Turgor-driven plant cell growth depends on cell wall structure and mechanics. Strengthening of cell walls on the basis of an association and interaction with silicon (Si) could lead to improved nutrient uptake and optimized growth and metabolism in rice (Oryza sativa). However, the structural basis and physiological mechanisms of nutrient uptake and metabolism optimization under Si assistance remain obscure. Single-cell level biophysical measurements, including in situ non-invasive micro-testing (NMT) of NH₄⁺ ion fluxes, atomic force microscopy (AFM) of cell walls, and electrolyte leakage and membrane potential, as well as whole-cell proteomics using isobaric tags for relative and absolute quantification (iTRAQ), were performed. The altered cell wall structure increases the uptake rate of the main nutrient NH₄⁺ in Si-accumulating cells, whereas the rate is only half in Si-deprived counterparts. Rigid cell walls enhanced by a wall-bound form of Si as the structural basis stabilize cell membranes. This, in turn, optimizes nutrient uptake of the cells in the same growth phase without any requirement for up-regulation of transmembrane ammonium transporters. Optimization of cellular nutrient acquisition strategies can substantially improve performance in terms of growth, metabolism and stress resistance.

The mimic and design of artificial nanoshell materials on individual cells have been explored in microbial and mammalian cells, and these synthetic interfacial materials can confer new and unique properties on living cells to resist various environmental stresses. However, no attempts have been made toward chemical nanoencapsulation of higher plant cells. Here, we cultivated rice (Oryza sativa) single cells whose cell walls were silicified identically by mimicking diatom biomineralization. Results show that the silica nanoshell at the cell interface is effective at adsorbing cadmium (Cd²⁺) ions by in situ noninvasive microtest technology to quantitatively measure Cd²⁺ ion fluxes, rapidly sequestering and immobilizing Cd ions in the silicified cell walls with adsorption fluxes 6- to 10-times greater than those of the unsilicified cell walls. This, therefore, confers increased Cd tolerance by inhibiting Cd ion uptake into cells. In addition, using in situ atomic force microscopy to probe cell mechanical properties, the cell walls are remarkably strong by virtue of the material properties of the silica nanoshells that physically protects the cells against mechanical challenges. Chemically silicified cells may have acquired a multifunctionality of co-optimized mechanical protection and heavy metal detoxification by organic–inorganic composite materials of the silicified cell walls.