Cell Wall Biochemistry Drives Pollen Tube Mechanics and Affects Growth Rate

SUMMARY Pollen tubes live a life on a razor’s edge. They must maintain cell wall integrity whilst growing towards the ovule at extraordinary speed but explosively burst at just the right moment to release the sperm cells—with fatal consequences for reproduction if things go wrong. The precisely controlled growth of the pollen tube depends on the fine-tuned balance between the expansive force of turgor pressure and the restraining effect of the cell wall. Currently, it is not well understood how the composition of the cell wall affects its mechanical properties. Using Arabidopsis mutants, we have investigated these interactions by combining experimental and simulation techniques to determine instantaneous and time-dependent mechanical parameters. This allowed, for the first time, the quantification of the effects of cell wall biochemistry on turgor pressure and cell wall elasticity and to predict their effects on growth rate. Our systems biology approach is widely applicable to study the implications of mechanical stress on growth.