Simulated Self-assembly of Spore Exines

Abstract

The spores and pollen of higher plants have enormous value in taxonomic studies by contributing to our understanding of past and present biodiversity, and of environmental change. The critical features used in species identification are wall structure and surface pattern. However, ultrastructural and histo-developmental studies of spore and pollen walls have, so far, provided limited explanation of wall construction and surface pattern formation. The consistency of pattern form within any species suggests a high degree of genetic regulation, and yet few templates or other mechanisms of control have been demonstrated. Our experiments show that all layers and organizations within the spore wall of our test plant group (lycopodiopsid megaspores) can be simulated by the flocculation of mixed colloidal systems. This leads us to a possible explanation of the mode of genetic control over pattern formation. It also provides a feasible, largely self-assembling, mechanism of construction which has the potential to reflect the diversity of structure known to exist in all spore and pollen walls.