Present address: Laboratorium voor Genetica, Departement Planten Genetica, Vlaams Interuniversitai, Instituut voor Biotechnologie (VIB), Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium.
Disruption of putative anion channel gene AtCLC-a in Arabidopsis suggests a role in the regulation of nitrate content
Article first published online: 25 DEC 2001
The Plant Journal
Volume 21, Issue 3, pages 259–267, February 2000
How to Cite
Geelen, D., Lurin, C., Bouchez, D., Frachisse, J.-M., Lelièvre, F., Courtial, B., Barbier-Brygoo, H. and Maurel, C. (2000), Disruption of putative anion channel gene AtCLC-a in Arabidopsis suggests a role in the regulation of nitrate content. The Plant Journal, 21: 259–267. doi: 10.1046/j.1365-313x.2000.00680.x
- Issue published online: 25 DEC 2001
- Article first published online: 25 DEC 2001
- Received 23 August 1999; revised 6 January 2000; accepted 6 January 2000.
In animals and yeast, voltage-dependent chloride channels of the CLC family play a role in basic cellular functions such as epithelial transport, plasma membrane excitability, and control of pH and membrane potential in intracellular compartments. To assess the function of CLCs in plants, we searched for CLC insertion mutants in a library of Arabidopsis lines transformed by Agrobacterium tumefaciens transferred DNA (T-DNA). Using a polymerase chain reaction-based screening procedure, an Arabidopsis line that carries a T-DNA insertion within the C-terminus of the AtCLC-a coding sequence was identified. Progeny from this plant line, clca-1, showed dramatically altered transcription of the AtCLC-a gene. Plants homozygous for the clca-1 mutation exhibited normal development and a morphology indistinguishable from the wild-type. However, their capacity to accumulate nitrate under conditions of nitrate excess was reduced in roots and shoots, by approximately 50%, while chloride, sulphate and phosphate levels were similar to the wild-type. In addition, the herbicide chlorate, an analogue of nitrate, induced a faster and more pronounced chlorosis in mutant plants. Hypersensitivity to chlorate as well as decreased nitrate levels co-segregated with the T-DNA insertion. They were found at various time points of the clca-1 life cycle, supporting the idea that AtCLC-a has a general role in the control of the nitrate status in Arabidopsis. Concordant with such a function, AtCLC-a mRNA was found in roots and shoots, and its levels rapidly increased in both tissues upon addition of nitrate but not ammonium to the culture medium. The specificity of AtCLC-a function with respect to nitrate is further supported by a similar free amino acid content in wild-type and clca-1 plants. Although the cellular localization of AtCLC-a remains unclear, our results suggest that AtCLC-a plays a role in controlling the intracellular nitrate status.