Figure 1.

A proposed framework for developing a systems tip growth model for a pollen tube. (1) New membrane is formed at the tip when growth occurs. Due to an oscillatory growth rate, L_a and L_b may not be equal for the same time interval, Δt. (2) Addition of new membranes causes the redistribution of ion transporters across the membrane. The process is dynamical and it corresponds to the process for the addition of new membranes in pollen tube growth; (3–6) Pollen tube growth, ion dynamics, mechanical properties of the membranes and other factors that regulate growth and ion dynamics all form entangled dynamical systems and they regulate each other. Development of a systems tip growth model for a pollen tube requires integration of all the processes highlighted in Figure 1 into a dynamical system.