Subcellular localization of the Hpa RxLR effector repertoire Identifies a tonoplast-associated protein HaRxL17 that confers enhanced plant susceptibility.

MARIE-CECILE CAILLAUD; SOPHIE J. M. PIQUEREZ; GEORGINA FABRO; JENS STEINBRENNER; NAVEED ISHAQUE; JIM BEYNON; JONATHAN D. G. JONES

PLANT JOURNAL

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Malden; Año: 2012 vol. 69 p. 252 - 265

0960-7412

Filamentous phytopathogens form sophisticated intracellular feeding structures called haustoria in plant cells.Pathogen effectors are likely to play a role in the establishment and maintenance of haustoria in addition totheir better-characterized role in suppressing plant defence. However, the specific mechanisms by whichthese effectors promote virulence remain unclear. To address this question, we examined changes insubcellular architecture using live-cell imaging during the compatible interaction between the oomyceteHyaloperonospora arabidopsidis (Hpa) and its host Arabidopsis. We monitored host-cell restructuring ofsubcellular compartments within plant mesophyll cells during haustoria ontogenesis. Live-cell imaginghighlighted rearrangements in plant cell membranes upon infection, in particular to the tonoplast, which waslocated close to the extra-haustorial membrane surrounding the haustorium. We also investigated thesubcellular localization patterns of Hpa RxLR effector candidates (HaRxLs) in planta. We identified two majorclasses of HaRxL effector based on localization: nuclear-localized effectors and membrane-localized effectors.Further, we identified a single effector, HaRxL17, that associated with the tonoplast in uninfected cells andwith membranes around haustoria, probably the extra-haustorial membrane, in infected cells. Functionalanalysis of selected effector candidates in planta revealed that HaRxL17 enhances plant susceptibility. Theroles of subcellular changes and effector localization, with specific reference to the potential role of HaRxL17 inplant cell membrane trafficking, are discussed with respect to Hpa virulence.