Hardwood tree specialists know something that the fuel tree innovators are about to catch on to.  Tension wood that forms naturally in hardwood trees in response to bending stress is known to possess unique features that render it desirable as a bioenergy feedstock.

So taking the hint, researchers at the Oak Ridge National Laboratory’s BioEnergy Science Center (BESC) have undertaken to lead a first-of-its-kind study of the naturally occurring phenomenon in trees to spur the development of more efficient bioenergy crops.

The individual elements of tension wood have been studied previously, but now the BESC team is the first to use a comprehensive suite of techniques to systematically characterize tension wood and link the wood’s properties to sugar release.  The idea is produce more sugars for producing alcohols productively.

Oak Ridge National Laboratory’s Udaya Kalluri, a co-author on the study explained saying, “There has been no integrated study of tension stress response that relates the molecular and biochemical properties of the wood to the amount of sugar that is released.”

The BESC team is learning tension wood properties include an increased number of woody cells, thicker cell walls, more crystalline forms of cellulose and lower lignin levels, all of which are desired in an biofuel crop.  The work and the preliminary results have been published in Energy & Environmental Science.

Poplar Left Tension Wood Bottom Right Normal Wood Top Right. Click image for more info.

Kalluri continues, “Tension wood in poplar trees has a special type of cell wall that is of interest because it is composed of more than 90 percent cellulose, whereas wood is normally composed of 40 to 55 percent cellulose. If you increase the cellulose in your feedstock material, then you can potentially extract more sugars as the quality of the wood has changed. Our study confirms this phenomenon.”

Another benefit is the study’s cohesive approach also provides a new perspective on the natural plant barriers that prevent the release of sugars necessary for biofuel production, a trait scientists term as recalcitrance.

Co-author Arthur Ragauskas of Georgia Institute of Technology explains, “Recalcitrance of plants is ultimately a reflection of a series of integrated plant cell walls, components, structures and how they are put together. This paper illustrates that you need to use an holistic, integrated approach to study the totality of recalcitrance.”

The current study is an early step.  Using the current study as a model, the research team is extending their investigation of tension wood down to the molecular level and hope to eventually unearth the genetic basis behind its desirable physical features. Although today tension wood itself is not considered to be a viable feedstock option, insight gleaned from studying its unique physical and molecular characteristics could be used to design and select more suitably tailored bioenergy crops.

BESC director Paul Gilna said, “This study exemplifies how the integrated model of BESC can bring together such unique research expertise. The experimental design in itself is reflective of the multidisciplinary nature of a DOE Bioenergy Research Center.”

The research team spans three institutions including Georgia Institute of Technology with Marcus Foston, Chris Hubbell, Reichel Sameul, Seokwon Jung and Hu Fan; the National Renewable Energy Laboratory with Robert Sykes, Shi-You Ding, Yining Zeng, Erica Gjersing and Mark Davis, and ORNL’s own Sara Jawdy and Gerald Tuskan.

The study abstract shows the main point behind this step in the research was the recalcitrance issue that was upstaged by the increase in the sugar content.  One can credit the designers of the research with encompassing enough ground to find the new gem in the wide area comprehensive study design.

Improving the productivity of wood for fuel use is an excellent goal in itself, but the tension wood properties could have major implications across several industries where wood strength has importance.  Construction materials come to mind, stronger woods could affect the amount of wood needed – an attribute that’s shared with the fuel use of wood.  Better understanding wood can only make many things better, lower cost and more efficient. This is research effort well spent.


1 Comment so far

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