Journal Article

PreJuSER-8364

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Rapid cooling triggers forisome dispersion just before phloem transport stops

Thorpe, M. R.FZJ* ; Furch, A. C. U. ; Minchin, P. E. H. ; Föller, J. ; Van Bel, A. J. E. ; Hafke, J. B.

2010
Wiley-Blackwell Oxford [u.a.]

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Please use a persistent id in citations: doi:10.1111/j.1365-3040.2009.02079.x

Abstract: 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.

Keyword(s): Calcium: metabolism (MeSH) ; Carbon Isotopes: analysis (MeSH) ; Cold Temperature (MeSH) ; Electrophysiology (MeSH) ; Fluorescent Dyes (MeSH) ; Membrane Potentials (MeSH) ; Microelectrodes (MeSH) ; Microscopy, Confocal (MeSH) ; Phloem: physiology (MeSH) ; Vicia faba: physiology (MeSH) ; Carbon Isotopes ; Fluorescent Dyes ; Calcium ; J ; 11C (auto) ; burning (auto) ; C-11 (auto) ; carbon-11 (auto) ; chill (auto) ; cold (auto) ; cooling (auto) ; transport blockage (auto)

Note: We were supported by the Deutsche Forschungsgemeinschaft in the frame of the Schwerpunktprogramm 1108 (BE 1925/8-2, 8-3, 15-1) and by the Marsden Fund of New Zealand (Contract Number UOW003). We acknowledge Gerhard Roeb, Siegfried Jahnke and Marco Dautzenberg for discussions and technical assistance in Julich, and Werner Uhmann, Thomas Wagner, Andreas Reh and Stefan Balser in Giessen for expert workshop assistance in Giessen.

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Research Program(s):

1. Terrestrische Umwelt (P24)

Appears in the scientific report 2010

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