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How Cambridge biochemist Prof Paul Dupree teamed up with his 80-year-old dad to solve plant mystery

By Kieran Cooke

Professor Paul Dupree, Cambridge University Biochemistry Dept . Picture: Keith Heppell
Professor Paul Dupree, Cambridge University Biochemistry Dept . Picture: Keith Heppell

A father and son team have unlocked the secrets of the strength in plants.

Professor Ray Dupree
Professor Ray Dupree

Cambridge biochemist Professor Paul Dupree was puzzled as to how cellulose and xylan molecules, which are 10,000 times narrower than the width of a human hair, came together to form strong cell walls in wood, straw and other plants - until his 80-year-old dad Ray agreed to help.

Analysing how things work – whether it’s to do with wind speeds on Jupiter or the life cycle of the large blue butterfly – is fundamental to all science.

While much has been learned, there is still a lot we don’t understand, with some of the great mysteries involving items we come across every day.

Cellulose and Xylan model. Clayton Rabideau, University of Cambridge
Cellulose and Xylan model. Clayton Rabideau, University of Cambridge

Professor Paul Dupree, at the Department of Biochemistry at the University of Cambridge, has been puzzling over the make-up of plants, particularly how some – such as wood or straw – grow strong, robust walls.

“Until now, it was a bit like cooking,” says Professor Dupree. “You know that if you mix this with that or add some particular spice to a dish, it just works.

“But how does that happen? What is the process behind it? We wanted to investigate how certain components of plants meld together and how, for instance, wood gains its strength and relative durability.”

The big mystery has been how key sugars in cells in some plants combine to form strong, indigestible materials.

A plant stem, with the cellulose shown in blue and the xylan in red. Image: Dr JC Mortimer
A plant stem, with the cellulose shown in blue and the xylan in red. Image: Dr JC Mortimer

In what has been a four-year programme of research, Professor Dupree has led a team which looked at the behaviour of cellulose and xylan, two of the most common large molecules – or polymers – found in the cell walls of wood, straw and many plants.

Cellulose molecules are rod-like and relatively thick. Xylan is a long, winding polymer with so-called ‘decorations’ of other sugars and molecules attached.

What was known was that these two polymers come together to form strong walls in plants. The big unknown was how this happens, given their very different structures.

“I had an idea of how this worked but I needed solid evidence to support my theory,” says Professor Dupree.

Professor Paul Dupree, Cambridge University Biochemistry Dept . Picture: Keith Heppell
Professor Paul Dupree, Cambridge University Biochemistry Dept . Picture: Keith Heppell

Analysing such structures in plants requires examination at the minutest scale: cellulose and xylan molecules are 10,000 times narrower than the width of a human hair.

This is where Professor Ray Dupree, Paul Dupree’s father, came into the picture.

Professor Ray Dupree is a specialist at the University of Warwick in solid-state nuclear magnetic resonance (SSNMR), an imaging technique based on the same physics as hospital MRI (magnetic resonance imaging) scanners but with the power to reveal structures at a far more minute, nano scale.

“One Christmas I was talking about my research with my father and asked if he could help,” said the younger Dupree.

“At first he declined, but then six months later he said he was willing to give it a try – he’s 80 and very active, and still works full-time.

“He’s interested in the structure of minerals, so, in a way, our interests coincided. I don’t know of any other father and son team involved in academic research projects such as ours.”

The Duprees, together with other members of the research team, managed to unlock a mystery which has been bothering plant scientists for decades.

“We knew the answer must be elegant and simple, and, in fact, it was,” says Professor Dupree.

“What we found was that cellulose induces xylan to untwist itself and straighten out, and the two bed into each other like a zip, or similar to joining up pieces of Lego. It was, in many ways, a Eureka moment.”

Understanding these fundamental factors in the structure of plants could lead to dramatic changes in various industries, such as in the production of biofuels and of paper.

“Breaking down the tough cellular walls of plants – whether for use as biofuels, for animal feed or shredding wood for paper production – has always been a problem,” says Professor Dupree.

“For instance, making paper is an extremely energy-intensive business involving large amounts of unpleasant chemicals. Now we have a better understanding of the interaction between cellulose and xylan, the amount of energy required in such processes could be vastly reduced.”

Professor Dupree studied at Cambridge and has been teaching and researching there since 1996.

He says that the way is now open to improve the properties of various woods and create stronger materials which would be resistant to insect infestations or rot.

Xylan and cellulose bound together can act as a form of glue in building structures. There could be a time when wooden skyscrapers are constructed.

“The research has opened up so many possibilities,” says Professor Dupree.

“It could be classified as one of the biggest breakthroughs in 10 years in this field of plant science.”

Reaching for the sky – with wood

Professor Dupree’s research could be key to a project aimed at constructing a building with a difference – an 80-storey skyscraper with more than 1,000 residential units in London, made up mainly of wood.

The project team, led by Dr Michael Ramage, director of the Centre for Natural Material Innovation in Cambridge, and including internationally established firms of architects, say building in wood has several advantages: wood is a renewable resource and, by using it, the overall weight of a building can be significantly reduced.

They say that people feel more comfortable around wood rather than steel or concrete and that the proposed building would meet all fire regulations applied to steel or concrete structures.

The idea has already been presented to London Mayor Sadiq Khan’s office.

At present, the University of British Columbia in Canada boasts the world’s tallest timber building – an 18-storey students’ residence block.

:: Kieran Cooke is a member of the Climate News Network, a team of experienced science journalists who write an exclusive science feature for the Cambridge Independent newspaper every week.


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