Molecular Plant Biophysics and Biochemistry

Pollen (systems) biology – How do pollen grains germinate and how do pollen tubes grow?
Our working hypothesis is that ion channels and pumps of the plasma membrane generate an electrical field around the pollen grain and the growing tube which provides a 3-dimensional, polar electrical field for the tube’s growth direction. The various ion transporters can be characterized by electrophysiological techniques using pollen protoplasts but also in organelle-enriched vesicle preparations. In addition, molecular biological methods are used to identify ion transporter sequences involved in the tip growth process. So far, we have characterized and identified K+ channels, H+ ATPases, and aquaporins of the plasma membrane.
Although a detailed characterization of single ion transporters helps to understand their specific role during pollen tube growth, a comprehensive view of the entire proteins during germination and tube growth can provide new insights into the polar growth process. Therefore, after studying membrane and membrane-associated proteins in pollen by a membrane proteome analysis (Pertl et al 2009), we identified the lily pollen transcriptome (Lang et al. 2015), characterizing specific protein-protein interactions (PM H+ ATPase interactome: Pertl-Obermeyer et al. 2014) and studied metabolic pathways networks (Obermeyer et al. 2013) that dynamically change during germination and growth of pollen tubes. By using this systems biological (multi-omics) approach one may map the pollen system in a mathematical model to obtain a comprehensive description of the pollen tube growth process.