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Genetically Modified Poplar Trees Offer Greener And Cheaper Diapers

CRISPR gene editing reduces lignin levels, paving the way for sustainable wood fiber production.

Greener and cheaper diapers could be on the way – thanks to genetically modified poplar trees.

Scientists used a gene-editing tool to breed varieties with halved levels of lignin – the major barrier to more efficient production of wood fibers.

Lead author Professor Rodolphe Barrangou, of North Carolina State University, said: “We’re using CRISPR to build a more sustainable forest.

“CRISPR systems provide the flexibility to edit more than just single genes or gene families, allowing for greater improvement to wood properties.”

Lignin is a natural component of plant cell walls, the scaffolding pivotal to gravity-defying heights ranging from stubbly grasses to sky-scraper-sized redwoods.

But it makes it hard to break down the matter so its carbon-rich building blocks can be converted into forms suitable for paper, comforters, clothes fillings – or even diapers.

A simple solution is to engineer plants with less lignin. But previous attempts to do this have often resulted in weaker plants and stunted growth-essentially putting the brakes on biomass production.

CRISPR-modified wood shows red coloration (l) with wild-type poplar wood (r). PHOTO BY CHENMIN YANG/SWNS  

Now the US team has achieved the feat by increasing the carbohydrate to lignin (C/L) ratios. They did the same with two building blocks – syringyl and guaiacyl (S/G), respectively.

They described the combined chemical characteristics as representing a fiber production ‘sweet spot.’

By the time they are potty trained, a baby could have used 4,000 to 6,000 disposable, or 20 to 30 reusable, diapers

Over the two and a half years a typical child would wear diapers, and disposables would create 550kg (1,200lb) of carbon emissions.

And reusables would create 570kg of carbon emissions. That’s because of the energy it takes to wash and dry them.

The carbon emissions associated with disposable diapers, on the other hand, are mainly down to the production of the materials used to construct them.

The researchers used computer modeling and machine learning to sort through almost 70,000 different gene-editing strategies targeting 21 important genes.

More than 99 percent focused on at least three genes. The best seven selected achieved 35 percent less lignin than wild trees, C/L and S/G ratios three times higher than wild trees – and similar growth rates.

The researchers used CRISPR gene editing, which acts like a pair of ‘molecular scissors’, to produce 174 lines of poplar trees – which possess softer wood.

After six months in a greenhouse on the university site, lignin was reduced by 50 percent in some, as well as a more than threefold increase in the C-L ratio in others.

The best results were seen in trees with four to six gene edits, although those with only three still had up to a third less lignin.

Sophisticated production mill models also suggested that reduced lignin could increase pulp yield and reduce so-called black liquor, the major byproduct, which could lead to 40 percent more sustainable fibers.

Greenhouse gas emissions would also be cut by up to a fifth if the technique is adopted on an industrial scale.

Forests represent the largest biogenic carbon sink on earth and are paramount in efforts to curb climate change.

They are pillars of our ecosystems and the bioeconomy. In North Carolina, forestry contributes over $35 billion to the local economy and supports approximately 140,000 jobs.

Co-lead author Dr. Jack Wang said: “Multiplex genome editing provides a remarkable opportunity to improve forest resilience, productivity, and utilization at a time when our natural resources are increasingly challenged by climate change and the need to produce more sustainable biomaterials using less land.”

Greenhouse tests are continuing to see how the gene-edited trees perform compared to wild poplars. It is hoped field trials will gauge whether they can handle the stresses provided by life outside a controlled environment.

First author Dr. Daniel Sulis said: “An interdisciplinary approach to tree breeding that combines genetics, computational biology, CRISPR tools, and bio-economics has profoundly expanded our knowledge of tree growth, development, and forest applications.

“This powerful approach has transformed our ability to unravel the complexity of tree genetics and deduce integrated solutions that could improve ecologically and economically important wood traits while reducing the carbon footprint of fiber production.”

Produced in association with SWNS Talker

Edited by and

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