(176n) Microfluidic Approaches to the Study of Chemotropism in Plant Cells

A wide variety of living cells responds to the gradient of diffusible substances and exhibit distinct directional cell growth, which refers to as chemotropism. A pollen tube is a tip-growing cell found in flowering plants that shows chemotropism in response to signaling cues from female gametes. A pollen tube encloses immobile sperm cells inside and elongates through a pistil and approaches to the target ovules for fertilization. While the molecular processes that regulate the pollen tube guidance have not yet been conclusively revealed, several pollen tube attractants as well as their receptors have been discovered recently. With this background, there is an increased need to develop the method to assess those attractants and candidate molecules responsible for the pollen tube guidance.

In this work, we have developed microfluidic-based chemotropism assay for Arabidopsis thaliana pollen tubes. A stable attractant gradient was generated in the microdevice, and the cellar responses to the signaling cues were analyzed by time-lapse imaging. In addition to this study, we have investigated the possibility that pollen tubes may have an ability to respond to single attractant molecules. Employing an electrokinetic technique, we have developed a microfluidic injector that enables us to apply single attractant molecules at the tip of a growing pollen tube. Such a microfluidic approach may elucidate the mechanism of pollen tube guidance at single-molecular resolution.