Functional analysis of plant-pathogenic oomycete effectors and their targets inside plant cell (POETIC)

MARIE-CECILE CAILLAUD; SOPHIE J. M. PIQUEREZ; FABRO GEORGINA; NAVEED ISHAQUE; SUE DONOVAN; BEYNON, J.; JONATHAN D. G. JONES

Praga

Congreso; Society for Experimental Biology Main Meeting, Prague 2010; 2010

Society for Experimental Biology

Plant-associated organisms secrete moleculesto attenuate plant defence signalling and enablecolonization of plant tissue. Like fungal rust and powderymildew pathogens, oomycetes form specializedfeeding structures “haustoria”. Pathogen effectors aretranslocated via haustoria into host cells for haustorialestablishment and maintenance, to immunocompromisethe host and for establishing the infection site as ametabolic sink. The effectors are presumed to be firstsecreted from the pathogen, and then taken up by thehost cell, perhaps by endocytosis, via an N-terminalRxLR uptake motif. Hitherto, in planta subcellularlocalisation of effectors translocated from oomycetesinto the plant cell was not achieved, though this wasachieved for bean rust. As part of a contribution to anERA-PG project coordinated by Jim Beynon, the Joneslaboratory tested candidate effector genes mined fromthe genome sequence of Arabidopsis downy mildew(Hyaloperonospora arabidopsidis -Hpa) using P. syringaevia type III secretion. They identified ~65 effectorsthat confer enhanced/decreased virulence of Pst onat least one Arabidopsis accession, and 35 have beenprioritized. We aim to analyse in planta, the modes ofaction of promising RxLR effectors from Hpa that conferenhanced/decreased virulence. The main objectives arethe subcellular localisation of Hpa effectors in the hostcell and the identification of Hpa effector plant targets.The characterization of oomycete effectors that enter theplant cell, their functions and protein-uptake mechanismswill be a fascinating area for understanding the basis ofplant pathogenesis and will shed light on fundamentalcellular mechanisms in plants.