Morphogenesis of hierarchically patterned diatom biosilica: theory and experiment

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The intricate silica patterns of diatom cell walls have fascinated biologists for their genetically encoded variability and structural intricacy, engineers for their application potential, and natural scientists and laymen alike for their beauty. Yet, we do not understand the physical and chemical principles that guide the self-organized formation of biosilica patterns with regularly spaced ribs and nano-pores, nor are structures of similar complexity accessible through material synthesis today. We aim to reveal general principles of biosilica pattern formation across centric diatom species. To achieve this, we propose a combination of physics-guided mathematical modeling and targeted genetic perturbation experiments to mechanistically understand how hierarchical biosilica patterns form inside a growing compartment. This project has become possible through recent advances in experimental analysis of diatom silica morphogenesis. It builds on an established collaboration between the Kröger and Friedrich groups resulting in a model for the formation of branched rib patterns in a key diatom species. We aim for an integrated model in the form of a phase-separating reaction-diffusion system in a growing two-dimensional domain that quantitatively accounts for (i) branched rib patterns, (ii) transverse connections between ribs, and (iii) regularly positioned pores, where interpretable changes of model parameters account for different silica valve patterns in three prototypical diatom species with radial symmetry. Using diatoms as model system, we will advance a general understanding how the genetically-encoded organic machineries of living cells sculpture inorganic minerals.