|Date||Aug. 6, 2012 15:00 – 16:00|
Title: "Network properties of plant immunity"
Speaker: Kenichi Tsuda, Ph.D (Max-Planck-Institute for Plant Breeding Research, Cologne, Germany)
Plants sense molecules originating from microbes and turn on a battery of immune responses. Two modes of plant immunity, Pattern-Triggered Immunity (PTI) and Effector Triggered Immunity (ETI), are well-defined. PTI is provoked by recognition of conserved molecules shared by many microbes. ETI is triggered by specific recognition of effectors which are delivered by adapted pathogens to dampen host immunity. PTI is typically associated with weak and vulnerable immune responses, while ETI induces strong and robust immune responses. A traditional approach, knocking out one mechanism at a time, has revealed little about major parts of the signaling network. By simultaneously knocking out four major signaling sectors in the plant immune network (quadruple mutant), we demonstrated that a common network comprised of the four signaling sectors accounts for most of PTI and ETI triggered by particular molecules. Thus, different modes of immunity use the common core signaling sectors although immune outputs are distinct. We computationally estimated how much each signaling sector contributes to PTI and ETI and studied how the signaling sectors work together using all combinatorial (single, double and triple) mutants. We found that signaling sectors work together synergistically in PTI, which may amplify the signal, while they compensate one another in ETI to make the immune signaling network highly resistant to pathogen attack. Thus, different modes of plant immunity share the same signaling machinery, but they use the same machinery in very different ways in order to achieve particular properties and outputs. I will discuss how plants may achieve this and why plants use the immune network in this way.