Plant biologists have long tried to come up with a method for making trees produce large amounts of easily extractable biomass for making renewable products such as biofuels and "green" chemicals. Indeed, international conferences such as Lignin 2014 have seen scores or well-respected scientists—biologists and chemists alike—brood the reasons why successful attempts to increase biomass production have led to the making of sample plants whose stems and branches sag in sad poses or to increased difficulty at the steps of extracting and separating the main components of wood: cellulose, hemicellulose and lignin.
Whereas most of these attempts were aimed at trying to increase the production of biomass within the plant cell, a team of scientists based in Sweden and the UK came up with the idea to try to lay bare the processes responsible for the organisation of the cells in the plant's secondary cell wall. Thus the focus is no longer on maximising biomass production, but rather on finding out the exact way in which a plant goes about building its cell walls from within and who is responsible for doing what in that process. The researchers found as many as 605 proteins hard at work, performing specific and mostly non-overlapping tasks to control aspects of the cell wall's organisation such as its thickness, homogeneity, cortical position and patterns.
"The discovery is fundamental as it unravels the mechanism enabling wood cells to deposit their secondary cell wall—[in terms of] thickness, homogeneity, cortical positioning and patterning—which gives wood its properties for any future use", according to the associate professor affiliated with Umeå University in Sweden. He is well on the way to becoming an authority on the subject of secondary cell wall deposition in plants. Just two years ago this team made a splash in the scientific literature with evidence to show that the part of the biomass which is lignin can only form once specific cells in the plant's vascular system die.
Pesquet said the new discoveries detailed in the article 'Proteomic analysis of microtubule interacting proteins over the course of xylem tracheary element formation in Arabidopsis' were essential knowledge for the research community to build on and which should give new hope to biorefinery industry.
"Since we know the specific organisation of biomass allocation in the cell, future work can focus on tailor-making trees and altering the biomass in some places.
"The importance is not to make [the tree produce] more biomass, the cell will do this. What is important to understand is how the biomass is organised in the cell... We found 605 proteins that are targeted to this process. This was possible thanks to the use of quantitative proteomics using a nitrogen protocol".
Clearly, the identification of process-specific proteins and the discovery that these have distinct and often non-overlapping functions are key in this study, because they open up the possibility to modify specific genes in trees and other plants with a certain outcome in mind.
Analytical research methods used in this study include transcriptomics, quantitative proteomics using nitrogen isotope metabolic labelling, in silico interactomics and genetic modulation of key proteins affecting the organisation of wood cells in biomass. The microscopy techniques used were real-time live cell imaging and confocal 3D reconstructions.
TPC2015-00314-LSBR2_Supplemental_Movie_3 from Bio4Energy on Vimeo. Animated
illustration of what the scientists saw thanks to their analytical instruments. Video by
courtesy of The Plant Cell/American Society of Plant Biologists.
The team behind the article 'Proteomic analysis of microtubule interacting proteins over the course of xylem tracheary element formation in Arabidopsis', was made up by the following researchers:
Bio4Energy/Umeå Plant Science Centre, Umeå University, Sweden
John Innes Centre, Norwich, UK
Umeå University and Bio4Energy issued a press release in Swedish and in English, respectively, to press and media.