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Titolo:
VFK1, a Vicia faba K+ channel involved in phloem unloading
Autore:
Ache, P; Becker, D; Deeken, R; Dreyer, I; Weber, H; Fromm, J; Hedrich, R;
Indirizzi:
Univ Wurzburg, Julius von Sachs Inst, Lehrstuhl Bot 1, D-97082 Wurzburg, Germany Univ Wurzburg Wurzburg Germany D-97082 Bot 1, D-97082 Wurzburg, Germany Inst Pflanzengenet & Kulturpflanzenforsch, D-06466 Gatersleben, Germany Inst Pflanzengenet & Kulturpflanzenforsch Gatersleben Germany D-06466 ny Univ Munich, Inst Holzforsch, D-80797 Munich, Germany Univ Munich MunichGermany D-80797 t Holzforsch, D-80797 Munich, Germany
Titolo Testata:
PLANT JOURNAL
fascicolo: 6, volume: 27, anno: 2001,
pagine: 571 - 580
SICI:
0960-7412(200109)27:6<571:VAVFKC>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
COMPANION CELL COMPLEX; POTASSIUM CHANNEL; SIEVE ELEMENT; MACROMOLECULAR TRAFFICKING; ARABIDOPSIS-THALIANA; MINERAL NUTRIENTS; PLANT; EXPRESSION; IDENTIFICATION; TRANSPORTERS;
Keywords:
K+ channel; phloem; Vicia faba; sink-source relation; aphid technique; in situ-RT-PCR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
48
Recensione:
Indirizzi per estratti:
Indirizzo: Hedrich, R Univ Wurzburg, Julius von Sachs Inst, Lehrstuhl Bot 1, D-97082 Wurzburg, Germany Univ Wurzburg Wurzburg Germany D-97082 7082 Wurzburg, Germany
Citazione:
P. Ache et al., "VFK1, a Vicia faba K+ channel involved in phloem unloading", PLANT J, 27(6), 2001, pp. 571-580

Abstract

In search of a K+ channel involved in phloem transport we screened a Viciafaba cotyledon cDNA library taking advantage of a set of degenerated primers, flanking regions conserved among K+ uptake channels. We cloned VFK1 (for Vicia faba K+ channel 1) characterised by a structure known from the Shaker family of plant K+ channels. When co-expressed with a KAT1 mutant in Xenopus oocytes, heteromers revealed the biophysical properties of a K+ selective, proton-blocked channel. Northern blot analyses showed high levels of expression in cotyledons, flowers, stem and leaves. Using in situ PCR techniques we could localise the K+ channel mRNA in the phloem. In the stem VFK1 expression levels were higher in the lower internodes. There channel transcripts increased in the light and thus under conditions of increased photosynthate allocation. VFK1 transcripts are elevated in sink leaves, and rise in source leaves during the experimental transition into sinks. Fructose- rather than sucrose- or glucose-feeding via the petiole induced VFK1 gene activity. We therefore monitored the fructose sensitivity of the sieve tube potential through cut aphid stylets. In response to an 1 h fructose treatmentthe sieve tube potential shift increased from 19 mV to 53 mV per 10-fold change in K+ concentration. Under these conditions K+ channels dominated theelectrical properties of the plasma membrane. Based on the phloem localisation and expression patterns of VFK1 we conclude that this K+ channel is involved in sugar unloading and K+ retrieval.

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Documento generato il 04/06/20 alle ore 01:48:51