Effector diversity and gene innovations in Phytophthora

Phytophthora literally means plant destroyer, a name coined by the founding father of mycology, Anton de Bary, when he proved that a microorganism was the causal agent of the devastating potato late blight disease. The genus Phytophthora belongs to the oomycetes, a distinct lineage of fungus-like eukaryotes within the supergroup Chromalveolates and related to brown algae and diatoms. The ~ 240 Mb genome of Phytophthora infestans is the largest and most complex in the chromealveolate lineage and its sequence reveals features that illuminate its success as a pathogen. Comparison to other Phytophthora genomes showed rapid turnover and massive expansion of specific families encoding effector proteins, including the host-translocated effectors sharing an RXLR motif. These fast-evolving effector genes are localized to highly dynamic and expanded regions of the P. infestans genome and may attribute to the rapid and successful adaptability of this pathogen to host plants. Other hallmarks reminiscent of a dynamic genome are copy number variations and gene innovations, the latter resulting in proteins with oomycete-specific domain combinations several of which probably have a function in signal transduction