These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Auxin activates KAT1 and KAT2, two K+-channel genes expressed in seedlings of Arabidopsis thaliana.
    Author: Philippar K, Ivashikina N, Ache P, Christian M, Lüthen H, Palme K, Hedrich R.
    Journal: Plant J; 2004 Mar; 37(6):815-27. PubMed ID: 14996216.
    Abstract:
    The transcript abundance of the K+-channel gene ZMK1 (Zea mays K+ channel 1) in maize coleoptiles is controlled by the phytohormone auxin. Thus, ZMK1 is thought to function in auxin-regulated coleoptile elongation, as well as during gravitropism and phototropism. To investigate related growth phenomena in the dicotyledonous plant Arabidopsis thaliana, we screened etiolated seedlings for auxin-induced K+-channel genes. Among the members of the Shaker-like K+ channels, we thereby identified transcripts of the inward rectifiers, KAT1 (K+ transporter of Arabidopsis thaliana) and KAT2, to be upregulated by auxin. The phloem-associated KAT2 was localised in cotyledons and the apical part of etiolated seedlings. In contrast, the K+-channel gene KAT1 was expressed in the cortex and epidermis of etiolated hypocotyls, as well as in flower stalks. Furthermore, KAT1 was induced by active auxins in auxin-sensitive tissues characterised by rapid cell elongation. Applying the patch-clamp technique to protoplasts of etiolated hypocotyls, we correlated the electrical properties of K+ currents with the expression profile of K+-channel genes. In KAT1-knockout mutants, K+ currents after auxin stimulation were characterised by reduced amplitudes. Thus, this change in the electrical properties of the K+-uptake channel in hypocotyl protoplasts resulted from an auxin-induced increase of active KAT1 proteins. The loss of KAT1-channel subunits, however, did not affect the auxin-induced growth rate of hypocotyls, pointing to compensation by residual, constitutive K+ transporters. From gene expression and electrophysiological data, we suggest that auxin regulation of KAT1 is involved in elongation growth of Arabidopsis. Furthermore, a role for KAT2 in the auxin-controlled vascular patterning of leaves is discussed.
    [Abstract] [Full Text] [Related] [New Search]