Present address: University of Bonn, Botanical Institute, Kirschallee 1, 53115 Bonn, Germany.
The Nod factor-elicited annexin MtAnn1 is preferentially localised at the nuclear periphery in symbiotically activated root tissues of Medicago truncatula
Article first published online: 31 OCT 2002
The Plant Journal
Volume 32, Issue 3, pages 343–352, November 2002
How to Cite
De Carvalho-Niebel, F., Timmers, A. C. J., Chabaud, M., Defaux-Petras, A. and Barker, D. G. (2002), The Nod factor-elicited annexin MtAnn1 is preferentially localised at the nuclear periphery in symbiotically activated root tissues of Medicago truncatula. The Plant Journal, 32: 343–352. doi: 10.1046/j.1365-313X.2002.01429.x
- Issue published online: 31 OCT 2002
- Article first published online: 31 OCT 2002
- Received 26 April 2002; revised 2 July 2002; accepted 7 July 2002.
- root nodulation;
- symbiotic signalling
The Medicago truncatula MtAnn1 gene, encoding a putative annexin, is transcriptionally activated in root tissues in response to rhizobial Nod factors. To gain further insight into MtAnn1 function during the early stages of nodulation, we have examined in detail both spatio-temporal gene expression patterns and MtAnn1 activity and localisation in root tissues. Analysis of transgenic Medicago plants expressing a pMtAnn1-GUS fusion has revealed a novel pattern of transcription in both outer and inner cell layers of the root following either Nod factor-treatment or rhizobial inoculation. The highest gene expression levels were observed in the endodermis and outer cortex. These transgenic plants also revealed that MtAnn1 expression is associated with lateral root development and cell differentiation in the root apex independent of nodulation. By purifying recombinant MtAnn1 we were able to demonstrate that this plant annexin indeed possesses the calcium-dependent binding to acidic phospholipids typical of the annexin family. Antisera against recombinant MtAnn1 were then used to show that tissue-specific localisation of the MtAnn1 protein in Medicago roots matches the pMtAnn1-GUS expression pattern. Finally, both immunolabelling and in vivo studies using MtAnn1-GFP reporter fusions have revealed that MtAnn1 is cytosolic and in particular localises to the nuclear periphery in cortical cells activated during the early stages of nodulation. In the light of our findings, we discuss the possible role of this annexin in root tissues responding to symbiotic rhizobial signals.