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Tension wood study helps tailors bioenergy feedstock

Poplar stems (left) respond to bending stress by producing tension wood. Electron micrographs from a comprehensive BESC study reveal how tension wood (bottom right) develops a secondary cell wall layer, in contrast to normal wood (top right). (Image courtesy of ORNL)

Poplar stems (left) respond to bending stress by producing tension wood. Electron micrographs from a comprehensive BESC study reveal how tension wood (bottom right) develops a secondary cell wall layer, in contrast to normal wood (top right). (Image courtesy of ORNL)

When the DOE JGI published the poplar genome sequence analysis in 2006, it bolstered several research efforts to fully develop that tree’s potential as a candidate bioenergy feedstock.

In a report published online October 4, 2011 in Energy & Environmental Science, DOE JGI’s Gerald Tuskan at Oak Ridge National Laboratory, the project lead on the poplar genome project, and colleagues at the BioEnergy Science Center at ORNL turned their attention on a characteristic of poplar trees that could be useful for increasing available sugars and ultimately, biofuels yield from trees.

To fully take advantage of the genomic information and target the genes associated with improving poplar’s potential as a bioenergy feedstock, the team wrote in their paper, researchers need to link phenotypic and genotypic data to the lignocellulosic challenges presented in converting poplar biomass to sugars for biofuels production.
In this particular study, they focused on tension wood, a natural response to stress from bending over in which cells are composed of 90 percent cellulose, twice as much as what is normally seen. The tension wood also has lower levels of lignin and higher levels of xylem and secondary cell wall material, all of which, the researchers wrote, “contribute to desirable characteristics of feedstock materials for bioethanol production. Understanding the underlying phenotypic, biochemical and morphological properties of model biomass such as Populus TW are central to informing the design of suitably tailored feedstocks.”