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Poster: Molecular & Cellular Plant-Microbe Interactions: MPMI


A band of misfits: role of unexpected proteins in the plant symbiotic signaling pathway
M. Venkateshwaran (1), A. Wiley-Kalil (2), D. Jayaraman (3), M. Banba (4), A. Binder (5), S. Bernard (6), J. Maeda (6), M. Otegui (7), H. Imaizumi-Anraku (8), M. Parniske (5), J. Ané (9) (1) University of Wisconsin-Platteville, U.S.A.; (2) NDSU Williston

Rhizobia and arbuscular mycorrhizal fungi produce lipo-chito-oligosaccharidic signals that are perceived by legume hosts at the plasma membrane level. These signals are then transduced to the nucleus where they trigger oscillations of the nuclear calcium concentration (calcium spiking) that, in turn, regulates symbiotic gene expression. Genetic and protein interaction studies identified some relatively expected components in such a signaling pathway: receptor-like kinases at the plasma membrane that perceive the microbial signals, ion channels and ion pumps on the nuclear envelope that allow calcium spiking, and nuclear transcription factors that regulate gene expression. We will present new data on more unexpected members of this signaling pathway. (1) An HMGR (3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase) that interacts with and is regulated by the symbiotic receptor kinases. In particular, we will show that the activity of this HMGR is not only necessary but also sufficient to trigger calcium spiking. (2) Nucleoporins of the NUP107-160 sub-complex that have been identified through forward genetic approaches. We will show that these nucleoporins are required for the proper localization of symbiotic ion channels to the inner nuclear membrane. Finally, we will compare results between two legumes, Medicago truncatula and Lotus japonicus, and show the value of comparing carefully these two genetic systems.