Arabidopsis thaliana Cyclic Nucleotide Gated Channel 3 forms a non-selective ion transporter involved in germination and cation transport

• Published in: Journal of experimental botany 2006-03, Vol.57 (4), p.791-800
• Main Authors: Gobert, Anthony, Park, Graeme, Amtmann, Anna, Sanders, Dale, Maathuis, Frans J. M
• Format: Article
• Language: English
• Subjects: Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Arabidopsis thaliana; Biological and medical sciences; cation; Cations; Cell physiology; CNGC3; cortex; Cyclic Nucleotide Gated Channel; Cyclic Nucleotide-Gated Cation Channels; Cyclic nucleotides; DNA, Bacterial - genetics; Epidermal cells; epidermis (plant); Fundamental and applied biological sciences. Psychology; gene expression; genes; Genes, Reporter; Germination; Ion channels; Ion Channels - genetics; Ion Channels - metabolism; Ion Channels - physiology; Ion Transport; Ions; Mutagenesis, Insertional; mutants; Phenotype; Plant growth; Plant physiology and development; Plants; plasma membrane; Plasma membrane and permeation; Potassium - metabolism; potassium chloride; protein transport; recombinant fusion proteins; Recombinant Fusion Proteins - metabolism; reporter genes; Research Papers; resistance mechanisms; reverse genetics; roots; seed germination; seedling growth; Seedlings; shoots; Sodium - metabolism; sodium chloride; transgenic plants; Yeasts; Yeasts - genetics
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erj064

The Arabidopsis thaliana genome contains 20 cyclic nucleotide gated channel (CNGC) genes encoding putative non-selective ion channels. Classical and reverse genetic approaches have revealed that two members of this family (CNGC2 and CNGC4) play a role in plant defence responses whereas CNGC1 and CNGC10 may participate in heavy metal and cation transport. Yet, it remains to be resolved how the ion transport attributes of CNGCs are integrated into their physiological function. In this study, CNGC3 is characterized through heterologous expression, GUS- and GFP-reporter gene fusions, and by adopting a reverse genetics approach. A CNGC3-GFP fusion protein shows that it is mainly targeted to the plasma membrane. Promoter GUS studies demonstrate CNGC3 expression predominantly in the cortical and epidermal root cells, but also a ubiquitous presence in shoot tissues. Expression of CNGC3 in yeast indicates it can function as a Na⁺ uptake and a K⁺ uptake mechanism. cngc3 null mutations decreased seed germination in the presence of NaCl but not KCl. Relative to the wild type, mutant seedling growth is more resistant to the presence of toxic concentrations of NaCl and KCl. The ionic composition and ion uptake characteristics of wild-type and mutant seedlings suggests that the growth advantage in these conditions may be due to restricted ion influx in mutant plants, and that CNGC3 functions in the non-selective uptake of monovalent cations in Arabidopsis root tissue.