%0 Journal Article %1 RN1198 %A Langer, K. %A Ache, P. %A Geiger, D. %A Stinzing, A. %A Arend, M. %A Wind, C. %A Regan, S. %A Fromm, J. %A Hedrich, R. %D 2002 %J Plant Journal %K channel k+ myOwn %N 6 %P 997-1009 %R DOI 10.1046/j.1365-313X.2002.01487.x %T Poplar potassium transporters capable of controlling K homeostasis and K -dependent xylogenesis %U /brokenurl#<Go to ISI>://WOS:000180062100012 %V 32 %X The cambial K+ content of poplar increases during the growth period in a K+ supply dependent manner. Upon K+ starvation or application of tetraethylammoniumchloride (TEA(+) ), a K+ channel blocker, the average vessel lumen and expansion zone area were significantly reduced. In search for the molecular basis of potassium-dependent xylogenesis in poplar, K+ transporters homologous to those of known function in Arabidopis phloem- and xylem-physiology were isolated from a poplar wood EST library. The expression profile of three distinct K+ channel types and one K+ transporter, Populus tremula K+ uptake transporter 1 (PtKUP1), was analysed by quantitative RT-PCR. Thereby, we found P. tremula outward rectifying K+ channel (PTORK) and P. tremula K+ channel 2 (PTK2) correlated with the seasonal wood production. K+ transporter P. tremula 1 (KPT1) was predominantly found in guard cells. Following the heterologous expression in Xenopus oocytes the biophysical properties of the different channels were determined. PTORK, upon membrane de-polarization mediates potassium release. PTK2 is almost voltage independent, carrying inward K+ flux at hyperpolarized potential and K+ release upon de-polarization. PtKUP1 was expressed in a K+ uptake-deficient Escherichia coli strain, where this K+ transporter rescued K+ -dependent growth. In order to link the different K+ transporters to the cambial activity and wood production, we compared the expression profiles to seasonal changes in the K+ content of the bark as well as xylem vessel diameter. Thereby, we found PTORK and PTK2 transcripts to follow the annual K+ variations in poplar branches. PtKUP1 was expressed at a low level throughout the year, suggesting a housekeeping function. From these data, we conclude that K+ channels are involved in the regulation of K+ -dependent wood production.

@article{RN1198, abstract = {The cambial K+ content of poplar increases during the growth period in a K+ supply dependent manner. Upon K+ starvation or application of tetraethylammoniumchloride (TEA(+) ), a K+ channel blocker, the average vessel lumen and expansion zone area were significantly reduced. In search for the molecular basis of potassium-dependent xylogenesis in poplar, K+ transporters homologous to those of known function in Arabidopis phloem- and xylem-physiology were isolated from a poplar wood EST library. The expression profile of three distinct K+ channel types and one K+ transporter, Populus tremula K+ uptake transporter 1 (PtKUP1), was analysed by quantitative RT-PCR. Thereby, we found P. tremula outward rectifying K+ channel (PTORK) and P. tremula K+ channel 2 (PTK2) correlated with the seasonal wood production. K+ transporter P. tremula 1 (KPT1) was predominantly found in guard cells. Following the heterologous expression in Xenopus oocytes the biophysical properties of the different channels were determined. PTORK, upon membrane de-polarization mediates potassium release. PTK2 is almost voltage independent, carrying inward K+ flux at hyperpolarized potential and K+ release upon de-polarization. PtKUP1 was expressed in a K+ uptake-deficient Escherichia coli strain, where this K+ transporter rescued K+ -dependent growth. In order to link the different K+ transporters to the cambial activity and wood production, we compared the expression profiles to seasonal changes in the K+ content of the bark as well as xylem vessel diameter. Thereby, we found PTORK and PTK2 transcripts to follow the annual K+ variations in poplar branches. PtKUP1 was expressed at a low level throughout the year, suggesting a housekeeping function. From these data, we conclude that K+ channels are involved in the regulation of K+ -dependent wood production.}, added-at = {2024-02-14T14:38:32.000+0100}, author = {Langer, K. and Ache, P. and Geiger, D. and Stinzing, A. and Arend, M. and Wind, C. and Regan, S. and Fromm, J. and Hedrich, R.}, biburl = {https://www.bibsonomy.org/bibtex/29769c2c7e45f9fffc5175c92ac21d504/rainerhedrich_2}, doi = {DOI 10.1046/j.1365-313X.2002.01487.x}, interhash = {f02cb8db351eace57097c08971a0a3e8}, intrahash = {9769c2c7e45f9fffc5175c92ac21d504}, issn = {0960-7412}, journal = {Plant Journal}, keywords = {channel k+ myOwn}, note = {629rf Times Cited:80 Cited References Count:58}, number = 6, pages = {997-1009}, timestamp = {2024-02-14T14:38:32.000+0100}, title = {Poplar potassium transporters capable of controlling K homeostasis and K -dependent xylogenesis}, type = {Journal Article}, url = {/brokenurl#<Go to ISI>://WOS:000180062100012}, volume = 32, year = 2002 }