The symbiotic ion channel homolog DMI1 is localized in the nuclear membrane of Medicago truncatula roots
Article first published online: 14 DEC 2006
© 2006 The Authors. Journal compilation © 2006 Blackwell Publishing Ltd
The Plant Journal
Volume 49, Issue 2, pages 208–216, January 2007
How to Cite
Riely, B. K., Lougnon, G., Ané, J.-M. and Cook, D. R. (2007), The symbiotic ion channel homolog DMI1 is localized in the nuclear membrane of Medicago truncatula roots. The Plant Journal, 49: 208–216. doi: 10.1111/j.1365-313X.2006.02957.x
- Issue published online: 14 DEC 2006
- Article first published online: 14 DEC 2006
- Received 7 August 2006; accepted 14 September 2006.
- Medicago truncatula;
- ion channel;
- nuclear localization signal;
Legumes utilize a common signaling pathway to form symbiotic associations both with rhizobial bacteria and arbuscular mycorrhizal fungi. The perception of microbial signals is believed to take place at the plasma membrane, activating a cascade that converges on the nucleus where transcriptional reprogramming facilitates the symbioses. Forward genetic strategies have identified genes in this signaling pathway including Medicago truncatulaDMI1 (Doesn't Make Infections 1) that encodes a putative ion channel. Although the DMI1 homologs from Lotus japonicus, CASTOR and POLLUX, were recently reported to be localized in plastids, we report here that a functional DMI1::GFP fusion is localized to the nuclear envelope in M. truncatula roots when expressed both from a constitutive 35S promoter and from a native DMI1 promoter. Localization may be mediated in part by sequences located within the amino-terminus of DMI1. This region of DMI1 is required for symbiotic signal transduction, and its replacement with a bona fide plastid transit peptide from the glutamine synthetase 2 gene does not restore DMI1 function. These new data place DMI1 in the nuclear envelope in close proximity to the origin of Nod-factor-induced calcium spiking.