Powerful screens for bacterial virulence proteins.

The article discusses the efforts employed to discover type III secretion system (TTSS) effectors in plant pathogen. By means of TTSS these pathogens inject virulence effector proteins into host cells. In both mammalian and plant pathogenic bacteria, the initial method for identification of proteins secreted through the TTSS was to monitor extra- cellular proteins secreted in bacterial cultures in a TTSS:dependent manner. Genome-based approaches have also been used successfully to identify TTSS effectors in other plant pathogenic bacteria, including the tomato pathogen Raistonia solanacearum strain GMI1000 (17). The identification of effector repertoires in multiple Pseudomonas syringae pathovars will benefit several aspects of future research on plant-bacteria interactions.