Can Genetic Modification Help Plants Survive Climate Change?

IRA FLATOW: This is Science Friday. I’m Ira Flatow. In India and Pakistan, temperatures topped 120 degrees Fahrenheit earlier this spring and then stayed above 100 degrees for three consecutive months. Of course, you know that Europe is currently sizzling under similar temperatures, record breaking in many countries. And as climate change continues, we’re only going to see more heatwaves like these, which is dangerous for human health, sure, but another concerning effect of deadly heat– plants, including food crops we depend on, have weaker immune systems when it’s hotter, which means more diseases wiping out harvests.

Worrisome on a warming planet, yes, but researchers are working on solutions. Research published in Nature last month offers one option, a gene-editing solution to keep crops healthy even at high temperatures. With me is Dr. Sheng Yang He, a professor of biology at Duke University, and investigator at Howard Hughes Medical Institute, and an author of this new research. Welcome to Science Friday, Dr. He.

SHENG YANG HE: Thank you very much for having me on the show.

IRA FLATOW: You’re welcome. Can you give us some plant immune systems 101 first?

SHENG YANG HE: [LAUGHS] Sure. Plants actually have a very powerful immune system. It’s actually similar to a major branch of immune system that humans and some other animals have. It’s called innate immunity. What it is that plants have these immune receptors that can recognize all sorts of pathogens and insects, and once that recognition occurs, plants will produce defense hormones, including a hormone that, in this study, we focused on quite a bit, salicylic acid.

And so this hormone basically amplifies other cellular immune responses to make plants resistant to pathogen and insects. Yeah, so plants don’t have the antibody system that we have, but still, plants have existed on Earth for hundreds of millions of years so much longer than humans and many animals. So I think the plant immune system’s very powerful against diseases.

IRA FLATOW: That immune response sounded a lot like aspirin.

SHENG YANG HE: Yeah, yeah, salicylic acid is actually very close to that compound, aspirin. In fact, aspirin was invented based on a salicylic. Old days humans chewed the willow bark that contains a lot of salicylic acid. That’s where the aspirin was initially discovered. And so we take aspirin, yeah, for a lot of human conditions, but plants actually make their own medicine.

IRA FLATOW: So when it gets hotter, do they produce more of this? Or do they not and just wilt or get sick?

SHENG YANG HE: So actually, it turns out when it’s hot, the plants that used to the cool weather condition like Europe, part of Asia, North America. A lot of vegetables are– obviously, they actually don’t like hot temperature either, so they produce less salicylic acid. And because of that, the whole plant immune system is kind of suppressed, and so they are more prone to pathogens and insect attack.

IRA FLATOW: So are there any particular kinds of diseases that might be most damaging?

SHENG YANG HE: Yeah, so salicylic acid control plant immune response to a large group of pathogens we call biotrophic, these pathogens like living cell. Some insects also are like living cells. So salicylic acid is really important for plant defense against these type of pathogenic aphids, for instance. And so these diseases are particularly controlled by salicylic acid.

IRA FLATOW: And what role does it play in temperature response?

SHENG YANG HE: It controls immune response. It doesn’t control the growth or flowering, and these are other issues that plant scientists are working very hard, try to produce a new generation of so-called heat-tolerant crops that allow plants to grow in warmer regions or hot weather. In fact, the breeders normally focus on growth and fruits and flowering, but our research suggests that we should now pay attention to the plant immune system as well because it’s very susceptible to warm temperature. You can grow all the plants you want to. If the immune system not strong or resilient, we’re not going to get to the expected yield.

IRA FLATOW: So could we expect that climate change and global warming, as it heats up, is going to wipe out some food crops?

SHENG YANG HE: That is a prediction, actually. We’re very concerned about that. One reason is that a lot of crop plants don’t flower at the time they supposed to flower. You probably noticed that the spring very warm. A lot of fruit trees fell out really fast. And so then a freezing temperature comes in to kill other flowers. A lot of time you don’t even have a fruit that year. And the same can happen for food crops and vegetables, especially cool weather crops will have a series of challenges going forward.

IRA FLATOW: And you’ve been working on genes, testing different genes, for a potential solution using gene editing that lets plants keep making the chemicals they need to fight disease. Tell us about that.

SHENG YANG HE: Yeah, so that’s the main focus of the work. So once we find that salicylic acid is not produced enough, we want to know why, why it’s not producing enough. After many, many failed experiments, as you know science is like that, we eventually realized that, actually, a gene we call CB60g, but– it’s not important. This gene actually functions as like immune’s master switch. At one temperature, it turns out this gene is not tuned on for some reason.

And so once we figured out that, we basically did a repair experiment, modify the part of this gene to be temperature insensitive. So now the plant is able to switch on this master immune genes and then make salicylic acid, and other defense systems allow plants to actually resist pathogen, even at warm temperature. So I think this is the one solution. Obviously, there’s additional solutions we and others are exploring to basically make plants resilient to temperature so that they won’t get sick.

IRA FLATOW: Amazing. Can you give me the range of plants that this gene might help?

SHENG YANG HE: Yeah, so we only worked on a particular plant called Arabidopsis. Now, not that important to remember the name, but this is like lab rats for plant research.

IRA FLATOW: That’s the old mustard plant, right?

SHENG YANG HE: Yeah, yeah, so a lot of scientists want to use this one because it’s a typical plant, obviously, has all the traits that it has. But there’s a lot of knowledge and resources available to make a discovery fast. It is also relative of vegetables we eat. So that’s what we are working on, but obviously, you want to know whether the phenomenon you discover is also occurring in crop plants.

Fortunate to us, the gene, the immune master switch that we found, is actually in all plants, so it’s pretty wide spread. And we also tested several crops like tomato, rice, rapeseed. The salicylic acid system is also compromised at warm temperature, so this is a pretty pervasive phenomenon in plants, including crop plants.

IRA FLATOW: How much of a difference did it make when were you able to turn on that master gene? How much difference does it make in the plant fighting off all its enemies?

SHENG YANG HE: Yeah, so for instance, the plant Arabidopsis will usually grow at 20, 21, 23 degree. That’s what we normally do. We increased temperature by 5 degree to 28. So normally, plants become really sick because their immune system is down. The modified plants we have able to fight as well as the normal plants would at the lower temperature.

So we haven’t tested the limit of temperature you can go. In general, we and others really want plants to have this robust temperature resilience, not only in immune response but also setting the flutes and the flower time to be more resilient to temperature differences so we can grow crops not only in one location but in all over the world. Right now, you heard about the importation, transportation, the other political issues that make the global food security an issue.

Can you imagine that we can all grow food crop anywhere we want to? And that will really dramatically improve the condition we have. So that’s what we’re aiming for as a community of plant scientists.

IRA FLATOW: Can you tweak up the system and amplify the immune system rather than just bring it back up to par? Can you strengthen it?

SHENG YANG HE: Yeah, you can do this easily. We’ve done this in the laboratory, we and others. The problem with that is, once you do that, plants actually cannot deal with that perfectly because, essentially, there’s a phenomenon called defense and growth trade off, that if you devote too much energy to one thing, the other part of your system doesn’t work very well.

So you can hike up the defense very high or all the time. Plants actually become very small, and so that’s not good. That’s not what we want. We want a lot of flutes, a lot of biomass. And so there’s a balance we need to achieve. We need to make sure that defense only up when we need it to, and we need a level of defense that just enough so that we don’t want to divert energy from other part of the plant life that it needs to cover.

IRA FLATOW: Yeah, I know because I know that herbicides work by getting the plant to grow too quickly and it kills the plant. So you don’t want to do that.

SHENG YANG HE: And there are other examples.

IRA FLATOW: Right. How should we be thinking about the role of GMOs in our food system? This is going to be a genetically modified plant. I know some people are uneasy about them. But won’t we need to consume more GMOs in our future diets if we’re going to fight climate change?

SHENG YANG HE: Yeah, so there are two answers to this. So our eventual goal is not to use GMO to this very early stage. What we want is, really, to find some alleles they are really in nature and by then introducing to the cultivar like what conventional breeding is. So the goal is not to make GMO.

However, as a scientist, I know GMO is very safe. It’s probably more safe than some of the natural food we eat. And I think public will eventually realize that GMO food is as safe as natural food. But again, this is a debate that we’re going to have for a long time, and we should allow different opinions, different choices. Again, the goal of the scientist is to find as natural approach as we can but, at the same time, to come up with more nutritious, and safe, and affordable food that we can all eat or continue to eat, even though we’re going to live in a very hot and harsher climate.

IRA FLATOW: I’m Ira Flatow. This is Science Friday from WNYC Studios. Let’s talk about the science here a bit. We talked about how temperatures impact a plant’s immune system. What about all the other impacts of the climate crisis like drought, flooding, humidity? How might the plants fare against these?

SHENG YANG HE: Yeah, yeah, what you want is to make a plant to be able to resist the high temperature, drought, and high salinity. And these are associated with climate change. We should pursue that as a community, obviously, but in reality, you don’t need to have a particular culture that resist to all kind of stress because we still grow plants, crop plants, in a regional basis. So in this region, maybe the hot temperature is the main issue. In another region, in California or something, drought is a problem.

So we need to create a library of elite cultivars that can be grown in different places. And I think that’s what we want to do. But yeah, drought, salinity are major problems.

IRA FLATOW: While you’re worrying about the health of the plants and something that you should be worrying about, what about the health of the soil in climate change and the climate crisis, the microbes, the microbiome in the soil?

SHENG YANG HE: Yeah, the temperature and drought, especially salinity, has a huge effect on microbiome, about the kind of microbiome that are going to live there and how they actually function. Microbiome is such a critical component of plant health, so affecting microbiome could indirectly affect playing health. This is the called holobiont.

Plants not really just plants itself. It’s actually living with the microbiome. And so microbiome can be a solution because, a lot of times, the microbiome can actually boost plant health and make plant more resilient to temperature and drought without actually our need to modify plant genome. So this is another non-GMO solution that we and others are looking at. So–

IRA FLATOW: That is–

SHENG YANG HE: Yeah, Yeah.

IRA FLATOW: That’s crazy. That’s terrific.

SHENG YANG HE: It is crazy. It’s very complex. And so it will take a while to figure out like a probiotic for plants, for instance. But our colleagues– my colleagues are working really hard on this.

IRA FLATOW: That’s great. We talked just a couple of weeks ago about the failures of wheat crops, both in the US and globally this year. It seems like protecting food from climate change is increasingly urgent. I’m sure you would agree. When can we expect to see more temperature-resistant crops? When will you get some of your research to market, do you think?

SHENG YANG HE: Right, so as a scientist, I don’t want to speculate too precisely because a lot of things are out of our control. But we want to, obviously, bring this thing if we are well funded to continue to work on this. Right now, the result’s in the laboratory, but we would want to take this in the field testing will take a few years. I would say within 10 years or so the technology should be ready.

And whether how many farmers are going to use it, that’s kind of another level of complexity that is not really solvable by science alone. We have to have a policy change, and we think of all of that. But yeah, so we do our best to bring the technology or the knowledge, at least, to people that this is actually feasible if we continue to invest.

But as a worldwide, we need, I would say, a global Manhattan Project, where governments are putting really a lot of funding because agriculture is going to be a huge critical issue for human survival. We’re seeing it as you said. Climate change is here already. You need like a big consortium of people really dedicated to address this Manhattan Project level of effort to solve all these problems– temperature, drought, salinity, food insecurity. I think this is the time to do it.

IRA FLATOW: Well, from your mouth to the world government’s ears, I want to thank you for taking time to be with us today.

SHENG YANG HE: Thank you so much, Ira. Nice talking to you.

IRA FLATOW: Dr. Sheng Yang He, professor of biology at Duke University and investigator at Howard Hughes Medical Institute, and a special thanks to Mackenzie White, our AAAS fellow this summer who produced this interview.

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