Chiral cellulose structures in plants
We have started to look at some
larger dimension structures found in plant cell walls. As example, we have
started exploratory work on plant petioles (leaf stems). The structure of the
vascular elements (i.e., the plumbing) in leaf stems has been known for a
century or so, but to our knowledge no-one has tried to isolate the cellulosic
structure that acts as reinforcement of the vessels that the conduct the sap.
By careful physical and chemical treatments, we have isolated petiole cellulose
as long helical tightly-wound tubes that clearly reinforce the walls of the
vascular elements. An example of such a coil, after isolation and elongation,
is shown below.
Left
handed helical coil from vascular element of a rhubarb petiole. (polarized light
microscope, 530nm red waveplate, Coil diameter, ~50µm
). (D.G. Gray, unpublished result)
Coils were isolated from a range of leaf petioles, ranging from celery to maple
and ginko leaves. In all cases the coils were
left-handed. Possible reasons for the ubiquitous nature of these coiled
structures in the water transport systems of plants are under consideration.
[“Isolation and handedness of helical coiled cellulosic thickenings from plant petiole tracheary elements.” D.G. Gray, Cellulose, 21(5), 3181-3191 (2014)]