Polar-localised poplar K+ channel capable of controlling electrical properties of wood-forming cells.
In previous studies, we have shown that annual expression profiles of cambial and wood tissue with respect to the Shaker K+ channel PTORK correlate with cambial activity. To follow PTORK-gene activity on the cellular level, we isolated the respective promoter regions and generated transgenic Arabidopsis plants expressing the GUS gene under the control of the PTORK promoter. Cross-sections of petioles showed PTORK-driven signals predominantly in the xylem parenchyma surrounding the vessels and in the phloem. Antibodies raised against a unique N-terminal region of PTORK in histo-immunochemical analyses recognised this K+-release channel in growth-active poplar plants only. PTORK labelling was found in differentiating xylem cells (young fibres) and mature xylem (vessel-associated cells of the ray parenchyma). Patch-clamp measurements on fibre cell protoplasts, derived from young poplar twigs, identified outward-rectifying K+ channels as the major K+ conductance of this cell type, which resembled the biophysical properties of PTORK when expressed in Xenopus oocytes.
Arend
Matthias
M
FG Holzbiologie der TU München, Winzererstrasse 45, 80797 Münich, Germany.
Stinzing
Andrea
A
Wind
Christa
C
Langer
Katharina
K
Latz
Andreas
A
Ache
Peter
P
Fromm
Jörg
J
Hedrich
Rainer
R
D000595:Amino Acid Sequence; D000906:Antibodies / Q000276:immunology; D017360:Arabidopsis / Q000235:genetics; D004594:Electrophysiology; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D018547:Plant Stems / Q000166:cytology / Q000502:physiology; D030821:Plants, Genetically Modified; D032107:Populus / Q000166:cytology / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011523:Protoplasts; D051637:Shaker Superfamily of Potassium Channels / Q000032:analysis* / Q000235:genetics; D014934:Wood
D000906:Antibodies; D051637:Shaker Superfamily of Potassium Channels