Subcellular Localization of the Hpa RxLR Effector Repertoire Identifies the Extrahaustorial Membrane-Localized 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: 2011 p. 1 - 5

0960-7412

Filamentous phytopathogens form sophisticated intracellular feeding structures calledhaustoria in plant cells. Pathogen effectors are likely to play a role in theestablishment and maintenance of haustoria additional to their more characterised roleof suppressing plant defence. However, the specific mechanisms by which theseeffectors promote virulence remain unclear. To address this question we examinedchanges to subcellular architecture by live-cell imaging during the compatibleinteraction between the oomycete Hyaloperonospora arabidopsidis (Hpa) and its hostArabidopsis. We monitored host cell restructuring of subcellular compartments withinplant mesophyll cells during haustoria ontogenesis. Live-cell imaging highlightedrearrangements in plant cell membranes upon infection, in particular to the tonoplastwhich appeared close to the extrahaustorial membrane surrounding the haustorium.We also investigated the subcellular localization patterns of Hpa RxLR effectorcandidates (HaRxLs) in planta. We identified two major classes of HaRxL effectorlocalization: nuclear-localized effectors and membrane-localized effectors. Further,we identified a single effector, HaRxL17, which associated with the tonoplast inuninfected cells and with membranes around haustoria, likely the EHM, in infectedcells. Functional analysis of selected effector candidates in planta revealed thatHaRxL17 enhances plant susceptibility. The role of subcellular changes and effectorlocalizations, with specific reference to the potential role of HaRxL17 in plant cellmembrane trafficking, is discussed with respect to Hpa virulence.