Hidden World Botany: A Blooming History

I've been fascinated by plants for my entire life.

They are nature's most innovative creation.

And yet, what is most surprising

is that almost all the plants that we grow

have been altered in some way by people.

For 10,000 years, humans have created new plant varieties for food.

We used trial and error.

Then, 150 years ago,

a new era began.

Pioneer botanists used science to breed plants,

and set out to discover how plants passed unique qualities

from one generation to the next.

Botanists began to discover how plants create their astonishing variety.

They puzzled over the colour of snapdragon petals...

and the strange patterns in wild maize.

Some gave their lives to protect valuable seeds.

And together they unlocked the secrets of plants for the benefit of us all.

The long quest to understand the world of plants

would lead botanists to develop a new tool - plant genetics.

Today, botany is at the forefront of attempts to rescue a rising world population from starvation

through the production of new and improved varieties of our staple crops.

Plants really are the most incredible living things on earth,

sometimes simple, sometimes complex, but always beautiful.

And what really blows me away is the sheer variety.

Just as you think you've seen everything,

you look at a new flower

and you see something which you've never seen before.

The variety works on so many different levels,

so you have trees, you have climbers, you have herbs,

and then within the flowers you've got the diversity of colours, the diversity of shapes,

and then you find varieties on a theme,

so you find members of the daisy family, you find different scents,

so you have a plant there that smells like it's a tin of cherry-pie filling...

and all of this variety is there to do the same thing, which is to produce more plants.

And even within a group of plants that are clearly the same species,

you get a variation of height and of colour.

The diversity's endlessly wonderful.

How does this complexity of form and function come about?

It's always fascinated me,

because variety among edible plants has huge implications.

It's the key to producing more food.

To botanists in the 19th century,

how plants generated variation was the greatest puzzle in science.

150 years ago, even the great Charles Darwin described us as

profoundly ignorant of the mechanism whereby this variety was generated.

As botanists began to unveil the mechanism behind variation,

they laid the foundations of plant genetics...

..genetics which showed botanists how plant characteristics

are passed on from one generation to the next.

It would give them the power to tamper with the laws of nature

and the means to feed the world.

And yet the story of plant genetics begins with something we see around us every day...

..a concept so familiar, it's easy to take for granted...

..inheritance.

If you look at any population of plants or animals or people,

you notice that each individual is different from the next.

Each is a unique combination of the characteristics inherited from their parents.

But how do these characteristics get passed down from generation to generation?

This is a question that has intrigued the new wave of biologists since Darwin.

The first pieces of the inheritance puzzle will be put together far away in the Czech Republic.

And the evidence is buried in an obscure scientific paper, published in 1866.

The first thing you notice about this original copy is it's not in English, it's in German.

Secondly, it's written by a monk, and thirdly...

..it's about peas.

Gregor Mendel had been growing varieties of pea plant

that had different characteristics,

like whether the peas were wrinkled or smooth, yellow or green,

whether the stems were tall or short...

Plant breeders had done that kind of thing many times before.

What was extraordinary about Mendel was he repeated the experiment again and again and again.

And, even more critically, he wrote down the numbers of each kind of plant that he got in each generation.

Mendel treats plant breeding as a science.

And he spots something very odd in the numbers he's written down.

The ratio of tall plants to short, or wrinkled to smooth,

is always the same.

Nobody had ever noticed this before.

These patterns hold vital clues to understanding inheritance.

But for 35 years, nobody in the scientific community understands its significance.

In 1884, Mendel dies and his work disappears into obscurity.

That is, until the turn of the 20th century,

when Mendel would gain his greatest champion...

..William Bateson.

Bateson's a Cambridge University zoologist.

Plants fascinate him, but he's more used to working with animals.

He wants to see if he can find the same inheritance patterns in animals

as Mendel got with his peas.

This is William Bateson's makeshift laboratory.

For years, he runs a series of experiments wherever he can,

in his own garden, even in a disused church.

This is because the authorities at Cambridge University believe his work on understanding inheritance

is incomprehensible and therefore futile.

So his funding is pitiful.

Bateson's career at Cambridge had started as manager of the college kitchens,

hardly as promising sign of future success in science.

But if you have to say one thing about Bateson, he is tenacious.

He has an unshakeable belief that he is on the verge of discovering something of huge importance.

Wherever Bateson goes, the whiff of animal droppings soon follows.

Ever since a colleague gave him a copy of Mendel's paper,

Bateson's been hooked on inheritance.

He wants to know if the patterns of inheritance Mendel got in peas

are the result of a set of universal laws across the whole of the living world.

And that includes plants.

His plan is to crossbreed all kinds of different animals

and to do the same for plants, a hugely laborious task.

Without a team of helpers and no budget to pay for one,

it will be impossible.

But Bateson sees an opportunity to tap into an underused workforce on his doorstep...

the students of Cambridge's Newnham College.

They are the perfect workforce,

fiercely intelligent, unemployed and they're all female.

They become known as Bateson's ladies.

Bateson and the ladies get cracking,

and they start by looking for patterns of inheritance in chickens.

So this is the sort of experiment they do.

They cross a black cockerel and a black hen and get a brood of chicks.

But what intrigues them, surprises them, is that not all of the chicks are black.

Some of them are white.

And the more times they repeat the experiment, the stranger it gets.

The ratio of black to white is always 3-1.

Every time.

The parents must have passed down some instruction

to cause this chick to be white and these ones to be black.

Those elusive instructions we now know as genes.

Genes are too small to be seen with the technology Bateson and his ladies had in their day.

Genetics was a different kind of science.

Bateson and his ladies used crossbreeding experiments and logic

to make sense of the three-black-to-one-white ratio in their chickens.

So, how can you get this 3-1 ratio?

Well, we know that both of the parents contain the information for black feathers

because they are both black.

But we also know that somewhere hidden inside them there is information for white feathers,

because between them they can produce a white bird.

So there must be at least two sets of information in each parent for feather colour,

one black and one white.

So Bateson tries to work out how those two pieces of information

could lead to the 3-1 ratio, and this is how he did it.

Imagine that a chick gets information for black feathers from its father

and information for black feathers from its mother.

Or it could inherit black from dad and white from mum,

or white from dad and black from mum.

Or, finally, it could get information for white feathers from both of them.

Bateson and his team observe that breeding from a pair of black chickens

always produces three black chicks for every white chick.

To explain that observation, he has to make one final logical assumption.

Bateson deduces that the information for black feathers overrides the information for white,

so in three of the chicks you get black feathers.

One...two...three.

Only when the chick gets information for white feathers from both of its parents

and no instructions for black feathers do you get a white chick.

And bingo! You have your 3-1, three black, one white ratio.

If Bateson's explanation works for chickens, what about other animals?

And why stop there?

He knows that it holds true for peas, but what about other plants?

Perhaps every living thing is governed by the same laws of inheritance.

To find out, he'll need to look beyond his chickens.

Bateson and his ladies breed pigeons, goats, guinea pigs, rabbits, mice...

Wherever they look, they find the same inheritance patterns they found with their chickens,

the same that Mendel found with his peas.

Everywhere, in every species, the patterns are confirmed.

And Bateson is blown away because he believes he has found the key

to the mechanism by which all living creatures inherit the features that make them them.

And the only way the ratios can be explained

is if those features are passed down from generation to generation

in discrete units of inheritance.

A new science is born.

Bateson gives it the name by which we now know it...

genetics.

In a matter of years, Bateson has turned from marginal eccentric

into international scientific superstar.

He has proved that the strange numbers Mendel first saw in peas

are the result of a set of universal genetic laws.

These laws explain how animal and plant characteristics

are inherited in past generations,

and the same laws can now be used to predict how they will be inherited in future generations of plants.

But in 1903, Bateson hits a problem.

There's a plant lurking at the back of his laboratory

that doesn't seem to be playing according to the rules.

It seems to defy everything Bateson has learned about genetics.

The plant is snapdragon

and the problem is the colour of its flowers.

From one generation to the next,

the inheritance of colours seems utterly unpredictable.

New colours seem to come out of nowhere.

Yellow...

crimson...

..magenta.

Bateson has to question if the laws of genetics have reached their limit with snapdragons.

So he puts one of the brightest geneticists in his female team on the case...

..Muriel Wheldale.

Wheldale has an uncommon gift for making sense of complex patterns.

And she loves snapdragons.

Wheldale sets about her task armed with state-of-the-art genetic technology...

pencil, paper and lots of patience.

Wheldale has to do crossbreeding experiments just like Mendel.

Wheldale takes the pollen from one type of flower

and crossbreeds it with another plant by dabbing the pollen on its flowers...

..and grows new plants from the seed.

Then she has to count the number of flowers of each colour that come up.

Then repeat...hundreds of times

with hundreds of plants.

It looks mind-numbing and it is mind-numbing!

And this period of genetic research was called "the bean-counting period".

The trick was to remain focused on solving the problem.

For four years Wheldale sows and grows and counts...

until finally she makes a breakthrough.

Wheldale works out that there are several genes that influence the colour of snapdragon flowers.

Every possible combination of those genes generates its own unique colour.

It's a simple secret code,

and Wheldale has cracked it.

Now she can predict the inheritance of these colours...

..just like anything else in nature.

The colours of snapdragon flowers may seem trivial and whimsical,

but they reveal something fundamental to all of life on earth.

And the truth is perhaps shocking,

that the amazing biological diversity that we see around us does not require a supernatural explanation.

It is the result of genes working together like the components of a beautiful machine.

Bateson showed that Mendel's laws of inheritance were true.

Wheldale proved that genetics could predict the inheritance of even the most complex features.

By 1913, botanists see genes as a car-assembly line.

Genes are the components of machines, ready to be assembled and exploited by crossbreeding.

Out of the First World War comes a new generation of botanists

who can see that the future of genetics will change the world.

They want to put genetics to practical use.

A 29-year-old Ukrainian called Nikolai Vavilov is lucky to be alive.

He has narrowly avoided falling to his death in the mountains of Central Asia.

As far as Vavilov's concerned,

what's at stake is well worth the risk.

He's the first botanist to understand the true potential of genetics

to revolutionise agriculture.

Nikolai Vavilov is a plant breeder.

He is just back from an expedition collecting plants with valuable attributes.

He wants to cross them to create a new generation of crops.

This is more than a passion for Vavilov.

The fate of the nation is at stake

and he believes that plant genetics can save the Soviet Union.

The Russian Revolution has left agriculture in chaos.

The new Soviet Union is unable to feed itself.

Nikolai Vavilov learned genetics in Europe.

Many evenings spent deep in discussion with William Bateson in Cambridge

have sparked Vavilov's imagination.

Vavilov's plan is to crossbreed the plants he collects

to create new combinations of characteristics,

super crops for the Soviet Union.

Vavilov thinks that he can create a revolutionary set of new crops,

assembling them using the best components,

like cars on a production line.

And the expedition from which he has just returned is the start.

Imagine being able to create a fruit tree that can fight every disease

or a super wheat that combines the yield of wheat from the plains

and the cold tolerance of wheat from the mountains.

Vavilov realises that plants with valuable properties will not all be found in Russia.

To crossbreed his new generation of crops,

Vavilov will need to combine varieties collected from right across the globe.

Little by little, he gathers the seeds of every plant he finds in a central vault.

He's the pioneer of worldwide seed banks.

A seed is a survival capsule.

It contains not only the embryonic plant, but also a food supply and a tough outer coat.

It could almost have been designed for the storage of genes.

Vavilov was a pioneer in the movement to use seeds

as a way of preserving our biological inheritance

for generations to come.

And there is now a worldwide movement of seed banks

conserving not only our varieties that we have already,

but also the wild relatives of the crops that we shall need in the future

to make plants to produce more and more food in different conditions.

Vavilov's worldwide seed bank is the first step in his bold strategy

to create super crops for the USSR.

Lenin buys into Vavilov's vision

and puts him in charge of the most influential agricultural bodies in the Soviet Union.

Vavilov is to be responsible for a new scientific approach to breeding crops.

Until now it has taken centuries to breed plants with useful features,

but, armed with the new understanding of genetics, Vavilov can work much faster.

But even by Vavilov's most optimistic estimates, the work will take years.

He was often heard to say, "Life is short. We must hurry."

He couldn't possibly have known how right he was.

By 1929, the USSR is under the control of Joseph Stalin.

Stalin doesn't understand science.

He has no patience for the likes of Vavilov.

He insists the USSR needs methods to increase crop yields that make a difference tomorrow,

not in ten years' time.

Stalin's men say genes do not exist.

Only the environment in which a plant grows up is important.

It fits Marxist ideology beautifully.

Breeding and birthright count for nothing.

Genetics, they say, is bourgeois Western propaganda,

and slowly Soviet geneticists realise that their science is a political liability.

These are dangerous times.

At the age of 45, Vavilov has invested decades in his great genetic project.

Then disaster strikes.

A series of catastrophic harvests hits the USSR.

Stalin is looking for a scapegoat.

Vavilov runs several agricultural institutions. He's the perfect target.

A summer evening in the Carpathian Mountains of Ukraine.

Vavilov collects plants.

On this occasion, though, he is not alone.

Four men disguised as local bureaucrats

have searched for him all day.

They are Stalin's secret police.

These are Nikolai Vavilov's last moments of freedom.

On 26 January 1943,

Vavilov dies on the floor of a prison cell.

The man who has devoted his life to feeding the Soviet Union

succumbs finally to, of all things, starvation,

and genetics in the Soviet Union is put back decades.

World events now threaten to wipe out Vavilov's global work to develop genetics.

The Second World War...

it's the siege of Leningrad.

12 Russian scientists who have worked with Vavilov

have been trapped in an underground vault for the last three months.

German artillery is pummelling the street outside,

yet the scientists trapped inside the vault

believe they are protecting the Soviet Union's greatest treasure.

They are guarding Vavilov's seed bank,

a vast collection of seeds from around the world,

brought together to crossbreed crops for the future of all humankind.

If the war destroys this collection, his life's work will have been in vain.

It's almost impossible to imagine what it must have been like for those scientists trapped in that basement,

because not only was there a battle raging above them with the enemy trying to kill them,

but they were faced with the horrendous dilemma that they had no food.

They were desperately hungry,

yet they were surrounded by edible seeds...

which they did not touch.

The seed bank remained intact.

And these scientists sacrificed themselves to preserve a genetic resource

that we can all benefit from in future years.

Mendel, Bateson and Wheldale first unveiled the universal laws of genetics

that govern all plant characteristics.

Vavilov tried to put those laws to use,

to combine the properties of plants from around the globe.

He thought he would trigger a revolution in agriculture.

But Vavilov was stopped before he could see his dream realised.

The global revolution in food production would fall to someone else.

One year after Vavilov's death,

an American plant breeder called Norman Borlaug

is pacing his fields in a remote research station near Chapingo in Mexico.

Borlaug is an ex-championship wrestler

who grew up during the disastrous crop failures of the Midwest Dust Bowl.

Maybe it was this that fuelled his determination to make agriculture work.

Now he is a promising young plant breeder,

specialising in making plants defend themselves against disease.

And he's brought his knowledge to Mexico.

Poor soils and fungal disease have held back farming in Mexico for generations.

Borlaug is no lab geneticist,

he's a hands-in-the-soil agriculturalist.

But the advances in plant genetics by Bateson, Vavilov and others

have given him an understanding of how to combine useful characteristics through crossbreeding.

Borlaug has managed to crossbreed different varieties of wheat

to increase disease resistance.

But his most robust variety doesn't behave quite as he expects.

Borlaug's plants grow too successfully.

The heads are beautiful, plump, full of nutrition,

but the stems are growing like crazy too,

and they're too tall to support the heavy seed heads.

So in the slightest gust of wind, they fall over.

The seeds hit the ground, they rot,

and that's a waste of time, effort and food.

The solution to Borlaug's falling wheat comes out of the Second World War.

Japan is defeated by the Allies.

American troops spread across the country.

The occupied territory is a new resource to be exploited.

Like Vavilov before them,

the Americans know that foreign lands hold new plants with unfamiliar properties.

In a corner of Northeast Japan,

American botanists stumble across a strain of wheat that seems to have adapted to the local climate.

The discovery of this strain changes Borlaug's fortunes,

and the fortunes of world food production.

The strain is later named Norin 10.

I'm guessing you haven't heard of Norin 10,

and compared to the other wheat growing around the world at the time of its discovery,

it wasn't much different, apart from the fact that it grew to half the height.

Now dwarf wheat may not sound very revolutionary,

but it was about to trigger the most seismic social change in modern times.

Norin 10 is a natural genetic aberration.

It is a mutation.

In 1953, Borlaug sees a practical application for the insights of Bateson and Vavilov,

a way to use Norin 10 to produce a new plant

with just the characteristics he needs.

Borlaug crosses his top-heavy Mexican variety

with the stumpy Japanese variety...

and creates a short plant with nutritious seed heads.

Let's see what the advantage of that was.

If this weight simulates a gust of wind,

then if we hang it on this tall plant...

Ah! Broken.

On the other hand...

..if we hang the same weight on the short plant...

..the stem doesn't break and the plant doesn't fall over.

Small change for a plant,

giant leap for mankind.

Borlaug's wheat sweeps across the world.

In 1966, he takes it to the Indian subcontinent.

Since the successful introduction of dwarf wheat,

India has not once experienced a national famine.

Borlaug's extraordinary success is given the name...

the green revolution.

The increased yields come at a cost.

Higher inputs of fertiliser and water,

some people say it's not sustainable for ever...

but it is clear that this dwarf wheat is the most important plant mutation in the history of civilisation,

because, armed with it, Norman Borlaug took 1,000 million people out of starvation.

In 1970, Borlaug was awarded the Nobel Peace Prize.

His work showed the immense impact of plant genetics on humanity's ability to produce food.

But like Bateson, Wheldale and Vavilov before him,

Borlaug relied on endless crossbreeding and observation to create his new hybrids.

And there was an even more fundamental limitation...

..Borlaug's success with dwarf wheat was down to the exploitation of a useful mutation

that had occurred by chance.

In the end, the green revolution came down to nature's lucky mistake.

Plant breeders faced one big problem.

They had to rely on nature to provide them with the raw materials,

that one-in-a-million useful mutation that they could exploit.

What if they could cut out nature

and design, engineer the plant they wanted,

one that could survive in a hostile environment or resist a disease?

This is a monumental task,

because to do it they have to control the genes.

The botanists' Holy Grail was a new generation of crops made to order.

Crop breeders needed precision control over plant genes.

A decade after the green revolution,

that control of genes remained as elusive as it had always been.

What comes to mind if I say "sweetcorn"?

Is it ranks of identical, pale, yellow seeds,

like the ones you buy at the greengrocer?

Now, this is wild corn.

And this is amazing!

This is really, really different.

This looks random.

Look at that! Completely different again.

Almost flame-coloured, looks like it's been burnt almost, it's been cooked already.

It almost looks wrong.

Every one of these is different.

This one's almost getting towards some of the seeds that we get in corn on the cob.

This one, you just would never see in the greengrocer's.

These ones, different again. I've no idea what's inside this one.

It really is worse than pass the parcel.

And there we've got... we've got purple, we've got blue,

we've got dark purple...

Now, 50 years ago, these crazy patterns in corn

set in motion a whole new way of thinking about genetics.

In 1945, tucked away in a corner of Long Island, New York,

you would have found a field of maize that at first glance looks ordinary.

This is the stomping ground of a brilliant botanist who would reveal the inner workings of genes,

and so propel plant genetics into the modern age.

Pacing up and down the rows of plants, cigarette in holder,

is a woman with the kind of biceps you only get from digging.

She trusts nobody else to look after her maize plants,

so she does all of the farm work herself.

She's not a farmer.

Her maize is not there to feed anyone.

She's a geneticist. Her name is Barbara McClintock.

McClintock is obsessed with understanding

how plants pass their characteristics down to the next generation...

..the same question that fascinated Mendel, Bateson and Wheldale.

McClintock has noticed mutations in her maize that behave in totally unexpected ways.

SHOTS RING OUT

McClintock's only employee is a human scarecrow

in the fields to shoot any birds that threaten her plants,

because she cannot afford to lose a single one.

Each is a rare, one-in-a-billion chance mutation.

She suspects that her maize is the key to something really odd going on in plants.

McClintock is captivated by one strange mutation in particular.

This pattern on the seeds.

It makes her suspect she might need to rewrite the rules of genetics.

Day after day, through the seasons,

she puts transparent bags over the female parts of the maize

to stop them being pollinated by the wrong plant.

She puts paper bags over the male parts from other plants to collect their pollen.

McClintock does this again and again on hundreds of plants.

Then, at the end of the day, when the male parts have shed their pollen,

she takes the paper bag and taps out the pollen on to the female parts of the plants she's protected.

McClintock places a wooden paddle in the ground

to remind her which plant was crossed with which.

She then writes down the information on an index card which she takes back to the lab.

On too many of the cards, she's forced to write, "Pulled up by the birds".

That guy with the gun couldn't have been a very good shot.

And that must have been heartbreaking because each one of McClintock's maize plants is a unique experiment.

Maize in the wild is normally red.

Today the sweetcorn in shops is yellow

because of crossbreeding a mutation in that gene.

But in McClintock's mutant maize, the red colour comes back.

Geneticists at the time think they understand mutations...

it all seems pretty simple.

When a gene is working as it should, it's like a light shining,

but when a mutation occurs, and the gene stops working, the light goes out.

There may be any number of explanations for this.

Maybe the filament has blown...

Or the bulb is cracked.

SMASH!

Or the wiring's faulty.

But whatever the reason, the important thing is, they believe,

the light can never go back on.

But McClintock's maize mutation is different,

because in many of her plants it seems to revert spontaneously back to normal.

A mutation reverting back to normal should be impossible,

like a broken light bulb suddenly coming back on.

So she needs to isolate the mutation,

a procedure she's done a thousand times before.

It should not be hard. But this time it's different

because the mutation seems to be in two places at the same time.

And that should be impossible.

She is baffled. And her interest in the mutation begins to become obsessional.

That winter, after thousands of crossbreeding experiments,

all that counting, McClintock must have been exhausted.

But still her mutation makes no sense to her.

If it had been me, I'd have gone over the edge.

The frustration eventually gets to McClintock.

She has a minor breakdown.

Then, one evening, after three years of work,

it all begins to make sense.

McClintock finally understands what is going on.

Like the early geneticists before her,

McClintock cannot see what is happening to the genes in her maize.

What she discovers is a feat of logic.

McClintock deduces that her mutation can be turned on and off,

that its appearance must be controlled by some kind of switch.

Mutations that switch on and off.

McClintock showed that genes are part of a dynamic, shifting system,

and, most importantly, that genes are under the control of switches.

McClintock's vision was revolutionary.

Bateson,

Wheldale,

Vavilov,

Borlaug...

before McClintock geneticists thought that genes were passed passively from generation to generation.

McClintock blew that idea out of the water.

She saw that plants could switch their genes on or off when needed...

..a mechanism for plants to fine-tune their behaviour

to survive everything the world throws at them.

A new level on which genes work in the world of plants.

And yet, for 20 years, geneticists resisted McClintock's work as being outlandish.

The discovery of DNA structure in 1953 and proof of gene switches in 1961,

would give botanists new tools to control the gene switches McClintock revealed.

I've watched as that DNA technology has transformed plant science during my career.

Geneticists have isolated thousands of different genes.

They can turn genes on and off

and move them between organisms.

Most of us know this as genetic modification, GM.

Genetic modification is loaded with prejudice and misinformation,

so it's very easy to forget how it fits into the story of genetics and agriculture

and civilisation.

For 10,000 years, we have been creating new plants

by putting pollen where pollen should never go

and by selecting and preserving mutations.

And as a result of the efficient way that we grow our crops in large monocultures,

these plants are susceptible to pests and diseases.

Now, if we can build stronger, more efficient plants,

then they will be able to fight off those pests and diseases,

and their yield will go up.

Certainly there may be risks attached to genetically modified plants,

but it is a known risk

that people are dying of starvation because we cannot produce enough food.

And that situation is not going to improve as population grows.

So far I believe GM has failed to address mass hunger.

But that may be about to change.

A global consortium of labs has launched has launched one of the most ambitious attempts ever

to tackle world hunger.

Jane Langdale at the Plant Sciences labs in Oxford runs one of the teams.

Her aim is to revolutionise the productivity of rice.

So, Jane, why is rice important?

Rice is an incredibly important crop.

90% of the rice that is grown in the world

-is eaten by the people who grow it.

-By the farmers?

-Yes.

They use it directly for food. They don't feed it to animals, they don't use any of it for heating

or anything. They actually eat it.

Right now, you can grow a hectare of rice and you will feed 27 people.

-OK.

-By 2050, you've got to feed 43 people from that same land area,

and you've got to use less fertiliser,

there'll be less predictable rainfall and water

-and probably there'll be increasing competition to use that land for something else.

-Yeah.

So it's a big problem.

For the last 40 years, rice production has kept pace with the increase in population.

But we have reached the limit of how much can be achieved with existing farmland and fertiliser.

A radical new strategy is needed if billions are to survive.

Jane Langdale wants to change the way rice does photosynthesis.

Like all plants, it uses sunlight, carbon dioxide and water to make sugar.

But rice does this very inefficiently in hot, dry climates.

Langdale hopes to redesign rice to make it as efficient as maize.

To me, the leaves of maize and rice look pretty similar,

so how difficult can it be to make rice more like maize?

If we are to achieve our goal

of converting rice into maize-type photosynthesis,

then we've got to completely change the internal architecture of this leaf to look like this one.

We've got to completely change the biochemistry. It's not trivial.

Photosynthesis in maize depends on those cells that surround the many veins inside their leaves.

OK, so if we just focus this a little bit...

and then I can show you on the screen here,

and you can see that the veins are stained pink,

you can see that there's two large veins there and there's about 20 cells in between the two.

Whereas, if we look at the regular leaf above, you can see a major vein here,

but then you can count one, two, three, four, five veins in the same gap as there is with that one.

So this is essentially what the rice leaf looks like, and we need to make it look like this.

We need these more regular veins,

because unless that pattern is there in the leaf,

then the rice leaf will not be able to photosynthesise like maize.

Langdale's team is trying to unpick the sequence of gene switches

that allows maize to make more veins in its leaves.

The switches are flipped in the very early stages of life,

so the only way to study the process is by teasing out tiny patches of growing cells, buried in the stems.

It's delicate, skilled work.

So I'm bewildered that Jane's asked me to give it a go!

-Pull it out.

-Pull it out? OK. There we go. Right.

So we've got our young plant, so...

-Right, so if you just put it on the...

-I'm looking for something inside there?

-Inside there, yes.

-How big is it?

Ish? You know, to the nearest millimetre?

-To the nearest millimetre? It's not even close to a millimetre!

-OK!

How am I going to recognise it when I see it?

I'm going to tell you it's there.

-Now, be careful.

-Yeah.

-If you make a big cut like that...

-I'm being incredibly careful.

..you might go straight through the main shoot.

-It's very much like cutting up an onion, isn't it, for tea?

-No.

-Careful.

-I am being careful.

-Is it in there?

-Wait, stop! Stop, stop, stop!

Increase the magnification if you can.

-Is that it?

-No.

-Is it further in still?

-Believe me, I'll scream if you get to it.

Uh-huh...!

Oh!

I hate to say this, but I think you just lost it.

Oh!

-Is it that?

-Yeah.

Is that it, the middle one that I've just gone through there?

-Yeah.

-Oh, sod it!

For a single experiment, Langdale's team needs to dissect 500 tiny balls of cells

of the kind I took two hours to turn into a mush.

Each phase of this project seems to me monumental.

The first green revolution used plant-breeding techniques

that we'd been exploiting for thousands of years.

The next revolution, starting in Jane Langdale's lab and in other labs around the world,

is exploiting a deeper understanding of genetics.

And it may be a long shot,

but the target of feeding 9,000 million people has to make it worthwhile.

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