Translocation of RXLR effector Pi04314 from Phytophthora infestans into plant cells to form holoenzymes with host protein phosphatase PP1c
P. BIRCH (1), P. Boevink (2), S. Wang (1), X. Wang (3), H. McLellan (3), S. Naqvi (3), Q. He (3), M. armstrong (4), Z. Tian (5), I. hein (4), E. Gilroy (4), S. whisson (4) (1) University of Dundee, United Kingdom; (2) James Hutton Institute, United Kingdom; (3) University of Dundee, United Kingdom; (4) James Hutton Institute, United Kingdom; (5) Huazhong Agricultural University, China

Plant pathogens deliver effectors to alter host processes. Knowledge of how effectors target and manipulate host proteins is critical to understand crop disease. We show that transient in planta expression of RXLR effector Pi04314 enhances leaf colonisation by the potato pathogen Phytophthora infestans via activity in the host nucleus. The effector attenuates jasmonic and salicylic acid based defence responses. Pi04314 interacts with three host protein phosphatase 1 catalytic (PP1c) isoforms, causing their re-localization from the nucleolus to the nucleoplasm. Re-localisation of PP1c-1 also occurs during infection and is dependent on an R/KVxF motif in the effector, indicating that the effector mimics PP1c regulatory subunits. Silencing the PP1c isoforms or overexpression of a phosphatase-dead PP1c-1 mutant (PP1c-1mut) attenuates infection, demonstrating that host PP1c activity is required for disease. Moreover, expression of PP1c-1mut abolishes enhanced leaf colonisation mediated by in planta Pi04314 expression. We provide evidence that PP1c isoforms are susceptibility factors forming holoenzymes with Pi04314 to promote late blight disease. We also show that Pi04314-mRFP, expressed in stable transgenic P. infestans lines, is translocated into host cells to accumulate in the host nucleolus. This presents the first visualisation of translocation of an intracellular effector from an oomycete into the cells of its host, and offers a unique opportunity to revisit the mechanistic basis of effector translocation.

Abstract Number: P9-239
Session Type: Poster