Large Electrical Currents Traverse Growing Pollen Tubes

• Published in: The Journal of cell biology 1975-09, Vol.66 (3), p.556-567
• Main Authors: Weisenseel, Manfred H., Nuccitelli, Richard, Jaffe, Lionel F.
• Format: Article
• Language: English
• Subjects: Calcium; Cell membranes; Current density; Cytochalasin B - pharmacology; Cytochalasins; Cytoplasmic Streaming; Eggs; Electric current; Electric fields; Electrophysiology; Plant Development; Plant Physiological Phenomena; Plants - drug effects; Pollen; Pollen tubes; Streaming; Surface Properties
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.66.3.556

Using a newly developed vibrating electrode, we have explored the electric fields around lily pollen germinating in vitro. From these field measurements, we infer that each wetted pollen drives a steady current of a few hundred picoamperes through itself. Considered as a flow of positive ions, this current enters an ungerminated grain's prospective growth site and leaves its opposite end. After a grain germinates and forms a tube, this current enters most of the growing tube and leaves the whole grain. The current densities over both of these extended surface regions are relatively uniform, and the boundary zone, near the tube's base, is relatively narrow. This current continues as long as the tube grows, and even continues when elongation, as well as cytoplasmic streaming, are blocked by 1 μg/ml of cytochalasin B. After an otherwise indistinguishable minority of tubes have grown to lengths of a millimeter or more, their current comes to include an endless train of discrete and characteristic current pulses as well as a steady component. These pulses are about 30 s long, never overlap, recur every 60-100 s, and seem to enter a region more restricted to the growing tip than the steady current's sink. In most ways, the current through growing lily pollen resembles that known to flow through fucoid eggs.