Pathogenomics of fungal plant parasites: what have we learnt about pathogenesis?

Members of the kingdom fungi comprise numerous plant pathogens, including the causal agents of many agriculturally relevant plant diseases such as rust, powdery mildew, rice blast and cereal head blight. Data from recent sequencing projects provide deep insight into the genomes of a range of fungi that infect different organs of monocotyledonous or dicotyledonous hosts and that have diverse pathogenic lifestyles. These studies have revealed that, similar to sequenced phytopathogenic oomycetes, these plant parasites possess very plastic and dynamic genomes, which typically encode several hundred candidate secreted effector proteins that can be highly divergent even among related species. A new insight is the presence of lineage-specific genes on mobile and partly dispensable chromosomes that are transferred intraspecifically and possibly interspecifically, thereby constituting pathogenicity and host range determinants. Convergent lifestyle-specific adaptations have shaped the parasite genomes to maximize pathogenic success according to the different infection strategies employed. ⺠Filamentous plant pathogens have unexpectedly plastic and dynamic genomes. ⺠These genomes typically encode hundreds of rapidly evolving effector proteins. ⺠Many virulence-associated genes are located proximal to transposable elements. ⺠Numerous phytopathogens have dispensable lineage-specific (mini-) chromosomes. ⺠Horizontal gene along with chromosome transfer is a host range determinant.