In biology, electrotropism, also known as galvanotropism,[1] is a kind of tropism which results in growth or migration of an organism, usually a cell, in response to an exogenous electric field.
[6] They are easily cultivated in vitro and have a very dynamic cytoskeleton that polymerizes at very high rates, providing the pollen tube with interesting growth properties.
Plant growth in response to electric signals and fields has been studied by some researchers; however, it has not been as widely tested on pollen tubes.
This behavioral response allows pollen tubes to attack flower pistils and drop off sperm cells to ovules for fertilization.
The model organism used by the researcher was Camellia japonica pollen, because it displayed a differential sensitivity to the electrical fields when different parts of the tube were exposed.
Analyzing the plant’s homeostatic conditions and implementing it in the experiment, the researchers exposed parts of the pollen tube that were either the whole cell or the growing tip to see how growth occurs in response to an external field.
The pollen tube serves as a useful model because it is similar to a nerve ending which conducts electrical signaling in humans and animals.
The experiment that the researchers conducted to support their hypothesis was that they suspended Camellia japonica pollen into an electrical field.
Pollen was thawed and rehydrated in a humid atmosphere for one hour before submersion in liquid growth medium and injection into the chip.
To ensure reproducibility of test conditions, no dyes were implemented, no extreme voltages were applied, and pollen from the same plant and flowering season was used as not to be confounders in the experiment.
[10] Tomato and tobacco pollen tubes grew towards the positive electrode for constant electric fields higher than 0.2 V/cm.
[4] Agapanthus umbelatus pollen tubes grow towards the nearest electrode when a constant electric field of 7.5 V/cm is applied.
[9] The critical field strength that inhibited pollen performance when the entire cell (including grain) was exposed was approximately 10 V/cm.
This finding may be explained by differences in ion transport behaviour in these two cellular regions, and is consistent with the extremely polar organization of the cell.
Although the authors did not delve deep in the physiology of how electric fields affect plants, they did propose that ions are being regulated during this experiment.
This experiment performed by the researchers shows that electrical fields and forces that exist in plants can shape their external and internal structures.
It is suggested that magnetic field intensity and duration can influence the root and shoot growth of Uslu grape scions.
In the specific study, the application of 0.15 mT at 50 Hz for 10 and 15 minutes gave rise to the highest shoot length and plant weight.
This result stays consistent when the electric field is applied locally to either the CEZ or DEZ individually, showing that it is not an overall gravitropic response.