Editorial

The EU COST Action E20 focuses on Wood Fibre Cell Wall Structure. The purpose of the Action, and others like it, is to bring together scientists from different member states of the European Union with the aim of establishing collaborative research among them. In this particular Action, plant scientists from 17 European countries meet once or twice a year for a workshop centred on a particular theme. A workshop was held in Uppsala in 2001 in which the theme was “Interactions between Cell Wall Components”. Five of the presentations made at this workshop, covering a range of topics have been prepared and are published in this issue of Plant Biology.

Dr. Claudia Grünwald and collaborators describe their investigations into “The Cytochemistry in Cell Wall Formation in Poplar Trees” (Grünwald et al., page 13). This paper was one of the outcomes of the so-called “Short Term Scientific Mission” initiative, in which the COST Action provides funding for a scientist from one member state to receive training in a laboratory in another member state. Dr. Grunwald (University of Hamburg) received training in the laboratory of Dr. Katia Ruel (CERMAV, Grenoble) in the application of immuno-cytochemistry techniques to lignin components.

The second contribution on the “Inter-relation between Lignin Deposition and Polysaccharide Matrices during Assembly of Plant Cell Walls” comes from this latter group (Ruel et al., page 2). In this paper the modifications caused by genetic down-regulation of the enzyme cinnamoyl-CoA-reductase from the monolignol biosynthetic pathway were investigated at the ultrastructural level in several species. This down-regulation led to a depletion of non-condensed forms of lignin, which coincided with a transitory disorganisation of the textures of cellulose microfibrils.

Ulla Vainio and collaborators (University of Helsinki and the Finnish Forest Research Institute) discuss the variation of microfibril angle (MFA) between four provenances of Sitka spruce, measured by X-ray diffraction and small angle X-ray scattering (Vainio et al., page 27). MFA decreases from the pith towards the bark, which is a general trend in many tree species. However, large differences were found between different provenances. They also measured the thickness of the cellulose crystallites, which appeared to be 3.0 nm, the value generally found in flowering plants.

Dr. Ingo Burgert from the group of Dr. Stefanie Tschegg (University of Agricultural Sciences, Vienna) (page 9) compared two fibre isolation techniques, chemical and mechanical, and tested strength and stiffness of different types of wood with different microfibril angles. The influence of microfibril angle on strength and stiffness was much better preserved after mechanical isolation.

Microfibril angle was also the topic of a theoretical contribution of Dr. Anne Mie Emons and coworkers (page 22). In this paper the authors further elaborate their geometrical model for cell wall architecture formation. This model relates the microfibril angle to the density of active cellulose synthases in the plasma membrane of cellulose depositing plant cells, the distance between individual microfibrils within a lamella and the cell geometry. The model predicts wall texture when one of these parameters, for instance the distance between individual microfibrils, is altered by modification of genes responsible for the production of proteins involved in formation of cell wall matrix constituents. In the present paper the authors show that their model is not only able to produce helicoidal, but also axial, helical and crossed polylamellate wall textures. These different textures have all their own mechanical properties important for the use of plant products for industry.

The five selected contributions provide an excellent illustration of how an industrially important topic can be attacked with a range of fundamental approaches to provide essential knowledge for crop improvement.