Symbioses: Plant, Animal, and Microbe Interactions
Messinese, Elsa , Riely, Brendan K. , Venkateshwaran, Muthusubramanian , Peiter, Edgar , Mun, Jeong-Hwan , Yeun, Li Huey , Jayaraman, Dhileepkumar , Lougnon, Geraldine , Bono, Jean-Jacques , Sanders, Dale , Cook, Douglas R. , Ane, Jean-Michel .
The nucleus as a central player in symbiotic signaling.
Nod factors are lipochitooligosaccharides produced by symbiotic rhizobia and able to elicit, in legume hosts, responses similar to those induced by the rhizobia themselves such as nucleus-associated calcium spiking and nodulin gene expression. Several genes involved in Nod factor signaling have been cloned recently in model legumes through forward genetic approaches. Among them, DMI1 (Does not Make Infections 1) encodes a putative ion channel required for calcium spiking and DMI3 encodes a calcium/calmodulin dependent kinase (CCaMK) probably transducing the calcium signal into a phosphorylation cascade. Both genes are required for the establishment of legume nodulation as well arbuscular mycorrhization. While the DMI1 homologs from Lotus japonicus, CASTOR and POLLUX, have been localized in plastids, we found that a functional DMI1::GFP fusion localizes to the nuclear envelope in Medicago truncatula roots when expressed either from a constitutive 35S promoter or from a native promoter. Localization may be mediated in part by sequences located within the N-terminus of DMI1. We also showed that DMI1 modulates the release of calcium in plants and also in yeasts. DMI3 has been localized in the nucleus and we have identified by yeast-two-hybrid a novel protein interacting with DMI3 named IPD3 (Interacting Protein of DMI3). IPD3 is predicted to interact with DMI3 through a C-terminal coiled-coil domain. Chimeric IPD3::GFP also localizes to the nucleus of transformed M. truncatula root cells. Split yellow fluorescent protein assays suggest that IPD3 and DMI3 physically interact in plant nuclei. Like DMI3, IPD3 is extremely well conserved among the angiosperms but seems absent from Arabidopsis. Progress towards the characterization of these nuclear proteins will be reported.
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1 - University of Wisconsin Madison, Agronomy
2 - University of California Davis, Plant Pathology
3 - University of York, Biology
4 - Centre National de la Recherche Scientifique, UMR 5546
5 - University of Wisconsin Madison, Agronomy, 348 Moore Hall, 1575 Linden Drive, Madison, WI, 53706, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Continental B/Hilton
Date: Wednesday, July 11th, 2007
Time: 1:00 PM