Many gram-negative bacteria use the type Ⅲ secretion system (T3SS) to inject virulence proteins (effectors) directly into host cells.These effectors play a central role in pathogen interactions,and their molecular structures are highly variable.Previous researchers have used particular motifs common to all effectors in order to identify a full suite of candidate effectors of T3SS in the genome of Pseudomonas syringae.Here,we present a program called EFFECTORSEARCH that synthesizes and extends previous work by allowing users to identify candidate effectors based on any combination of the following five criteria:protein length,proximity to the hrp promoter,n-terminal region,similarity to known effectors,and dissimilarity to housekeeping genes.We demonstrate the utility of the program in allowing users either to search broadly for candidates or to restrict attention to the candidates with the highest confidence in their assignment.