Microscopy View: Cell bursting Induced By Mercury in Lilium's Pollen Tube

Original video: https://youtu.be/2aKpb9hfv5s Pollen tubes carry the male nuclei by a unique mechanism, replacing the need for motile sperm in all spermatophytes with the partial exception of the primitive gymnosperms. When Hg ions were added to pollen tubes growing in vitro, there was an instantaneous onset of bursting. This phenomenon was observed in Lilium, Mahonia, and Arabidopsis pollen. Using Lilium pollen tubes growing on surface agarose, there was a time-dependent bursting of the cell tips as measured between 0.5min and 4.0min. Although Hg leads to bursting, this must be a specific reaction. (i) Light microscopy video imaging of cells subjected to Hg showed vigorous cytoplasmic streaming right up until the time of tip bursting which, took up to 4min. The growth and streaming was interrupted by the bursting reaction, not by any apparent damage to cell structures. (ii) Cells in which bursting has been prevented by raising the external osmotic pressure with 0.8M sucrose, as in the plasmolysis experiments described above, showed no adverse reactions to Hg ions as judged by microscopic observation; whilst plasmolysis was occurring at the tip, the cells looked normal and exhibited vigorous cytoplasmic streaming. (iii) Although it is a comparatively rare event to catch a bursting tip by electron microscopy, it is possible, and cell organelles are clearly identifiable in and similar to those of steadily growing tubes.

Witness the dramatic effect of mercury on growing pollen tubes! This light microscopy video captures pollen tubes exposed to mercury, leading to tip bursting. What's remarkable is that despite the bursting effect, the pollen tube's cytoplasm continues to stream vigorously right up until the moment of rupture.

Keywords: Lilium, Cell Bursting, Mercury, Pollen, Pollen Tube Cells, Microscopy

Citation:

Bruria Shachar-Hill, Adrian E. Hill, Janet Powell, Jeremy N. Skepper, Yair Shachar-Hill, Mercury-sensitive water channels as possible sensors of water potentials in pollen, Journal of Experimental Botany, Volume 64, Issue 16, November 2013, Pages 5195–5205, https://doi.org/10.1093/jxb/ert311

Published on: 05 October 2013

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