The plasmodesmal protein PDLP1 localises to haustoria-associated membranes during downy mildew infection and regulates callose deposition.
The downy mildew pathogen Hyaloperonospora arabidopsidis (Hpa) is a filamentous oomycete that invades plant cells via sophisticated but poorly understood structures called haustoria. Haustoria are separated from the host cell cytoplasm and surrounded by an extrahaustorial membrane (EHM) of unknown origin. In some interactions, including Hpa-Arabidopsis, haustoria are progressively encased by host-derived, callose-rich materials but the molecular mechanisms by which callose accumulates around haustoria remain unclear. Here, we report that PLASMODESMATA-LOCATED PROTEIN 1 (PDLP1) is expressed at high levels in Hpa infected cells. Unlike other plasma membrane proteins, which are often excluded from the EHM, PDLP1 is located at the EHM in Hpa-infected cells prior to encasement. The transmembrane domain and cytoplasmic tail of PDLP1 are sufficient to convey this localization. PDLP1 also associates with the developing encasement but this association is lost when encasements are fully mature. We found that the pdlp1,2,3 triple mutant is more susceptible to Hpa while overexpression of PDLP1 enhances plant resistance, suggesting that PDLPs enhance basal immunity against Hpa. Haustorial encasements are depleted in callose in pdlp1,2,3 mutant plants whereas PDLP1 over-expression elevates callose deposition around haustoria and across the cell surface. These data indicate that PDLPs contribute to callose encasement of Hpa haustoria and suggests that the deposition of callose at haustoria may involve similar mechanisms to callose deposition at plasmodesmata.
The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom.
Marie-Cécile
MC
Caillaud
The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom; John Innes Centre, Norwich Research Park, Norwich, United Kingdom.
Lennart
L
Wirthmueller
The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom.
Jan
J
Sklenar
John Innes Centre, Norwich Research Park, Norwich, United Kingdom.
Kim
K
Findlay
The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom.
Sophie J M
SJ
Piquerez
The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom; School of Life Sciences, University of Warwick, Coventry, United Kingdom.
Alexandra M E
AM
Jones
The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom.
Silke
S
Robatzek
The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom.
Jonathan D G
JD
Jones
The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom; John Innes Centre, Norwich Research Park, Norwich, United Kingdom; Biological and Biomedical Sciences, Oxford Brookes University, Oxford, United Kingdom.
Christine
C
Faulkner
D017360:Arabidopsis / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005936:Glucans / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D047908:Intracellular Signaling Peptides and Proteins; D009154:Mutation; D009868:Oomycetes / Q000502:physiology*; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D030821:Plants, Genetically Modified; D031425:Plasmodesmata / Q000378:metabolism
D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D005936:Glucans; D047908:Intracellular Signaling Peptides and Proteins; C528450:PDLP1a protein, Arabidopsis; C048306:callose