Viral protein suppresses oxidative burst and salicylic acid-dependent autophagy and facilitates bacterial growth on virus-infected plants.
Virus interactions with plant silencing and innate immunity pathways can potentially alter the susceptibility of virus-infected plants to secondary infections with nonviral pathogens. We found that Arabidopsis plants infected with Cauliflower mosaic virus (CaMV) or transgenic for CaMV silencing suppressor P6 exhibit increased susceptibility to Pseudomonas syringae pv. tomato (Pst) and allow robust growth of the Pst mutant hrcC-, which cannot deploy effectors to suppress innate immunity. The impaired antibacterial defense correlated with the suppressed oxidative burst, reduced accumulation of the defense hormone salicylic acid (SA) and diminished SA-dependent autophagy. The viral protein domain required for suppression of these plant defense responses is dispensable for silencing suppression but essential for binding and activation of the plant target-of-rapamycin (TOR) kinase which, in its active state, blocks cellular autophagy and promotes CaMV translation. Our findings imply that CaMV P6 is a versatile viral effector suppressing both silencing and innate immunity. P6-mediated suppression of oxidative burst and SA-dependent autophagy may predispose CaMV-infected plants to bacterial infection.
Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, Basel, 4056, Switzerland.
Anna S
AS
Zvereva
Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, Basel, 4056, Switzerland.
Victor
V
Golyaev
Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, Basel, 4056, Switzerland.
Silvia
S
Turco
Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, Basel, 4056, Switzerland.
Ekaterina G
EG
Gubaeva
Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, Basel, 4056, Switzerland.
Rajendran
R
Rajeswaran
Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg Cedex, 67084, France.
Mikhail V
MV
Schepetilnikov
Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg Cedex, 67084, France.
Ola
O
Srour
Institut de Biologie Moléculaire des Plantes du CNRS, Université de Strasbourg, Strasbourg Cedex, 67084, France.
Lyubov A
LA
Ryabova
Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, Basel, 4056, Switzerland.
Thomas
T
Boller
Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, Basel, 4056, Switzerland.
Mikhail M
MM
Pooggin
D017360:Arabidopsis / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology / Q000821:virology*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001343:Autophagy / Q000187:drug effects*; D017796:Caulimovirus / Q000187:drug effects / Q000472:pathogenicity / Q000502:physiology*; D020868:Gene Silencing / Q000187:drug effects; D007113:Immunity, Innate / Q000187:drug effects; D010935:Plant Diseases / Q000382:microbiology / Q000821:virology; D000072417:Protein Domains; D044224:Pseudomonas syringae / Q000187:drug effects / Q000254:growth & development*; D016897:Respiratory Burst / Q000187:drug effects; D020156:Salicylic Acid / Q000494:pharmacology*; D017384:Sequence Deletion; D014764:Viral Proteins / Q000737:chemistry / Q000378:metabolism*
D029681:Arabidopsis Proteins; D014764:Viral Proteins; D020156:Salicylic Acid
Cauliflower mosaic virus; RNA silencing; autophagy; effector protein; innate immunity; oxidative burst; salicylic acid (SA); target-of-rapamycin