Diversify and conquer: How effector diversity is shaped by host–microbe co-evolution

Effectors are diverse molecules produced and secreted by plant pathogens to facilitate infection often by exerting an "effect" on their host.The production of effector molecules is a ubiquitous feature of plant pathogens.Because many effector proteins act on host targets and are subject of host immune detection, the corresponding effector genes co-evolve with the corresponding host genes involved in immunity or susceptibility.This co-evolution results in diversity at effector loci, both within and between lineages/species.Here, we examine the diverse patterns and consequences of variation observed across the sequence and regulatory landscapes of effector genes and summarize the genomic mechanisms that create them.