Smart Wood: Bio-Engineering Trees For Specific Purposes

Wood can do some marvelous things. It can be made into cross laminated timber to build skyscrapers up to 30 stories high. It can be used to make paper, insulation, biofuels, and non-petroleum based feedstocks for plastics and medicinal purposes. But not all trees can do all things equally well. Scientists at North Carolina State University have devoted the last 10 years studying the biological triggers that determine the characteristics of trees as they grow.

They have determined that there are 21 pathway genes that control the amount of lignin a tree produces. Lignin is the stuff that gives timber its strength and density — desirable characteristics for structural uses but not so desirable for making biofuels, paper, or pulp. For those applications, the lignin has to be stripped out of the wood, a process that requires high heat and harsh chemicals.

For the past decade, the researchers have been experimenting with switching individual genes on and off to determine what effect they have on growing trees. But they say they can now model the effects of switching all 21 lignin genes on or off in the lab, which will greatly reduce the amount of time needed to “design” trees that are suitable for particular purposes.

“For the first time, we can predict the outcomes of modifying multiple genes involved in lignin biosynthesis, rather than working with a single gene at a time through trial and error, which is a tedious and time-consuming process,” says Jack Wang, assistant professor in NC State’s College of Natural Resources and lead author of a paper about the research in Nature Communications.

“Having a model such as this, which allows us to say if you want this type of wood, here are the genes that you need to modify, is very beneficial, especially when you have an enormous number of possible combinations with 21 pathway genes,” Wang says. “It’s only possible through integrated analysis which allows us to look at this process at a systems level to see how genes, proteins, and other components work together to regulate lignin production.”

The model tracks 25 key wood traits. For timber, density and strength are paramount. Biofuel producers home in on genes linked to high polysaccharide levels, allowing wood to be more easily converted to biodiesel or jet fuel. Pulp and paper producers look for wood with low lignin levels or wood that is more readily hydrolyzed. High lignin woods are novel resources for the production of special value-added phenolic compounds, according to Science Daily.

“The complexity of biological pathways is such that it’s no longer sufficient to look at small-scale, independent analysis of one or two genes,” Wang says. “We should use a systems biology approach to look at entire pathway-wide or organism-wide analysis at a systems level, to understand how individual genes, proteins, and other components work together to regulate a property or a behavior.”

The research could lead to more research, such as how to produce “trees that can be paired with thermophilic bacteria for optimal conversion to biofuels and biochemicals,” Wang says. “We are also looking at this integrative analysis to generate trees specifically tailored for production of nanocellulose fibers to replace petroleum-based materials such as plastic.”

How cool is that?

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