New Technology for Looking Inside Plant Cell Walls

The Science

The structure of plant cell walls determines how easy or hard it will be to deconstruct plant feedstocks to produce biofuels. Plant cell walls contain the cellulose that is converted to fuels but the cellulose is surrounded by a tough lignin matrix that limits accessibility of the cellulose. Michael Thelen at the Lawrence Livermore National Laboratory, together with researchers from Lawrence Berkeley National Lab and the National Renewable Energy Laboratory, have combined fluorescence microscopy, synchrotron radiation based Fourier transform infrared spectromicroscopy and atomic force microscopy to study the fine-scale organization and chemical composition of plant cell walls. Using the Zinnia as a model plant because of its ease of growth in liquid cultures, the team observed the formation of the tube-like xylem cells that carry water from roots to leaves and that also contain the bulk of the plant’s cellulose and lignin. Their results suggest that these combined imaging techniques can be used to see critical changes in cell wall structure that occur during enzymatic and microbial degradation as part of biofuel production potentially leading to the design of more efficient and cost effective deconstruction strategies.


The chemical and structural organization of the plant cell wall was examined in Zinnia elegans tracheary elements (TEs), which specialize by developing prominent secondary wall thickenings underlying the primary wall during xylogenesis in vitro. Three imaging platforms were used in conjunction with chemical extraction of wall components to investigate the composition and structure of single Zinnia TEs. Using fluorescence microscopy with a green fluorescent protein-tagged Clostridium thermocellum family 3 carbohydrate-binding module specific for crystalline cellulose, researchers found that cellulose accessibility and binding in TEs increased significantly following an acidified chlorite treatment.


C. I. Lacayo, A. J. Malkin, H.-Y. N. Holman, L. Chen, S.-Y. Ding, M. S. Hwang, and M. P. Thelen. 2010. “Imaging Cell Wall Architecture in Single Zinnia elegans Tracheary Elements,” Plant Physiology 154(1). DOI:10.1104/pp.110.155242.