Science Friday - ‘Time Capsule’ Rocks And Earth’s Mantle | Genetically Engineering Stronger Wood

Episode Date: September 12, 2024

Samples of 2.5 billion-year-old mantle rocks found at spreading ocean ridges could put bounds on models of how the planet formed. And, researchers decreased the amount of lignin in poplar tree wood, making it stronger and slower to deteriorate.‘Time Capsule’ Rocks Provide Clues About Earth’s MantleIf you’re looking to really learn about the history of our planet, look to geology. Ancient rocks can provide a time capsule of the conditions in which they formed. But even the geologic record has its limits—rocks and minerals get weathered, buried, heated, melted, and recycled over time—so geologists need to search out rare super-old geologic holdouts to tell about the earliest times.Writing in the journal Nature in July, researchers described what they can learn about the chemical history of Earth’s mantle, the geologic layer beneath the planet’s crust, from studying 2.5 billion-year-old rocks collected at spreading ocean ridges. They found that these unusual mantle rocks didn’t necessarily have to have been formed in a world with less available oxygen, but could have been produced just by the mantle layer being hotter long ago.Dr. Elizabeth Cottrell, chair of the Department of Mineral Sciences at the Smithsonian’s National Museum of Natural History, joins Ira to talk about the research and why a collection of old rocks is an important part of international scientific infrastructure.Genetically Engineering Stronger Poplar Tree WoodTrees play a big role in the fight against climate change: They can soak up carbon dioxide from the air and store it for centuries in the form of biomass. But it turns out that trees could be doing even more.In 2023, Science Friday covered how the company Living Carbon had genetically engineered poplar trees to have a more efficient photosynthesis process. This allowed the trees to grow twice as fast and store 30% more carbon biomass than regular poplars, making them ideal for the carbon credit market.Recently, researchers at the University of Maryland also experimented with genetically modifying poplar trees. But this time, they had a different goal in mind. They modified the tree to reduce the amount of lignin in its wood. This made the wood stronger without the need for harsh chemical processing. It also slowed the deterioration rate of the wood, which allows it to store carbon for longer periods.To explain more about this “super wood,” SciFri guest host Sophie Bushwick is joined by the lead plant geneticist on the study, Dr. Yiping Qi, associate professor at Department of Plant Science and Landscape Architecture at the University of Maryland.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

What if you could engineer a kind of wood that was stronger and more durable, but also could help soak up carbon from the atmosphere? We have another way to really retain the sort of fix the CO2 in the wooded material. So in this way, we can sequest more carbon over time. It's Thursday, September 12th, and you're listening to Science Friday. I'm Cyfry producer Charles Bergquist. Last year, we featured a story about a genetically engineered poplar tree that could grow twice as fast to store 30% more complex.

carbon. Now, researchers at the University of Maryland have their own advance in genetically modifying poplar trees, but they had a different goal. Instead of growing faster, they aim to make the wood stronger so it could be turned into lumber without the need for harsh chemical processing. This modification also made the wood more durable, allowing the trees to sequester carbon from the atmosphere. Sophie Bushwick takes you inside that wood project, but first, how scientists are learning about early days on Earth by looking at 2.5 billion-year-old rock. from the bottom of the sea. Joining me now is Dr. Elizabeth Cottrell,

chair of the Department of Mineral Sciences at the Smithsonian National Museum of Natural History. She's also curator of the National Rock Collection. Did you know we had one? And co-author of this study, welcome back to Science Friday. Thanks. It's my pleasure to be here. Do we have a national rock collection?

We do. We do have a national rock collection. And it's really an important part of U.S. scientific infrastructure and international scientific infrastructure. We have rocks from all over the world, and they are freely available for study to researchers around the globe. If you think about it, we often spend a lot of money to go and get rocks from exotic locations, and it makes a lot of sense to curate them and make them available for use again, rather than having to go back and we collect them.

Yeah, I know you showed me some of these great old rocks, but I don't want to get off the track here because we could easily talk about rocks, one of my favorite subjects. I want to get on the track to talk about where do you get a two and a half billion year old rock? Well, the most common locations for super old rocks are on the continents, but in this case, we think we have really old rocks that have been dredged from the sea floor. So the rocks in our study come from three different locations on the seafloor. One set of rocks was actually recovered by icebreakers under the North Pole.

No kidding. Yeah. Another set of rocks was recovered from the seafloor south of Africa between Africa and Antarctica. And another set of rocks was recovered from the seafloor in the Pacific Ocean. So we've gone to great lengths to acquire these rocks. They're all from locations on the seafloor where the Earth's crust is spreading apart and new ocean floor, new ocean crust is being created. You mentioned the difficulty of getting these rocks. Are they rare? Are there a lot of them? Well, this rock type in our study is not rare on the global scale. The mantle of our planet is about 70% of the volume of.

our planet. So by that metric, mantle rocks are not rare on the earth. But finding them at the surface is difficult, and that is rare because when the mantle melts, it creates the earth's crust. And so the crust covers up the mantle. These few settings on the planet are places where the mantle is exposed, for example, in fractures. And we can send ships out, dredge the seafloor, literally drag you know, a bucket along the seafloor and kind of go fishing for rocks. And in these rare locations, we find pieces of the mantle. Wow. And if you showed me one, what would it look like? I mean, does it look any different from an ordinary rock? Well, no, probably not. They have abundant quantities of the mineral olivine. Now, you may know the mineral olivine by the trade name Peridot,

It's August's birthstone, green mineral, and that's the dominant mineral in this rock called peridotite, peridotite, named after this olivine. But often these rocks on the seafloor, you know, they've rusted somewhat, and so they can appear weathered in orangey. They also have the minerals orthopyrgyxene and spinel, which may or may not be minerals that you've heard of commonly. And then deeper in the earth's mantle, the mineral garnet replaces this mineral spinel. But peridotites with garnet are not recovered from the seafloor. So our rocks that we studied here are the minerals olivine, orthopyrxene, and spinel. So these mantle rocks are unusual, but are these the oldest rocks around?

No, by no means these are not likely to be the oldest. rocks around, but they are likely to be older than the average mantle that circulates and is recovered from these seafloor locations. And how do you date the rocks? How do you know just how old they are? We don't know how old these rocks are. What I can tell you about these rocks is that they have melted to extreme extents. If you think of these, these rocks are the residues of creating the earth's crust. In other words, these rocks have melted and given up their melt to create the earth's crust. And so if you think of us ringing out a sponge and the water coming out, these rocks in our study have been squaws dry. The melt has been extracted.

And it's been extracted to a large extent, an unusual extent, that we infer happened under really hot conditions deep in the earth. And those kind of temperatures are not really available today, but would have been available in the Archeon billions of years ago when the Earth was hotter. So what do you seek to learn from them? What can they tell you? our team is interested in the history of oxygen in the deep earth. We are interested to understand how our planet evolves, how new crust forms, and the role of oxygen in that process. It's all part of this big story about how Earth has formed, how it's evolved, and how our planet has become habitable. One of the interesting things about the history of oxygen in the mantle is that the oxygen availability in these rocks governs things as basic as the gases that are emitted from volcanoes, the gases that would have formed Earth's earliest atmosphere.

And so when we're thinking about planets and planetary formation and signatures of habitability, it all comes back to. the rocks that make up the interiors of planets. So these rocks, as you say, they melted at a very high temperature, but without doing the equivalent of rusting? Yeah, you are bringing up a prime example of oxidation in our everyday lives. Corrosion is an example of iron oxidation. And when metal russes, an iron atom loses in an electron, this is oxidation.

You're exactly right. So that is exactly what we're looking at in these samples. That's what we're analyzing. We're looking at the amounts of oxidized iron and reduced iron to tell us something about how active oxygen was in the mantle in these ancient times. So it tells us something about how the composition of the Earth's mantle has evolved, or in this case, we're suggesting that it hasn't evolved so much and that this chemical signature, is generated simply by the natural process of the planet cooling rather than by some other process that could have changed its chemical composition. It's sort of the Earth just doesn't make rocks like it used to. That is the best way to say it. How do you go further with this? Do you have to find more rocks, or is this a thing you can follow up on in the lab?

This is something that we can follow up both by analyzing more rocks. It's always good in any science to reproduce results and test additional hypotheses. But we are definitely following up with laboratory work. In our lab, we can create conditions such as are found in the deep earth. We can create very high pressures and very high temperatures. And we can melt rocks in the lab and study the, the chemistry of that melting process under different conditions of oxygen availability, under different temperature conditions, and under different pressures. So my group is particularly interested in following up on laboratory experiments to help us understand the rock record. What would be the take-home lesson that you learned from the discovery of these rare old rocks? The take-home message of our study is that we may be able to produce these really unusual

chemistries in this type of rock by changing the temperature and pressure at which they melted and not by changing the bulk composition of the rock. And that is really important because it really helps us as Earth scientists to, eliminate or to support entire classes of models about how the planet formed and has evolved for these billions of years and how the atmosphere has evolved and how the interior of the planet has linked to planetary habitability. Well, Dr. Cottrell, I could talk about rocks forever because I love talking about them and looking at them. So I want to thank you for taking time to be with us today. Thanks. It was so much fun. I'm thrilled to be here. Dr. Elizabeth Cottrell, chair of the

Department of Mineral Sciences at the famous Smithsonian's National Museum of Natural History. She's also curator of the National Rock Collection. We know trees play a big role in the fight against climate change. They soak up carbon dioxide from the air and store it for centuries in the form of biomass. But it turns out that trees could be doing even more. Last year, Science Friday covered how the company Living Carbon had genetically engineered poplar trees to grow twice as fast and store 30% more carbon than regular poplars. Now, researchers at the University of Maryland have also dabbled in genetically modifying poplar trees, but they have a different goal. They're aiming to make the woods stronger so it can be turned into lumber without the need for harsh chemical processing.

This modification also helps the wood last longer without deteriorating, which lets the trees store carbon for longer periods of time. Joining me to talk about this superwood is the lead plant geneticist of the study, Dr. Iping Chi, Associate Professor at the Department of Plant Science and Landscape Architecture at the University of Maryland. Welcome to Science Friday. Thank you so much for joining us. Nice to meet here, Sophie.

Let's get into this superwood. What is it, and how do you genetically engineer trees to produce it? Sure, yeah, I just want to give you a little background information. So a few years back, my colleague Dr. Liang Binkhu, in the engineering college, he actually published a paper in nature reporting engineering of super strong wood using chemical treatment. So after chatting with him, so we had to be inspired to seek another more sustainable way, which is rather than using chemical to remove certain ligning in the wood material,

we were genetically engineered the wood. by editing one gene called a 401 in this case. Just one gene? Yeah, just one gene, because this gene is a kind of work, is coding for enzyme involving ligating biosynthesis pathway. So if we knock on this gene, we're going to affect this pathway. The plant, the tree, will make less negonine. So this is our hypothesis.

So my lab is really good at genetic engineering and genome editing. So we just apply a technique called a base editing to not call this 4C1 gene specifically. In this case, it's poplar tree. So where we found that we can reduce about 13% of ligning content in poplar tree. And this is a level typically, Dr. Hu's lab, going to be using chemical to remove this amount of lignin for engineering super strong wood. And then we went ahead to do the similar processing yet without doing any chemical treatment.

So wait, what is lignin? What does it normally do and why it is taking it out make the wood better? That's a very good question. So lignine actually is essentially one major part of the secondary cell wall material from our wood, any wood material, any trees. You will find them there. Different tree variety have different content, and they have actually pretty important role for structure and also filling the open space in the cell wall.

But because different trees have different level ligning, because many processing of wood requires removal of ligning, so it's kind of necessary to do ligament removal using chemicals when we're processing wood such as engineering, super strong wood. And when you take it out, you've found that the wood is stronger, but also you've mentioned that it stores extra carbon dioxide. How does that work? Why is the super wood better at trapping CO2? So the idea behind this carbon secretion is many of the, you know, we grow forest, we grow lumbers, and we use the lumbar to do building construction and other materials. And the super strong wood is a primizing sort of material because it further engineered from natural

wood. Because of that, this wood is very strong and can resist into a lot of deterioration environment can hence last much longer. So if we can have wood engineered stay there for much longer time without being sort of like degraded, releasing CO2 back to the atmosphere. So in this case, we consider we have another way to really retain the sort of fixed CO2 in the wood material. So in this way, can sequest more carbon over time. And you've done this genetic modification in Poplar trees. Why did you choose to work with this kind of tree? Yeah, very good question.

So Poplar tree is one of the major sort of research target or plant species we are using to understand a tree and also material. It is really, it can grow pretty well in the temperate environment in northern atmosphere, not necessarily in the very hot environment where pine can thrive. So the real reason are using Poplar is really for us to sort of use it as, a motor tree system because it is amenable for genetic transformation. So that scientists like me, our lab can really work on them to modify genes rapidly to create the genome, engineer the trees and assess their property.

So with engineer like Dr. Hu. So this is really a motor system. So once we have found something is working in this case, we can expand other tree species. And what do you see as the ultimate goal of this line of research? First of all, this research we've just published is really just a, prove concept. And ultimately, what we want to do, we would actually expand this approach, this concept, to the tree, which are more relevant for us to use building material, like pines, for example. So if we can do that, and then I think that will be economically, there will be

a lot of potential there. So this is really one major step for us to, you know, have this result. And we're excited to really explore in other trees by applying similar technologies. Thank you so much for joining us. You're welcome. That was Dr. E. Ping Chi, Associate Professor at the Department of Plant Science and Landscape Architecture at the University of Maryland. And that's it for today. Lots of folks help make the show this week, including Dee Petersmith, Phyllisomez, Emma Gomez, Jackie Hirschfeld. And many more. Tomorrow, SciFri's Kathleen Davis takes us on a tour of some of the top stories from the Week in Science. And a look at the world's first whole eye transplant. But until then, I'm SciFri producer Charles Berkwist. Thanks for listening.