Dissecting phospholipid signalling in Phytophthora infestans

PL1.2 Dissecting phospholipid signalling in Phytophthora infestans Francine Govers Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands Phytophthora, which literally means plant destroyer, is a genus in the Stramenopile lineage in the class oomycetes with over a hundred species. Well known is Phytophthora infestans, the causal agent of potato late blight. Its ~ 240 Mb genome is the largest and most complex in the Stramenopile lineage. Comparative genome analysis revealed features illuminating its success as a pathogen, such as rapid turnover and massive expansion of families encoding secreted proteins and peculiar gene innovations resulting in proteins with oomycete-specific domain combinations. One outstanding class of novel proteins comprises GPCR-PIPKs. The 12 members all have a N-terminal 7-transmembrane domain typical for G-protein coupled receptors (GPCRs) combined with a phosphatidylinositol phosphate kinase (PIPK) domain at the C-terminus. Their differential expression and localization suggest distinct roles in various cellular processes. Another typical class represents secreted proteins with hallmarks of phospholipase D (PLD). We demonstrated PLD activity in medium of mycelium cultures and are currently investigating how these secreted PLDs effect plant cells. Other well-known proteins in the Phytophthora secretome are the RXLR effectors that act inside host cells where they function as virulence factors, mostly by suppressing host defence. In certain interactions they act as avirulence factors that are recognized by corresponding resistance proteins thereby triggering host defence. For the RXLR effector IPI-O, we identified a putative host target and demonstrated that this lectin receptor kinase is a Phytophthora resistance component in Arabidopsis.