us at acrisprbitepodcast@gmail.com. Follow for updates on Instagram @acrisprbite

Transcript

Lauren Crossland-Marr: Okay. Cheers.

When I'm not teaching classes or writing academic papers, I love to study wine. Of course, it's fun to just drink wine, but I'm learning that there's so much more to it. My husband, Aaron, and I have been taking classes to better understand the nuances of flavor, texture, and taste. And the history of the wine we drink.

We recently tasted an orange wine from Vermont and contrary to the name, it's not actually a wine made from oranges. Orange wine is made by leaving the juice in contact with the grape skins, which turns the wine and orangish color. We got a little nerdy describing the wine to each other. I think our teacher would be proud.

It's a hazy wine. What'd you say? Yeah, it looks like unfiltered.

I'm getting like a green apple, grapefruit, lemon, lime. Um, what are some of the flavors you're getting? I don't know, this is weird, like stone fruits? 

Yeah, some stone fruits, I'd definitely get that. 

I have an unpleasant aftertaste that I can't get out of my mouth. Okay. I don't know, I think if anything I'd say...Apricot is like, the overarching for me. With maybe some floral. 

Oh yeah, I can definitely smell apricot. Like rose. Lychee? 

Sure. 

Okay. 

Actually maybe, I don't know. A little bit, I don't know. 

It's always lychee to me. It smells a little bit like Japanese ramune. 

Oh yeah, it does actually. Like that ramune drink that has a little ball in it.

This wine was really different from what we'd normally drink. That's because it's a variety that's bred with varieties native to the U. S., and that's really uncommon in the wine industry. We live in California where more than 80 percent of the U. S. wine is grown. Think grapes like Cabernet Sauvignon, Chardonnay, and Merlot.

Something I recently learned in class is that these are all popular European grape varieties, and they're facing a huge problem in California that CRISPR might actually be able to solve. 

This is A CRISPR Bite, and I'm your host, Dr. Lauren Crosland Marr.

So far on the show, we've only talked about CRISPR edits on plants. But this time we're diving into the story of an invasive insect that is threatening the success of California's nearly $46 billion wine industry. We'll take you to a lab where researchers are using CRISPR to edit the genes of insects in the hopes of reducing the spread of a disease.

Before we get into the insect that's ravaging California's vineyards, I need to walk you back a few centuries to talk about how European grapes ended up in the US and why they've always been so hard to grow here. 

Name a U. S. grape variety that you drink and I can almost guarantee it comes from Vitis vinifera, a species of grape shaped in Europe thousands of years ago and upheld as the cream of the crop.

This goes for both red and white wines, like Cabernet Sauvignon, Pinot Noir, Chardonnay, Riesling, and on and on. The market for wine is based on the consumer knowing these varieties. I spoke with Dr. Tim Martinson about this. He's a trained entomologist, someone who studies insects, but he spent most of his career working with farmers to create sustainable grape and wine programs.

Tim says Vitis Vinifera is a fragile plant that requires an incredible amount of human energy to make it thrive anywhere, and especially in the U. S. 

Tim Martinson: There was, uh, maybe three centuries of failures, okay? So initially, you know, people like Thomas Jefferson wanted to grow Vitus vinifera in the United States. They didn't know about grape phylloxera, so they would plant them, they would fail. 

Lauren Crossland-Marr: Jefferson's vines didn't take because, although he didn't know it, the vine was not resistant to native pests and fungi. When European settlers arrived, they encountered native U. S. grape varieties, like Vitis rubistris. The vine is immune to native pests and fungi.

But the U. S. varieties never took off because starting in the 19th century, French business interests asserted their wine is the best in the world. This quoi built the global market for French and eventually European wines. In terms of ecology and natural resistance, planting European varieties across the globe was not the best decision.

But economically, that's how, ahem, Europeans created the market. The U. S. had no choice but to make it work, but the problem is that more inputs and better technology were needed to keep vines alive in places they don't belong. The things farmers have to buy, like fertilizer and pesticides, are called inputs.

As time goes on, farmers have to buy more of these things to grow the same amount of crops from year to year. This is what social scientists call the technology treadmill. And that's where CRISPR comes in today. Some researchers are hopeful that it's the technological fix we need to keep the wine industry going strong in California, despite these age old challenges.

Tim, the wine guy, isn't super familiar with CRISPR technology yet, but he lumps it in with GMOs. And based on his experience, he says that kind of technology is overhyped. 

Tim Martinson: There's a history of people involved in genetic engineering making very broad promises about them and then the reality, and this happened with us with, uh, you know, we had some GMO chardonnay grapes that they put a chitinase inhibitor in.

Lauren Crossland-Marr: That's a fancy way of saying they added a gene that wasn't typically found in the Chardonnay grape genome, making the plant resistant to the fungus that causes powdery mildew. 

Tim Martinson: And we're thinking, well, that could be the cure for powdery mildew. And you know, it just didn't work out. It just didn't live up to the hype. I don't know how many seminars I've been through where in proposals I've read that say, well, here's the important stuff we're doing and this is going to lead to X. And sometimes those are kind of glib. 

Lauren Crossland-Marr: Tim is suspicious that gene editing tech like CRISPR will save the U. S. wine industry. He's more interested in small producers in lesser known states like Wisconsin and Minnesota, who are growing hybrid grape varietals.

The University of Minnesota developed a few of these hybrid grapes in the late 1990s and early 2000s. They blended varietals native to the U. S. with others to create new grapes that would have a better shot at growing in the U. S. They were developed to have regional benefits, notably to be more resistant to diseases without extra pesticides.

And some are better for growing in colder climates like Minnesota and Wisconsin. La Crescent, Marquette, and Frontenac are just a few examples of these that appear on wine bottles. But producers growing these varietals are small potatoes compared to California's enormous wine industry. So what if CRISPR is the answer to keeping foreign grapes here?

I'm inside the lab in Riverside, California, about an hour and a half east of Los Angeles. Researchers are using CRISPR to genetically edit the insect plaguing the state's wine industry. So, um, this is where we actually do the experiments. It's a lot of microscopy, so these are dissecting microscopes. This is where we do a lot of screening, a lot of setting up the eggs.

Peter Atkinson: And then, um, this, this here is actually the microscope we use to inject, um, whitefly and, um, sharpshooter and mosquitoes and, um, other things. 

Lauren Crossland-Marr: I'm at the University of California, Riverside campus to talk about a gnarly looking insect known as the glassy winged sharpshooter. It's a mouthful of a name, I know.

I'm walking through the lab with entomologist Dr. Peter Atkinson. He and a plant geneticist, Dr. Linda Walling, have been working on modifying the sharpshooter using CRISPR for years. Should we follow you? He takes me into a small room where there's a chamber on a table. Inside that enclosed glass box, you can see teeny tiny eggs that are growing on a flat leaf.

Peter Atkinson: Oh, there are. But they're probably not, um, they a sorghum leaf. And we've cut that off, and this is actually the, the egg mass. And so, it's one egg mass, I imagine, that they're all laid up in that direction. Oh, this it's not what I imagined, you know, I thought. Well, these are embryos, right? Oh, yeah. I just want to make sure nothing's hatched. Okay, so that's on the sorghum, and you can actually see the mother. There's later mass. Yeah. And, you know, like, they're longitudinal, so they're facing, they're pointing towards you and me. Yeah. Does that make sense? Yeah. I guess, I can't see, like, there's probably about a dozen there. Do you know a dozen? Oh, yeah. So they are three days old, so there's a day or two from when we can actually screen them for an eye color, if that's what the experiment was, and they'll hatch in, uh, three days. Well, they'll hatch in four days.

Lauren Crossland-Marr: We leave the lab and move to a conference room where it's a little quieter to talk about the problem Peter and Linda are trying to solve for using CRISPR. It turns out this is a long standing problem. The glassy winged sharpshooter has been devastating California vineyards for about a hundred years.

It's originally from the east coast of the U. S. and is invasive out west. The insect doesn't kill grapevines directly, it's not like locusts that ravage crops, but it does carry bacteria, which causes something called Pierce disease. Once a vine is infected, it cannot be cured, so farmers have to eradicate the whole area, which is a costly move.

Authors of a 2014 article in the journal California Agriculture estimated the sharpshooter is costing California's vineyards more than 100 million a year. The glassy winged sharpshooters are the villains in this story, and they definitely look the part. Let me paint you a picture of just how creepy these crawlers look.

They're smaller than a dime, but up close they look a lot like cicadas. They have dark brown bodies, long wings, and small heads with dark eyes. I definitely wouldn't want them flying anywhere near my face. They also make some pretty surprising mating and male rivalry sounds, almost like a motorcycle speeding down a highway.

That sound was from a video produced in 2015 by USDA research entomologist Dr. Rodrigo Krupner. He studied the mechanics of how the sharpshooters make sound, in hopes of finding ways to control the pests through researching their communication. But what UC Riverside researchers Peter and Linda are looking at has nothing to do with the insect sounds.

They're more focused on how the glassy winged sharpshooter transmits bacteria. Linda says their research starts with focusing on the insects physical traits, or how they look. 

Linda Walling: We're always comparing it to really beautiful white flies. They're very delicate and they're very, very symmetrical and quite appealing, whereas the glassy winged sharpshooters are... I think you have to love them to appreciate the distractions. 

Lauren Crossland-Marr: And we've heard a lot of people do not love them because, as you mentioned, they carry the bacteria that causes... Pierce's disease. Um, and so I'd like to know, you know, what is the big deal here? You know, why, um, manipulate them with CRISPR, especially in context of the important wine industry here in California?

Peter Atkinson: So the conventional approach is to control sharpshooter. It's not dissimilar to what conventional approaches are to control other insect pests, which is, um, use of chemical insecticides and they come at their own cost. First of all, inevitably insects become resistant to it. 

Lauren Crossland-Marr: Peter goes on for a while about this, but the gist is that, typically, farmers use pesticides to control the glassy winged sharpshooter population. But as insects become resistant to those chemicals, farmers have to buy more and more to keep away pests. And those chemicals end up killing beneficial insects, like honeybees. But what CRISPR brings to the table for the first time in the genetic control of insects is specificity. Peter says CRISPR is a boon in technology that allows him to make changes to the sharpshooter directly.

Theoretically, this would mean farmers wouldn't have to use pesticides for the sharpshooter problem. Peter and Linda aren't trying to eradicate the sharpshooter from California. Although, side note, they could totally design an experiment to do just that, despite some of the ethical concerns that raises.

For now, though, their plan is to change its genes so that it would no longer be able to carry the bacteria that causes Pierce's disease.

Linda Walling: Like I said, we're still in the phase of technology development and demonstrating that we can Find one solution for a super big industry here in California because it's not just the wine industry, it's our table grapes, it's our raisin industry, and...

Lauren Crossland-Marr: Their research started with a simple proof of concept. Changing the sharpshooter's eye color and wing shape. It was a big success. The two scientists co authored a paper detailing their findings last year in the journal Scientific Reports. Changing the eye color is just the starting point in learning how to change the physical characteristics of the insect.

Eventually, they want to use CRISPR to turn off the gene that is responsible for the part of the insect that carries the bacteria causing Pierce's disease. The mechanics of this are not well known yet, but once they figure it out, they hope they can release the lab created glassy winged sharpshooter into the wild California population.

This sounds pretty cool, right? But our producer Karen Ruff, who helped me tape this interview, wondered about the potential downsides of this CRISPR experiment. 

Corinne Ruff: So, I mean, this podcast is for people who may be learning about CRISPR for the first time. And I think for some people, when they hear about a new technology, they're like, whoa, whoa, whoa, what are we doing here? We're changing insects. We're changing their eye color. What do you say to people who have hesitation or concern about, do we really need this? Is this safe? Is this the right way to go forward? Like, should we be concerned about this? 

Peter Atkinson: I think it's totally reasonable to question in advance. That comes along, you know, engineering, scientific. I think that's totally understandable. What's good about this technology? Well, it's, uh, very specific. So people would be concerned about the label of genetic engineering. I think we both know what the pros and cons of those arguments have been. And yes, we are gene editing, you know, these genomes, but this technology enables us to do it precisely. So particular gene can be mutated that eliminates the pestiferous nature of that insect. As we talked about sharpshooter, well, we can do it. Can we demonstrate that there are no other consequences in terms of what the, there are no changes elsewhere in the genome that we didn't mean to make, but we can do that with genome sequencing. Can we make it specific? to the target population in this particular area of California. Actually, we could. We would need more data about population genomics of the pest species around there. 

Lauren Crossland-Marr: Peter isn't alone in that opinion. He's really optimistic about the potential benefits of CRISPR. But he does think researchers should be cautious and work with the public to address concerns.

And one of the biggest worries from critics is that CRISPR technology can result in unintentional off target changes in the genome, something we will explore at length in the next episode. But basically, this means there may be changes we aren't expecting. And that's a big concern if you release a lab created population into the wild.

But like Peter, I'm not thrilled about pesticides, and one way to avoid these chemicals is to release a sterile pest population into the environment. And this has been done before. Scientists did it in the 1950s with the invasive screwworm fly. It's a fly that burrows into the flesh of warm blooded animals and infects them.

Beyond being incredibly gross, it caused huge problems for the meat industry in North and South America. Scientists found they could expose male hatchlings to radiation to make them sterile. Then they released the sterile screwworm flies so they could breed with the wild population. Since the females only mate once, any fly that mated with one of these sterile flies couldn't reproduce.

Eventually, this method greatly reduced the pest's population. This is similar, in a way, to what Peter is hoping to do, but not to reduce the sharpshooter population, just to make it so they aren't spreading disease everywhere they go. This whole experiment really stands out to me as an interesting CRISPR use case.

That's because... Unlike other examples I've talked about on this show, like tomatoes and soy products, the gene edit this time around isn't being done on the crop, but on the pest. And that's not been typical in the decades since the screwworm fly experiment. Instead, companies like Bayer, which now owns Monsanto, developed pest resistant seeds using GMO technology called Bt, or Bacillus thuringiensis seeds.

It's important to know that the Bt seeds that Monsanto developed did perform well, but only for a few years. In the long run, these varieties required additional pesticides because pests soon became resistant. And this wasn't the only issue. The toxins produced in the plant meant to deter the target pests could negatively impact other insects in the environment, probably most famously the monarch butterfly.

And for farmers, the seeds weren't a perfect solution either. They were expensive, and you had to buy them every year because they were protected by intellectual property laws. Remember that technology treadmill I talked about earlier? Yep, that's what's happening here. Basically, once farmers started using GMO seeds, it was really hard to break away.

And you can see why big agritech companies previously were financially incentivized to modify the seeds, and not the insects. They had built in long term customers. But in the case of the glassy winged sharpshooter, scientists are trying to come up with long term solutions that don't put the financial onus on farmers.

This seems way better for farmers. And that also makes a big difference to me. But is it still the best way to solve the problem? I think I'm in the same camp as Tim, the wine guy you heard at the beginning of the episode. From my perspective, CRISPR is being used to solve a problem that humans created.

It's another band aid solution to a systematic issue that In the long term, needs more upheaval than just a quick technological fix. But consumers have the power to do something about this. We have the power to make choices that support more sustainable practices. Our purchasing power could redirect the market towards forgotten Native U.

S. Great parietals that will stand a better chance at facing disease and pest on their own. And that's actually starting to happen in states that aren't as well known for making wine. I know, I know. European wine is amazing. I used to live in Italy after all. But hear me out. Next time you're choosing a bottle for dinner at a friend's or date night, Consider giving Marquette, Frontenac, or La Crescent a try.

Let's incentivize grape growers to plant grapes beyond varietals that are just fetus fenifera. Let's change the demand for European varieties, because these varieties are economically fragile and ecologically the problem. And let's have fun doing it.

Remember that wine I tasted with my husband at the top of the episode? It was made with the La Crescent grape, a grape that's made from varieties native to the United States. It's from Vermont, not California, which is a big bummer. I'd love to try varieties created in my state. But California's big wine industry is still so economically dependent on European varieties that there just isn't a market for growers to make big quantities of native grape wines.

I don't know about you, but for me, the best wines are the ones that get us talking, and this one certainly did that. I can't say it was the best tasting wine I've ever had, but the flavor did spark a surprising amount of super nerdy wine talk. Okay, so you'd say this is a... I'd say length or intensity. This is an acceptable one.

It's an acceptable one. Yeah. But I think it's really good that it's from Vermont, which is not where you have, it's not a region that's easy to grow grapes, so. So yeah, how much was this? Twenty five. Twenty five bucks for USA made wine, eh? Yeah, it's not bad. Not bad at all. So for now, I'll pour myself another.

Did this episode make you rethink the wine you drink? Leave us a review and let us know. And if you know a fellow wine enthusiast who might be into this nerdy wine talk, share this episode with them. Subscribe to A Crisper Bite wherever you get your podcasts. 

CREDITS

A Crisper Bite is supported by the Jean Monnet Network, which is funded by the Erasmus program.

Program of the European Union through the Jeep three network of scientists. This podcast does not reflect the views of our funders. This podcast was co written and hosted by me, Dr. Lauren Crosland Marr, our executive producer is Corinne Ruff. She co wrote, edited and produced the show. Jake Harper edited this episode.

The show was sound designed and engineered by Adrian Lillie. Aaron Crosland made our theme music. Rachel Marr designed our logo, legal support from New Media Rights and marketing help from our friends at Tink Media. Thank you to the Jeep three team. Special thanks to Matthew Schnur, Clara Fisher, and Glenn Stone for their support and advice on this podcast.