Rapid cooling triggers forisome dispersion just before phloem transport stops
| Autor: | Peter E. H. Minchin, Alexandra C. U. Furch, Aart J. E. van Bel, Michael R. Thorpe, Jens Föller, Jens B. Hafke |
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| Rok vydání: | 2010 |
| Předmět: |
Membrane potential
Carbon Isotopes Microscopy Confocal Physiology food and beverages Depolarization Plant Science Phloem Biology Dispersion (geology) Membrane Potentials Vicia faba Cold Temperature Electrophysiology Forisome Membrane Free calcium Botany Biophysics Phloem transport Calcium Microelectrodes Fluorescent Dyes |
| Zdroj: | Plant, Cell & Environment. 33:259-271 |
| ISSN: | 1365-3040 0140-7791 |
| DOI: | 10.1111/j.1365-3040.2009.02079.x |
| Popis: | Phloem transport stops transiently within dicot stems that are cooled rapidly, but the cause remains unknown. Now it is known that (1) rapid cooling depolarizes cell membranes giving a transient increase in cytoplasmic Ca(2+), and (2) a rise of free calcium triggers dispersion of forisomes, which then occlude sieve elements (SEs) of fabacean plants. Therefore, we compared the effects of rapid chilling on SE electrophysiology, phloem transport and forisomes in Vicia faba. Forisomes dispersed after rapid cooling with a delay that was longer for slower cooling rates. Phloem transport stopped about 20 s after forisome dispersion, and then transport resumed and forisomes re-condensed within similar time frames. Transport interruption and forisome dispersion showed parallel behaviour--a cooling rate-dependent response, transience and desensitization. Chilling induced both a fast and a slow depolarization of SE membranes, the electrical signature suggesting strongly that the cause of forisome dispersion was the transient promotion of SE free calcium. This apparent block of SEs by dispersed forisomes may be assisted by other Ca(2+)-dependent sealing proteins that are present in all dicots. |
| Databáze: | OpenAIRE |
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