Talking Biotech 364 - Purple Tomatoes and Health - Dr. Cathie Martin === Kevin Folta: [00:00:00] Hi everybody. And welcome to this. Week's talking biotech podcast by collabora. Now genetic engineering of crops has been around for something like 25 years. We've seen the benefits for farmers. We've seen benefits for the environment. But innovations have been confined mostly to large scale agronomic crops, things like corn or soy canola, sugar beets, cotton, and that's because the regulatory climate is so arduous and expensive that companies can only afford to commercialize big acreage crops, at least using standard genetic engineering technique. And I know some of you out there are screaming papaya, and yes, Hawaiian papaya is our stellar example of how biotech traits can protect the industry from in this case, a destructive virus. And this goes way back to the 1990s. The effects of the arduous system have really been felt ever since, especially on smaller horticultural [00:01:00] ops. We also know there's a non Browning trait that's in apples. So we know that exists, but that's a really nice example of an end point consumer trait. And hopefully they'll do the same with avocados, cuz I wanna make some guacamole that I don't have to eat all that one first day. , but despite these benefits to the farmers and environment innovations that directly target the consumer really have not been pursued. And that's a bit ironic because the very first GE crop was a tomato. A product that really failed where it mattered, that is in winning consumer hearts and minds and appealing to consumer preference. It didn't deliver on what it set out to do. And unfortunately kind of changed the tone for approval of these like regular old horticultural crops that most of us consume whole on a daily basis. So today we're going to go back to the future. As a tomato has passed [00:02:00] some levels of deregulation and may be available in the United States. Very soon today, we're talking about purple tomatoes. So today's guest is professor Kathy Martin. She's a professor of plant sciences at the John Endis center in Norwich, England. So welcome to the podcast, Dr. Hi. Yeah. Thank you very much for joining me. I've wanted to have you on forever, mostly because I've known of your work, my entire scientific career, and you have so many interesting projects that are going on in the laboratory that have really important. Applications whether it was you know, tomatoes that were genetically engineered to combat Parkinson's disease or, or, you know, so many different projects that are happening. So thank you very much for joining me about purple tomatoes. my really a pleasure. Yeah, this is great. So for many people, this invention of a purple tomato, it's a solution looking for a problem. And can you give me a synopsis of some of the claims of connections [00:03:00] between these purple plant pigments and human health? Cathie Martin: I think that it's hard to claim that there are absolute slam dunk. Experiments that demonstrate the health benefits of science. We're talking about a food here or the content in foods rather than treating them like a drug. So, but it, there was certainly before we started the, to make the purple tomatoes, there was certainly evidence that purple. Fruits and red fruits, which are also contained anti science had health benefits. And that's from the idea that berries are very good for you. I'm sure everyone has seen some of the data supporting the consumption of Berry rich diet. And of course there's even a Institute in North Carolina devoted to, to blueberry, I think. And the health benefits of blueberry. So. Yeah. And I think that one, actually, one of the experiments that we did when we first described the [00:04:00] purple tomatoes gave some actually pretty direct evidence of the health benefits in that when mice that were prone to cancer were fed. Their diets supplemented either 10% Dr. Dry weight with purple tomatoes or 10% red tomatoes, the cancer prone mice live 30% longer on the, on the purple tomatoes, supplemented diet. So this was one of the first experiments that really could use foods isogenic foods to, to, to show a health benefit of a particular compound. And the field has grown since then. Kevin Folta: Yeah. When you say Cogenic, you're just comparing the ones that have the genetic change versus the exact same tomato missing that genetic change. Absolutely. Cathie Martin: That's right. And I think that that was an innovation in the field because nobody really did. I mean, people went down and bought food from the market , which is not. So, and they'd prepare compare maybe best of red cabbage with a, a, a green cabbage. But yeah, we actually knew [00:05:00] that they were genetically identical except for the production of signin. So, Kevin Folta: yeah, so this was, this was an apples to apples, oranges to oranges. Tomatoes tomatoes. Right? so, but if we look away from the human health benefits and talk about the potential influences on the plant itself, if you are overexpressing genes or changing genes in a fruit, how does that affect things like yield or maybe disease sensitivity, or maybe an aspect like post harvest quality of the. Okay. So, Cathie Martin: There's two answers to this. The first was that we were smart and that we wanted to make the, just the fruit purple. So we used a, a specific promoter that would just switch on the answer sign-ins in the fruit because we didn't want to have a major impact on. All of the rest of the metabolism that's going on in the plant. We knew from preliminary work in tobacco, that if we made very high levels of Ansers in, in the whole plant, it could really severely [00:06:00] impact growth, mostly because the plants didn't get enough light. And so they were very But so we switched it on just in the fruit and because the promoter that we used directs the synthesis of Ansy is very latent fruit development. After all of the fruit doesn't really impact yield at all. So it's just a switch, right? At the end, you have to imagine that a fruit is a sort of it's. An open system in the, if it doesn't have enough intermediaries to, to do its final metabolism, it can import more from the rest of the plant. So no, in fact, no effect on yield, what was completely unexpected. And the second half of the question was that we found that. The high Anth signin producing tomatoes were much more re resistant to infection by Petri. So that's gray mold and also that they had a longer shelf life. And this seems to be associated with the antioxidant or free radical scavenging properties of Anin. So they have double the shelf life, so that. [00:07:00] An unexpected bonus. Well, Kevin Folta: one of the mistakes I made here is I didn't ask you what are the specific pigments and, and so let's start out with, well, what is Ansin? We've mentioned it a few times now, but just for people who maybe are from animal biology, what is this stuff? So Cathie Martin: this stuff, it's, it's basically they're basically derived from phenyl OIDs that we might call 'em polyphenols. They're they're a type of flavonoid if you want to become even more specific in terms of biochemical classification and they are the pigments that are color most flowers and some fruits. So they provide. Blue purple red colors in many, many plants. So the red in strawberry fruits and the, the red in roses and almost most of the most common pigment in higher plants and in our crop species as well. They're present in red cabbage and in eggplant and. Trying to think of more, but [00:08:00] all Kevin Folta: the berries, all of grapes and purple grapes. And, Cathie Martin: and they come in in quite in different chemical structures. So, and this affects their, their, their color. So the, the slightly different chemical composition, if they make red pigment, or if they make a purple pigment or the, and the, all the blues that you see in nature are also due toy. There are some other red pigments in plants carats, but they're relatively minor, especially for flower color. Kevin Folta: Yeah. So Ansin are a class of molecule where there's different versions of Ansin or different modifications on that basic skeleton. Yeah. That dictate the final color in the specific food. So, yeah. And also maybe their antioxidant properties or bioavailability. Cathie Martin: The, there are lots of arguments about bio availability. They don't hang around. long in once you've ingested them. They can be detected in [00:09:00] plasma. Ayin about four hours after consumption by humans, but they disappear pretty quickly. And so there have been hypotheses that they don't. Workers and the signin, it's their metabolites that are the active components in promoting health. I'm not sure that that's exactly true. I think we, our understanding of how health benefits work has expanded enormously since the contribution of the microbiota. That's the gut. Microbes in your gut, how they behave. They modify that a lot. And we know that anti sinin can impact the composition of the microbiome. So if you eat a lot of antis, you have a different composition which is high in what. Euphemistically called good bacteria. And these, these may promote better metabolism of, of your, the food that you digest. So as part of the mechanism may be before they're even absorbed, but yeah, they have, they, [00:10:00] so the by availability is generally reported as low, but they are metabolized to phenolic acids, which have antioxidant properties too. And it may be that they don't have to. Actually bio available to have a major impact on health. Kevin Folta: Okay. That's really good. I, so if we talk about the genetic engineering of the purple tomato , we can go back to, you know, I've, I've studied purple pigments for years, just because they are outputs of light signaling pathways and I've studied light my entire career. And we've, you know, always talked about CCO CCO. So phenal ammonium LIS all the enzymes of that pathway. Is the purple one made, like, what is the enzyme or what are the enzymatic steps that were added to shunt more of substrate into this purple into a purple tomato. Okay. Cathie Martin: So the. Purple pigment that is made made in the purple tomatoes is also made in other parts of the plants [00:11:00] naturally. So if you don't water your tomato plants, you'll see that the Leafs start to look a bit stressed and go purple quite often as they do in migraine house. So so. Tomatoes can make purple Anin through all of those enzymes that are naturally in the genome. The only difference with the purple tomatoes is that they don't have the transcription factors that induce the, in the Anin biosynthetic pathway active in the fruit. So what we did was we added genes encoding. Regulators are switches that switch ony biosynthesis so that they were switched on at a very late development stage in the fruit in fruit ripening. Kevin Folta: Okay. So these are normally present genes that are even obviously in the fruit because they're in the DNA, but you're using a different control mechanism to turn them on late in, in, in plant, in fruit development. Yeah. Cathie Martin: And you can see it. [00:12:00] So. The germplasm of tomato has some natural variance where you can get purple skinned tomatoes. And there's these, this trait is caused by the same transcription factors in wild species of tomatoes. I think it's Salani Chie and Salani like a Peruis that have that they're able to produce sign in the skin of, of their fruit because they don't make red. So generally the red lycopene is exclu is mutually exclusive with the production of purple pigments, but through Integrion some varieties like indigo rose and sun black have been produced by bringing in genes from wild species, which encode transcription factors that switch on and signin biosynthesis, but just in the skin of the tomato. What we've done is exactly the same trick but done it by genetic modifications. So we've, and [00:13:00] now we are a by using the specific promoter that we use, we're able to make Ansers throughout the fruit. So that there's really a lot more Anine than in any Integrion line that can be produced. That's Kevin Folta: pretty neat. So what is the Bo bottle? Iny and synthesis that's opened up or is it a whole series of steps that are opened up with this transcription factor? I think Cathie Martin: it's just the, it's just the, the transcription factors that regulate Anin biosynthesis Maor are expressed at pretty low levels. Uh, And generally only under stressful conditions. I mean, Anin are used to protect from light stress as I'm sure you're aware. And they filter out their, the light in the visible range. So when plants are stressed, then light stress becomes even more of a problem because of photo oxidative damage. So they're produced in leaves to protect the photosynthetic machinery under. No. Very Kevin Folta: good. So this is all pretty cool stuff. [00:14:00] Was this done just using a standard transgenic approach or was there, yeah, this Cathie Martin: was done. This, this work was started back in 2003. I think we saw our first purple tomatoes back in 2004. And the objective of that project, where, which was a consortium project working with a number of people in other groups in Europe was simply to integrate. Increase the antioxidant capacity of tomatoes. And that was for health benefits. We were planning to do some studies, which I don't think ever got completed on the first Project that we did, but we were just, and my contribution was to say, well, I think we can make more sign-ins tomato fruit. So it was purely an academic exercise, remarkable outcome. And I think the power of an image is, is very well. It is very powerful. That's what the whole exercise taught me. No, Kevin Folta: it's very beautiful fruit with, with all of this in mind. Does it affect flavor because so [00:15:00] many flavor compounds or a number of flavor compounds anyway, come off of spurs of that Phen OID pathway. Yeah, no, Cathie Martin: actually Ayers have no taste at all. so unfortunately I can't claim any, a beneficial taste. They, because they extend the shelf life the, the tomatoes at a part at any particular. A little bit less ripe than than a regular tomato. So you, they might taste slightly under ripe or if you were to pick them very early, but they go on to develop a full flavor. Kevin Folta: Oh, very good. Well, we're speaking with Dr. Kathy Martin. She's a professor at John and center in nor England, and we're speaking about purple tomatoes and all of the buzz that they've gotten in the media. It's pretty exciting stuff. This is the talking biotech podcast by collabora and will be back in just a moment. And now we're back on the talking biotech podcast by collabrate. And we're speaking with Dr. Kathy [00:16:00] Martin. She's at the John in center in Norwich, and we're talking about purple tomatoes and it's hard to open a news. Browser in the internet without seeing pictures of these absolutely beautiful fruit. And the funny part is if you go in the Twitter, you find criticism of a purple tomato and , and I I've always been responding by saying, yes, next thing you know, they're gonna do it to eggplant . So I've seen your talks over the years, and there's so many potential. Benefits from this, but the ones that you were showing specifically by looking at rodent models gave some hints as to how they may be affecting physiology. And you mentioned a little bit about this in the beginning, but can you talk about some of the trials that have been done on observations of different physiological aspects of Ansy, rich fruits in rodents. Cathie Martin: Okay. So. What a set of experiments that's been done has been to look at the effects on [00:17:00] weight gain in mice that have fed a high fat diet. So this is a model for obesity, and it's found that if you consume. Large amounts of sinin in either in the purple tomatoes or in blood orange juice, or I think it's even been done with purple corn, which are all rich in Anin. Then the gain that occurs on a high fat diet in animals is, is minimized. So it it's reduced sometime in. At high doses, it may even be completely eliminated. So there definitely seems to be an effect on, on lipid metabolism and weight gain. But whether that's translatable to humans or not, we don't yet know all of these experiments require collaborations and I've been actively involved in some of those. We took, we've taken some of the studies forward on. P 53 knockout mice to try and identify mechanisms. And we've also looked at inflammatory bowel disease [00:18:00] in terms of something that might be very immediate In response toy in the GI tract. And I would say now looking back 15 years, really probably the impact OFCY on the composition and functioning of the gut microbiota are maybe the most important mechanism, but always remember that these are not like drugs, they're foods, they're complex matrices. They probably work in, in synergy with other components. And they probably work by multiple mechanisms. So we mustn't think of them having just one target. They may have many targets, which will be of varying degrees of importance. Kevin Folta: Sure. And then that makes sense because, you know, if it was just Ansy themselves, it would be, you know, a pill of pigments or drinking glasses as a wine. Cathie Martin: Don't worry. Those have been tried. I mean, the horrible idea of a red wine pill Kevin Folta: well, the funny you'll wash it down [00:19:00] with a glass of wine, right? Cathie Martin: I think that's a better solution personally, personally, Kevin Folta: the the funny part about this is that, well, not the funny part, the part. Really reinforces. What you're saying is when we, what we know about glucose and glycemic index in response to different, different foods that have the same amount of different sugars that can be converted to glucose, but present in different bioavailable forms like locked inside matrices, which really make them more available to different parts of the gastrointestinal tract. Yeah. Yeah. So, so that may be what we're talking about here with tomatoes too, is it's. Is that really the thinking that. That a tomato is an appropriate vehicle for maybe delivery to the place where a microbiome exists. Cathie Martin: Yes. I mean, I think, I think that we have reasonable data to suggest that the signin for the, in the case of an inflammatory bowel disease, that the anti can change the mic, the composition of the micro. Biome so that it benefits [00:20:00] those bacteria that don't produce or release allergens that cause further inflammation. However, you know, it's still, we're, it's so complicated to investigate this and you're dealing with, with yeah. Very large data sets that I can't give you a precise mechanism for any, any effect, but for sure, just look on the internet and you'll see how many people swear by a high endign in diet. Kevin Folta: No, very good. And all of this happened in a complex regulatory climate. When we, you look either in the states in England or EU they're very different in terms of how these things are regulated. And so how is it navigated? Regulation recently with U S D AIS. And really what's next for regulation before this becomes widely available. Cathie Martin: Okay. So originally, so back in 2008, when things started off, we decided that we would like to try and take this forward to [00:21:00] a product for consumers and I think that at that stage, we, we, we formed a little spin out company, but we certainly didn't have the hundreds of millions of dollars that were broadcast to be required to get U S D a approval. And so we were thinking on the lines of maybe we could do something in the us whereby we got FDA notification for a product. That that could then be sold so that it was no longer a genetically modified organism, but we wouldn't have to, we could always grow the PR the tomatoes as a field trial. So we wouldn't need U S D a deregulation to grow them outside. Okay. So that will changed when When the secure rule came in and it seemed that we would be able to get or at least apply for de deregulation, deregulatory status from U S D a AIS, because the trait was not a, a cause of concern for the environment or a pathogen. And [00:22:00] that really facilitated us being able to put in an RSR and do it without spend. The impossible amounts of money that the multinationals have to pay to get there or had to pay in the past to get their products deregulated. So that's really been the big change. We still want FDA notification. So we've had an application under. Review for two and a half years, and I'm hoping that they haven't found any major safety concerns associated with the tomatoes. And when that, when we get the final decision from them, we'll be able to go forward and Provide seeds, hopefully, firstly, for home growers. I like the idea that the most enthusiastic supporters of this are people who grow tomatoes in their home gardens and I'd really like for them to be see, see whether they like it or not. I'm not trying to force this trait on anyone, but I think it would be great to, for people to be able. I think it's beautiful. I think they make great salads and Hey, they might be good [00:23:00] for you. Kevin Folta: So, well, that's a really nice invention and, and that, I guess that was one of my questions was you spent how many years developing this thing. And now as it, essentially, I, if somebody buys the tomato, can't they just take the seeds and then grow their own, or even sell your seeds. Cathie Martin: Yeah, they can do that. You know what happens when you take your own seeds from tomatoes, you can go on growing them from self seeds, but they, the tomato plants, I mean, they, the best ones are usually hybrids and they do start to fail after a while. So I'm hoping that it wouldn't . That we have, we have the trait patented as well as you have to do. And our wholly owned us subsidiary Norfolk, healthy produce will be taking it forward. I think, first of all, for consumers, for home growers. And then if people like it, then we'll will look to develop things on a bigger scale. Yeah. It's it's very [00:24:00] much, I mean, it's a, it's a story of an academic actually take taking something all the way through to commercialization. Okay. It's not in the UK, so there's slight to bitterness to this bill but but it's really very gratifying to be, have been involved. All at all of the various stages and, and to see something that you hope could be of benefit to society. And if people don't like it, then they don't have to buy it or don't have to grow it. I'm absolutely fine with that. Choice is what I think's important. Well, Kevin Folta: we're kind of done just waiting for FDA clearance then at this point. So that's the big, that's the big hurdle at this? Cathie Martin: Yeah, I hope it's not a big hurdle. We've had many very constructive conversations with FDA, but of course they've been very busy with other matters. COVID in particular. So I perfectly understand why it's taken quite a long time to get a decision, but I hope that they'll be able to see that this is really Really [00:25:00] quite a good thing to come through. And it was a great pleasure that our RSR was the first one approved, of all of the ones, which I'm sure there's a huge backlog, but that was really nice. That as, as was number one. Kevin Folta: Well, I guess my last question is to you as a scientist, but you know, also somebody who is working, not just for the public good in terms of advancing the, the research and making good journal articles and thicker textbooks, but you wanna make. Very positive impacts. And so how do you view the issues of regulation either in the EU, in, in the UK or in the us? You've been, you've invested. How many years in this now? What is it? 17 years in this project. How frustrating is it as a researcher to wanna do the right thing for the right reason and have a regulatory climate and maybe a social climate that isn't accepting of the good work you wanna. I'm Cathie Martin: not, I'm not. So so self [00:26:00] absorbed that I think that that everyone has to, has to embrace this. I, I very much believe in choice, but I know that everyone who's ever seen the tomatoes or, or I've talked to about them has been really interested to try one. And I just like, and. I the frustration, I think you just have to be very patient. I don't want to, I want to do things right. And I do get very frustrated when, when people in Europe say it's illegal to grow, to sell GM products it's not illegal to do, and you can sell 'em in certain parts of the world and the, the advantages of biotech. Are available in certain parts of the world. And I'm hoping that the tomatoes could actually be a good example for consumers to make up their own minds about it, rather than being told that they're dangerous or that they're they're they're yeah, that they're they're or even that they are the [00:27:00] product only of multinationals and the only people that patent benefit from it. People that hold the patents. This was not my motivation at all Kevin Folta: in doing this well, we can see information about this everywhere online, right now, just through any particular news channel. But if people wanted specific information about the tomato, maybe your laboratory, where should they Cathie Martin: look? They should go to the Norfolk healthy produce website, which is called www.bigpurpletomato.com. Kevin Folta: big purple tomato.com. All right. I love it. The tomato tomato. It does. It's really funny. I have a friend who auditioned for a part and his job was to sing that old song. You know, you say tomato. I said, but he was a little younger and never knew that original song. So he went up there and said, you say tomato. I say tomato. Yeah, [00:28:00] Cathie Martin: well, I slip, I, I slip from one to the other, but I know it should be talking to you. It should be tomato. No, you, Kevin Folta: you, you do it like I do metric system and thing. I got it. You know. Well, thank you very much. Dr. Kathy Martin, thank you very much for joining me on the podcast. I really appreciate it. And let's talk about some other projects in your lab. Yeah, that would Cathie Martin: be great. I've really enjoyed it. Talking to you again, Kevin Folta: Kevin, and thank you very much for listening to the another episode of collaboratives talking biotech podcast. Write reviews on iTunes share this episode, the purple tomato is making quite a splash and it would be very exciting to be able to see it penetrate into gardens everywhere. So people could be more excited, not just about an exciting. Healthy fruit, but potentially the technology that made it. This is collaborate talking biotech podcast. And we'll talk to you again next week.