Five, four, three, two, one.

You're probably wondering why you're hearing the sound of a rocket launch in a podcast about seeds.

Well, it's because at Kew's Millennium Seed Bank in Wakehurst's wild botanic gardens, scientists are sending seeds into space to test the boundaries of life as we know it.

They're asking huge questions like what happens when a seed leaves the planet that shaped it?

How might seeds help us adapt, survive, even thrive in environments beyond our own?

And how might those answers help us adapt to our own very quickly changing world?

It may sound like science fiction, but it's happening right now.

It's taken us our life on earth, more than three billion years to send the first organisms into space.

So, I think it's good to start working on it now and not wait until the last moment.

Sending seeds into space is one way of testing the limits of life, another is far closer to home.

Cryopreservation, plunging seeds into temperatures far below anything it'd ever encounter in nature, is pushing the boundaries of what's possible here on earth.

And it's offering a lifeline for species that conventional storage can't protect.

Inside are these racks, and as the racks are very cold, so even with my gloves on I can still feel it's quite cold to hold.

And in here, I think there's space for thousands of samples inside each of these vessels.

The choices we make now, the seeds we protect today, and the science that makes their preservation possible will shape the lives of generations to come.

I'm Cate Blanchett, Kew's ambassador for Wakehurst, and this is Unearthed: The Need for Seeds.

Episode three, The Future.

If you're wondering, as I did, why with so many pressing challenges here on Earth, Wakehurst is casting their gaze out into space, I don't blame you.

Space is perhaps the harshest environment imaginable, and certainly not the easiest to reach.

But for Anne Visscher, a research fellow in the seed and stress biology team here at the MSB, putting seeds into space opens up an extraordinary spectrum of possibilities.

There are several aims for sending seeds into space, and one of them is to have them included in life support systems for human missions to Mars or the moon.

Another reason might be to store seeds as part of small banks on the moon as a second backup for use on earth, and those are called biorepositories.

And then, a third aim has been mentioned for years already is the idea of maybe perhaps terraforming Mars in the distant future.

Anne is at the heart of several remarkable space projects, two of which are destined for the International Space Station.

One will be housed on the outside, exposing 24 different species to the actual outer space conditions, and then about six species will be going to the inside of this station.

And one is even set to journey to the moon.

And then there's a project that is preparing to send seeds to the surface of the moon, first in a dry state, and then a subsequent mission to do a germination kind of experiment as well.

Space is an environment so unforgiving that just surviving is a challenge, and that is exactly what Anne and her team are putting these seeds up against.

So, the conditions that our seeds will be exposed to on the outside of the International Space Station will be vacuum and radiation, and that way we can not only look at the effect of vacuum, and radiation, and temperature in combination, which will make it harder to understand what each condition does for the seed, but we'll try to separate them out and that way we can analyze the effect of either vacuum on its own, the radiation on its own, and temperature fluctuations we'll try to mimic on the ground.

Now stay with me here, it might sound far removed, but what we learn up there has real consequences for how we safeguard seeds back down here at the MSB.

Research on earth has shown that some species actually benefit from being stored without oxygen or at even lower humidities that we're using as a standard in the bank.

Not all species, but some show increased longevity, which means that if you store them for a certain length of time and try to germinate them afterwards, you see a larger number of seeds still germinating than if you store them with oxygen or at high water contents.

So, some of our findings that might come from our space research can have an impact on how we store seeds on earth in the bank.

The team are sending seeds into the International Space Station to understand how the conditions there impact germination, and every single seed has been carefully chosen to be part of this experiment.

We've really tried to cover as much diversity as possible to be able to see if those factors make a difference, and these factors include the climate that they were collected from.

Also, the family.

We are also trying to have a range of different seed characteristics, so the size of the embryo or whether they're dormant or not, thickness of the seed coat.

By including a wide range of seeds, Anne and her team can begin to understand which species are most resilient in space, but these aren't quick experiments.

These are carefully planned long- term projects.

We've been working on this since 2014, so we're already 11 years underway.

So, it is really a practice in patience.

Hopefully it will fly in the next few years and we'll get data back within five years.

And it's always a matter of reducing your expectations and seeing the long- term picture, but taking it one step at a time.

Closer to home, Anne is studying some of the most extreme environments on earth as part of the Western Global Tree Seed Bank, a project we first heard about in episode two from Nattanit Yiamthaisong, the PhD student from Thailand.

We are trying to identify species that can survive really high temperatures during germination, over 40 degrees Celsius.

And what I'm doing there is screening over 100 different collections from the Millennium Seed Bank by looking at the areas in the world where we can see the highest average annual temperature over 27 degrees.

They're particularly interested in tree species, and what I'm trying to do is identify ones that have really high germination at 42 and a half degrees Celsius.

So, we've now screened approximately 50 collections and we've discovered several that show really good percentages of germination at that temperature.

So, we are excited to hopefully discover species that not only grow really well in the mature plant state in those hot regions, but for which we also know that they can survive really high temperatures in their really early phase of germination, when the root tip first comes out and the seedling then develops, because ultimately what we're interested in is using our collections to restore habitats and reforest regions.

The team wanted to know if the temperature of the site where each seed was collected would predict how well it germinated under high heat, but the results are surprising.

Seeds from hotter regions aren't automatically better at coping with extreme temperatures.

So, we were hoping that perhaps choosing seeds from plants that grow in the hottest areas, even within these very hot regions, we may have a higher amount of candidate species that are also tolerant during germination, but that doesn't seem to be necessarily the case.

It seems relatively random, which ones are the tolerant ones and which ones are the sensitive ones.

So, we really do need to do this screen to find out.

Anne's work depends on the seeds safely stored here at the Millennium Seed Bank, and many of these seeds come through the MSB's international partners, collecting locally, banking locally, and sending duplicates back here to Wakehurst.

But the work here isn't just about storing seeds, it's thinking about how to make collections stronger for the long term.

One way this is happening is through the new trainer certification scheme, which trains local collectors.

The idea is simple, but powerful.

Equip people globally with the skills to collect and care for seeds in their own backyards so knowledge and seeds don't stay in one place.

My name is Meg Engelhardt, and I'm the seed bank manager for the Missouri Botanical Garden.

One project that we're working on right now is we're able to pull orchid seeds from the past that are in populations that don't really exist anymore or we haven't seen them in a long time, and we're working on reintroducing those back into their native landscapes in central Missouri.

And we have woodlands and glades there that are part of the Ozarks, and so we're working on those areas specifically.

Kew was a big inspiration for our founder, so we've been peer institutions over time, and in more recent decades, that's really turned into a heavy focus on plant conservation and trying to halt this biodiversity loss.

Meg's excited to take what she's learned here at the MSB, and share that knowledge back home.

Now I get to come back here and help develop this program so that we can take it to our home countries and adapt to the people that are going to use it in our specific areas, but also the most exciting part for me is that we're all working from the same standards that have been set by the Millennium Seed Bank.

And so, when I get home I'll be able to train people who are leading their own programs or maybe just starting a small program, all the way down to practitioners who are maybe a seed collector, who then grow seeds out that people can use for restoration.

So, it will apply to professionals down to practitioners.

Meg says that the knowledge sharing is crucial, it's the key to stopping the decline of species and ecosystems.

Halting the loss of biodiversity has been at the forefront of our institution's work, and this is going to have such a strong impact in our ability to collaborate and share that knowledge, and not keep that knowledge just to the people who have access but make sure that everyone that can contribute to this really difficult problem have that knowledge and experience.

In this room we have three silver vessels, which look a bit like the vats you might see in a brewery.

Each of them contain liquid nitrogen.

So, liquid nitrogen temperature is minus 196 degrees Celsius, but on these vessels you can see the temperature gauge is around minus 170 degrees Celsius.

So, that's the temperature of the liquid nitrogen vapor in which the seeds are stored.

This is Louise Colville, senior research leader in seed biology, guiding us through one of the most futuristic looking parts of Kew's Millennium Seed Bank, the cryopreservation storage room.

Wearing thick gloves and safety goggles, she opens one of the enormous metal barrels and a cloud of swirling vapor pours out.

So, in here we have our racks which are filled with our samples, so that noise was the fan to clear the vapor because we can just see a big cloud of vapor now.

And inside are these racks, and in each rack there'll be storage boxes which contain our samples.

The racks are very cold, so even with my gloves on I can still feel it's quite cold to hold.

And in here, I think there's space for thousands of samples inside each of these vessels.

So, they contain quite a lot of our short- lived orthodox seed collections, which are duplicated from the seed bank.

Cryopreservation is reserved for seeds that don't take kindly to the usual drying and storage process.

The more tricky ones are called recalcitrant seeds, ones that we touched on briefly with seed curator, Sian McCabe, in the previous episode.

Recalcitrant seeds tend to be larger, they also contain a lot of water, and they tend to have thin seed coats as well.

So, if we think about something which probably lots of people are familiar with acorns from oak trees, also chestnuts.

So, you tend to find species which produce recalcitrant seeds in wetter environments.

So for example, trees in rainforests, and the same with species like sea grass, so they're grown in marine environments and produce recalcitrant seeds.

And different seeds have different needs.

The cryopreservation process typically has to be optimized or adapted for each species.

So, there's not one approach which works for everything, which is one of the major challenges with using cryopreservation.

So, what we do is we take out the part of the seed called the embryonic axis, and that's the part of the seed which develops into the new plant.

And because it's much smaller, it means we can then very rapidly partially dry that tissue to a point where we remove the water, which will form ice.

And then, once we've reached that point we can then very rapidly freeze it using liquid nitrogen.

The embryonic axis is that little white part you see inside a seed.

It's what I saw when we cut one open with Ted Chapman and Isabel Negri in the previous episode.

It's basically the heart of a seed.

It's the part that will grow into a new plant, which is why Louise and her team focus on preserving it so carefully, but it comes with its own challenges.

You can't just germinate these cryo- preserved seeds like you would a regular seed.

They need in vitro techniques, essentially coaxing the seed to grow from scratch in a Petri dish.

That is very complicated, and I think one of the challenges as well is that if we can regenerate after cryo using in vitro techniques, it's then moving on from that to be able to take those plants into the nursery, because obviously they've become quite used to their nice protected conditions, and then to go out where they're exposed to further stress is a big step for them.

Louise and her team are still in the research phase, working out how different species respond to this type of preservation.

It's crucial that they get it right, because each seed is different, and some very important seeds rely on this specific method to remain viable.

Although only around 10% of the world's seed- bearing plants produce recalcitrant seeds.

In some regions such as tropical rainforests, around 50% of tree species will produce recalcitrant seeds, and most of those species will also be under greater threat of extinction.

So, I think there's a real pressure here that we should be conserving not just orthodox seeds that we can conserve quite easily, but also looking at addressing the challenges of conserving these more difficult to preserve species.

Most of our work so far has been on UK trees, and actually oaks.

So quercus robur, the English oak, is quite difficult to cryopreserve and we're not really sure why.

We think part of it is down to the chemistry of the seed.

So, as soon as we remove the embryonic acid it's starting to oxidize.

As you watch, you can see them start to brown.

So, it's at that point where the challenge starts, so we need to use antioxidants to help prevent that browning before we can then move into our cryopreservation process.

But even then, even if you have a successful protocol, survival might only be 40% after cryopreservation, and that would be considered quite good.

The team anticipate that cryo- preserved seeds will endure far longer than those in conventional seed bank storage, though the long- term data isn't in yet.

Still, this approach could offer a lifeline for plants that don't produce seeds at all.

So, cryopreservation is not just for seeds, but it's also an approach that can be used for the conservation of a much wider range of plants, mosses and ferns, seaweeds, for example.

These don't produce seeds, but they instead reproduce via spores.

Over half of the UK native species do not produce seeds.

So, by using cryopreservation we can really scale up the diversity of the British flora that we can conserve.

Cryopreservation gives us a way to protect a huge variety of plant life, and Louise's research is a prime example of the innovation happening at the MSB.

But of course, preservation and conservation aren't confined to the UK.

Around the world, MSB partners are working to safeguard their own local ecosystems.

Cutting edge science and on the- ground action go hand in hand.

My name is James Amponsah, I'm working with the Forestry Research Institute of Ghana, and specifically that institute has a national seed bank called the National Tree Seed Center.

I'm in charge of managing seed conservation, especially with forest seeds in Ghana.

So, we are expected to supervise and undertake seed collections across the country.

As a partner of Kew's Millennium Seed Bank, the Forestry Research Institute of Ghana has collaborated on joint research projects and contributed seeds to the MSB.

But back home, their National Tree Seed Center is also actively involved in restoring land across Ghana, including rehabilitating former mine sites.

Ghana is currently facing a lot of problems with small scale illegal mining, polluting water bodies and degrading our forest resources.

And so, we have been involved in selecting species and making sure that we have the right framework species for restoring these degraded forests back to their natural states.

James is part of the very first cohort to take part in the new trainer certification scheme.

And just like Meg says, he's bringing those skills back home to help others and make a real difference on the ground.

This certification program for me is taking our partnership to another level.

It's really going to help contribute to our seed bank's ability to train others.

So, I think it's very important.

This training is really beneficial for us as participant.

We have come in thinking that it's going to be more of training on the standards, but in going beyond that we are now being trained with how to deliver high quality training, how to engage with our participants, how to make our training back home more impactful.

For James and for everyone he trains back in Ghana, tapping into local knowledge is just as important as any lab experiment.

When we use local knowledge in seed conservation, it's really helpful.

Sometimes local people know best where we could find best sources for seed collection.

They may even have traditional ways of pre- treating their seeds for better germination.

And so, when you ignore that you will be losing out actually as a research scientist.

And so, local knowledge is very critical for seed conservation at all levels.

The work of the MSP is really enhancing biodiversity conservation.

With climate change and with biodiversity losses on the rise, working hard to conserve seeds is actually helping us to safeguard our plant biodiversity.

It is also a way of ensuring that seed banks across the world will get to know of improved standards to help us benefit nature and people in the end.

And this for me is great.

It's really a way of empowering us to deliver our best in terms of seed conservation across our country, and even across Africa.

Insightful words from James, and another reminder of how seed banking really is a global effort.

But back here in the labs, researchers Anne and Louise are tackling a different type of challenge, cracking the secrets of seed dormancy.

Their work centers around what makes a seed stay asleep and what wakes it up or start to germinate.

Imagine a seed in autumn.

It survives the winter lying in the soil until bursting into life and spring.

Now, sometimes that awakening depends on a nudge from the environment, a physical cue to tell it the time is right.

It can be through wetting and drying, and over time this creates small cracks.

It can also be by passage through animals, by the seeds being eaten.

It can also happen through temperature fluctuations, again, causing small morphological changes and then eventually cracks.

Or it can be a molecular reason where there are certain hormones that are really high at that time that stop other processes from happening so that the whole germination growth process doesn't start.

Temperature is a well- known trigger, for example in these temperate climates that we're living in here in the UK, so some seeds are dispersed in the autumn but they won't germinate during the winter, and it's often because of their dormancy.

And what happens is that after a certain number of cold hours that they experience, they are then ready to germinate under the spring conditions.

But with climate change altering weather patterns, many seeds aren't reaching the temperatures they need to break dormancy.

That's where Louise's team is turning to an unexpected solution.

Plasma is the fourth state of matter.

So we have solid, liquids, gases and plasma.

It's actually the most abundant state of matter in the universe.

Plasma consists of highly reactive molecules and ions.

It's produced by either heating or applying an electric charge to a gas.

So, plasma's very abundant in stars, for example.

On earth, when lightning strikes, that generates plasma.

Yeah, plasma.

It's the same stuff that makes your TV glow, only a bit more alive.

Plasma consists of these reactive molecules.

We know that these interact with the molecular pathways which control seed dormancy and germination.

We're interested in whether plasma could be used to treat seeds and break dormancy.

Tree species often belong to the long dormancy club.

Many species need months of cold before they're ready to germinate.

We were interested in whether we could use plasma treatments to accelerate the process of dormancy break, perhaps shorten the requirement for the cold treatment or maybe eliminating it altogether.

We were working with Hazel, Rowan, and Beech, so those seeds all require long periods of cold stratification to germinate.

And then we also used free shallow dormant species, which was Scots pine, downy birch, and common alder.

And so, they require just a short period of cold stratification.

The team applied two different styles of plasma treatments, the first is very direct.

The seeds are put on a conveyor belt and they're passed underneath a plasma generator, and you can see little purple lightning strikes of plasma discharges connecting with the seed.

And the second is indirect, using air and water.

So, we treated air with plasma and then exposed the seeds to that plasma treated air, and we did the same with water.

So, we plasma treated water and then soaked the seeds in that plasma treated water.

And what we found is that for three of the species, for Rowan, Hazel, and downy birch, we found that the plasma treated air was effective at breaking dormancy.

It improved the germination in combination with a cold treatment compared to not having the plasma treatment.

Now, the team didn't see this coming, and they suspect it might have something to do with how the plasma interacts with the plant's own hormones.

So what we're thinking, and we still need to work further on this, is that the plasma- treated air treatment in particular is interacting with the molecular pathways controlling dormancy.

So, dormancy is particularly controlled by the balance of two hormones, and we think that the plasma is interacting with the molecular pathways which are controlling the balance of the plant hormones to help to break dormancy.

Now, it might sound a bit like science fiction, but this treatment could have real world impact.

The reason that we started working on it is that the UK government has tree planting targets, and in order to meet those targets we need to scale up tree production in nurseries.

But one of the key barriers to that is germination.

So, dormancy represents a block to basically scaling up nursery production of trees, and the reason we chose plasma treatments is because you can treat lots of seeds at once.

Innovations like plasma treatments show just how science can tackle real world challenges, and the work being done in the cryogenic space and even in space itself all feels pretty futuristic.

But I guess 25 years ago the idea of the Millennium Seed Bank in itself was futuristic.

We heard from Roger Smith in the first episode, how the initial idea for the seed bank was seen as being a little radical or out there.

However, the ambition was also huge, to build something that would last for 30 generations, a whole other millennium.

So in that respect, the MSB is really only just getting started.

From cutting edge labs to the people protecting their ecosystems across the world, the seed bank is a reminder that the future of plant conservation is being written right now.

It's a story that is still unfolding and one that is full of passionate people, pushing boundaries of what is possible in a united mission to protect the future of our planet.

The threats that we're facing are global and they are large, and there is so much more to be done that we really need to scale our work.

There's been a lot of technological advances since we started 25 years ago, and we need to be embracing some of those and bringing them into the ways that we're working.

The work that happens in this seed bank is literally saving plants and stopping us losing them.

So, to me there can't be any better reason to get out better than that.

I love plants, they're our drugs, they're our food, they are lots of people's livelihoods, and they're under so much threat from land loss and climate change.

We need to save these seeds, we need to keep them alive, we need to turn them into plants.

I feel like it's such a privilege to be able to help a little bit towards that, and I'm really proud to work here.

Working at the Millennium Seed Bank allows me to make a more active and creative contribution to stopping biodiversity loss.

Nowhere else on earth do we have access to 40,000 wild plant species to ask questions about which species are good for restoration and reforestation, and then even beyond the earth.

The MSB is like a treasure in the future for everyone.

We all come from different cultures, different countries, but we're all striving for the same goal, whether it's conserving biodiversity, ending the extinction crisis, ensuring food security in the future, and that's what I find is very rewarding.

The MSB is the only global program of its type, and it's not just about the collections that we've acquired over the last 25 years and the partnerships we've made, but it's also about the knowledge that we've generated as well, whether it's in restoration or conservation.

We're hopeful for the future and that what we're doing is good.

I think when you work in conservation, it can sometimes be hard to feel like you're having an impact, but a seed bank, to take seed from the wild, store it, keep it safe, study it, understand it, and then reintroduce it, it's really just a tangible thing that we can do to support plant conservation, and that makes it very satisfying and meaningful to me.

When I think of the Millennium Seed Bank, I think the strength is there's so many people working together and connecting, collaborating, and that's what allows us to be so strong, even in the face of climate change and biodiversity loss.

Always talk about options for the future, and that's really what it feels like.

It's a hopeful, optimistic approach to conservation, I think.

I'm proudest of the fact that a strange ragbag of individuals, in which I include myself quite happily, should come together and do something that had global significance.

Often we think of us as humans as being part of the destruction of nature.

But here at Wakehurst we're poignantly reminded of our part, and what a responsible and exciting and positive part we can play in the regeneration of nature.

And every single person I spoke to, you can tell from their engagement in the natural world and in the collection of seeds, how positive they are about the outlook that the natural world has.

And they feel a really strong responsibility of playing their role within that, which was really inspiring to hear.

I've always known that the seed bank is an important place, and the work that goes on here is deep time and meticulous, but to be out in the field with Ted and Isabel, and watch the process from the beginning right through the process of sorting, and cleaning, and collection, and freezing, it reminds me how hopeful one can be, that the work is actually happening and that it's happening not only here in this country but around the world, and the hub of that work is Wakehurst.

And I just think everyone needs to come here, and look in the windows and see that that work is being done, because what it leaves me with is wanting to go back out and grow a beautiful garden and be thankful for what we all have, and help in our own small way outside of these grounds to help preserve and protect it.

Often we think, " Well, it's all over.

There's nothing we can do." But it starts with a seed, and often that seed is infinitesimal and then it will grow into a beautiful orchid, or a massive redwood, or a Wollemi.

Just walking through the garden you're reminded of the role that science can play in the restoration of things that are natural.

They're not antithetical, they're inextricably linked.

A huge, huge thank you to everyone who has participated in this story, and everyone I've spoken to, the scientists, seed collectors, students, and local communities whose dedication has made this series possible.

Every seed collected, every experiment tested, every partnership built is a step towards regenerating nature and protecting biodiversity for generations to come.

And you can be part of it too.

By supporting Kew's Millennium Seed Bank, you're helping protect the seeds of our planet and the future they promise.

Together, we can grow a world where nature not only survives, but thrives.

As we said at the start, life begins with seeds, and so does our best chance to save it.

I'm Cate Blanchett, Kew's ambassador for Wakehurst, and this has been Unearthed: The Need for Seeds.

Thanks for listening.