Watching acquired resistance unfold before our eyes

A major challenge in modern biology is the visualization of biochemical pathways in living cells. Subramaniam et al. report on the application of a new technology called ‘protein fragment complementation assays’ (PCAs), which is used to visualize a key step in a signal transduction pathway underlying systemic acquired resistance in higher-plant cells. Their results suggest a wide range of potential applications of their strategy in visualizing biochemical processes and in determining gene function.