Measuring the growth force of invasive plant cells using Flexure integrated Lab-on-a-Chip (FiLoC)

Abstract

The pollen tube is a tip growing cell that is able to invade plant tissues in order to accomplish its function — the delivery of sperm cells to the ovule. The pistillar tissues through which the tube has to elongate represent a formidable mechanical obstacle, but it is unknown how much force the growing tube is able to exert, or how mechanical impedance affects its growth behavior. We quantified the invasive force of individual pollen tubes using a microfluidic lab-on-a-chip device featuring a microscopic cantilever. Using finite element method the maximum invasive growth force of the growing pollen tube was determined to be in the microNewton range. Real time monitoring revealed that contact with the mechanical obstacle caused a shift in the peak frequency characterizing the oscillatory behavior of the pollen tube growth rate. This suggests the presence of a feedback-based control mechanism with a mechanical regulatory component.