Thursday, February 19, 2015
Rhizobial infection of Lotus japonicus roots is controlled by a two-step recognition process
Centre for Carbohydrate Recognition and Signalling, Department of Molecular Biology and Genetics, Aarhus University, Denmark
Development of root nodules in legumes in response to signals secreted from rhizobia is an example of a regulated bacterial infection process that is synchronised with an inducible organ formation. Lipochito-oligosaccharides (Nod-factors), consisting of substituted Î²,1-4 N-acetylglucosamine (chitin) backbones are the major rhizobial signals triggering root hair deformation, initiation of the bacterial infection process and start of the cell divisions leading to formation of nodule primordia. An important determinant of bacterial recognition and host specificity is the interaction between Nod-factors and the plant receptors involved in signal perception and signal transduction initiating the plant developmental response. In Lotus japonicus there are seventeen LysM receptor kinases that could be involved in perception of Nod-factors or other chitin derived signal molecules. The possible role of these LysM type serine/threonine receptor kinases in plant-microbe interaction will be discussed. Biochemical experiments investigating the function of LysM receptors will be presented and the involvement of NFR1 and NFR5 receptor kinases in the earliest physiological and cellular responses will be illustrated. A second recognition step has recently been discovered and the molecular basis of this novel non-self recognition will be presented together with a model for two-step recognition of rhizobial bacteria at the initiation of infection.
Contact : Guihlem Desbrosses