Philippar, K. ; Fuchs, I. ; Luthen, H. ; Hoth, S. ; Bauer, C . S. ; Haga, K. ; Thiel, Gerhard ; Ljung, K. ; Sandberg, G. ; Bottger, M. ; Becker, D. ; Hedrich, R. (1999)
Auxin-induced K+ channel expression represents an essential step in coleoptile growth and gravitropism.
In: Proceedings of the National Academy of Sciences of the United States of America, 96 (21)
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

Auxin-induced growth of coleoptiles depends on the presence of potassium and is suppressed by K+ channel blockers. To evaluate the role of K+ channels in auxin-mediated growth, we isolated and functionally expressed ZMK1 and ZMK2 (Zea mays K+ channel 1 and 2), two potassium channels from maize coleoptiles. In growth experiments, the time course of auxin-induced expression of ZMK1 coincided with the kinetics of coleoptile elongation. Upon gravistimulation of maize seedlings, ZMK1 expression followed the gravitropic-induced auxin redistribution. K+ channel expression increased even before a bending of the coleoptile was observed. The transcript level of ZMK2, expressed in vascular tissue, was not affected by auxin. In patch-clamp studies on coleoptile protoplasts, auxin increased K+ channel density while leaving channel properties unaffected. Thus, we conclude that coleoptile growth depends on the transcriptional up-regulation of ZMK1, an inwardly rectifying K+ channel expressed in the nonvascular tissue of this organ.

Frage zum Eintrag

Redaktionelle Details anzeigen