Present address: Institut National de la Recherche Agronomique, UMR Santé et Agroécologie du Vignoble, 71 Av Edouard Bourleaux, 33140 Villenave d'Ornon, France.
Discovery of a multigene family of aquaporin silicon transporters in the primitive plant Equisetum arvense
Article first published online: 6 AUG 2012
© 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd
The Plant Journal
Volume 72, Issue 2, pages 320–330, October 2012
How to Cite
Grégoire, C., Rémus-Borel, W., Vivancos, J., Labbé, C., Belzile, F. and Bélanger, R. R. (2012), Discovery of a multigene family of aquaporin silicon transporters in the primitive plant Equisetum arvense. The Plant Journal, 72: 320–330. doi: 10.1111/j.1365-313X.2012.05082.x
The GenBank/EMBL/DDBJ accession numbers for the sequences described in this paper are HE858197 (EaNIP3;1 cDNA), HE858198 (EaNIP3;2 cDNA), HE858199 (EaNIP3;3 cDNA), HE858200 (EaNIP3;4a CDS), HE858201 (EaNIP3;5 CDS), HE858202 (EaNIP3;6 CDS), HE858203 (EaNIP3;7a CDS), HE858204 (EaNIP3;8 cDNA), HE858205 (EaNIP3;9 CDS), HE858206 (EaPIP1;1 CDS), HE858207 (EaPIP2;1 CDS), HE858208 (EaTIP1;1 CDS) and HE858209 (EaTIP2;1 CDS).
- Issue published online: 16 OCT 2012
- Article first published online: 6 AUG 2012
- Accepted manuscript online: 20 JUN 2012 05:03AM EST
- Received 16 April 2012; revised 8 June 2012; accepted 14 June 2012; published online 6 August 2012.
- NIP aquaporin;
- Equisetum arvense;
Plants benefit greatly from silicon (Si) absorption provided that they contain Si transporters. The latter have recently been identified in the roots of some higher plants known to accumulate high concentrations of Si, and all share a high level of sequence identity. In this study, we searched for transporters in the primitive vascular plant Equisetum arvense (horsetail), which is a valuable but neglected model plant for the study of Si absorption, as it has one of the highest Si concentrations in the plant kingdom. Our initial attempts to identify Si transporters based on sequence homology with transporters from higher plants proved unsuccessful, suggesting a divergent structure or property in horsetail transporters. Subsequently, through sequencing of the horsetail root transcriptome and a search using amino acid sequences conserved in plant aquaporins, we were able to identify a multigene family of aquaporin Si transporters. Comparison of known functional domains and phylogenetic analysis of sequences revealed that the horsetail proteins belong to a different group than higher-plant Si transporters. In particular, the newly identified proteins contain a STAR pore as opposed to the GSGR pore common to all previously identified Si transporters. In order to determine its functionality, the proteins were heterologously expressed in both Xenopus oocytes and Arabidopsis, and the results showed that the horsetail proteins are extremely efficient a transporting Si. These findings offer new insights into the elusive properties of Si and its absorption by plants.