Protease inhibitors decrease the resistance of Vitaceae to Plasmopara viticola.
Plasmopara viticola must successfully infect susceptible grapevine cultivars to complete its biological cycle. In resistant grapevine varieties, P. viticola is blocked by the activation of defense mechanisms; these defense mechanisms produce hypersensitive reactions, which are related to programmed cell death. In animals, programmed cell death is dependent on caspase activities. In plants, different caspase-like proteases assume the same functions. To examine the roles of caspase-like proteases in P. viticola-grapevine interactions, three varieties of grapevine with different levels of P. viticola resistance were chosen. These grapevine varieties were treated with either PMSF, a serine protease inhibitor, or E-64, a cysteine protease inhibitor. The development of the pathogen was followed microscopically, and the plant defense reactions were estimated through stilbene quantification. Both protease inhibitor treatments increased the infection rate in the resistant and immune varieties, diminished the production of toxic stilbenes and changed the level of the plants' susceptibility to the pathogen. In particular, after either protease treatment, the cultivar that was originally immune became resistant (hyphae and haustoria were observed), the resistant cultivar reached the level of a susceptible cultivar (sporulation was observed) and the susceptible cultivar became more sensitive (P. viticola colonized the entirety of the leaf mesophyll).
Swiss Federal Research Station Agroscope Changins-Wädenswil, Route de Duillier, P.O. Box 1012, CH-1260 Nyon, Switzerland. katia.gindro@acw.admin.ch
Katia
K
Gindro
Valentine
V
Berger
Sophie
S
Godard
Francine
F
Voinesco
Sylvain
S
Schnee
Olivier
O
Viret
Virginia
V
Alonso-Villaverde
D000818:Animals; D017209:Apoptosis; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D060467:Disease Resistance / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006790:Host-Parasite Interactions; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009868:Oomycetes / Q000502:physiology*; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D010935:Plant Diseases / Q000276:immunology* / Q000469:parasitology; D018515:Plant Leaves / Q000187:drug effects / Q000276:immunology / Q000469:parasitology / Q000648:ultrastructure; D054046:Plant Stomata / Q000187:drug effects / Q000276:immunology / Q000469:parasitology / Q000648:ultrastructure; D011480:Protease Inhibitors / Q000494:pharmacology*; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D013267:Stilbenes / Q000032:analysis / Q000378:metabolism*; D027844:Vitaceae / Q000187:drug effects* / Q000276:immunology / Q000469:parasitology / Q000648:ultrastructure
D015853:Cysteine Proteinase Inhibitors; D011480:Protease Inhibitors; D015842:Serine Proteinase Inhibitors; D013267:Stilbenes; D010664:Phenylmethylsulfonyl Fluoride; D007930:Leucine; C024974:E 64