A three-dimensional perspective on multiple biomineralization in
This work presents new findings about the spatial arrangement of up to
three biominerals in plant trichomes. Many plants develop hard,
mineralized structures primarily as a defence against herbivores.
Stinging hairs and other trichomes particularly of Loasaceae show the
most complex mineralization patterns in any living organism in the form
of single-celled structures with the three biominerals calcium
phosphate, calcium carbonate, and silica. Scanning electron microscopy
with high-resolution EDX element analyses of sample surfaces and
sections provides a three-dimensional view of the extreme chemical
heterogeneity of cell walls. All three biominerals occur in two
different contexts: either as nearly pure mineral structures, e.g., on
surfaces and in hooks, or as composite materials with a higher
proportion of carbohydrates (cellulose, pectin), especially in the bulk
of the cell wall. Raman spectroscopy permits the identification of both
organic and inorganic compounds side by side. The chemical composition
of cell walls may change abruptly, or gradually across cell walls; the
cell lumen may be additionally filled with amorphous minerals.
Water-solubility of the different mineral fractions is remarkably
divergent. Overall, we here demonstrate that different mineral and
organic components permit plants to fine-tune the mechanical properties
of cells and tissues.