then was resuspended at 0.1 g ml21 fresh weight of cells. After 1 h of equilibration, grapevine cells were treated with b-glucans and analyses of ROS production, cytosolic Ca2+ concentration variations, or MAPK phosphorylation were performed. Free Cytosolic Calcium Concentration Variation Analysis Measurements of the cyt were based on aequorin bioluminescence using a luminometer. In vivo reconstitution of aequorin was performed by the addition of 6 ml of coelenterazine to 10 ml of aequorin-transformed cell suspension for at least 3 h in the dark. Luminescence was recorded continuously and data converted to free cytosolic calcium concentration using the calibration equation described in Vandelle et al.. H2O2 Production Measurement H2O2 production was assessed using a luminol chemiluminescence assay with a luminometer. Aliquots of cell suspension were analyzed after the addition of 300 ml of H50 medium and 50 ml of 0.3 mM luminol. PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19645596 Luminescence emission was monitored and recorded every 10 s. Relative luminescence units were converted in nmol of H2O2 per gram of fresh weight cell, after the establishment of a H2O2 reference range with untreated cell suspension. Beta-Glucan IR in Grapevine against Downy Mildew Plasma Membrane Depolarization Measurement Cells were equilibrated in the dark for 2 h in suspension buffer supplemented with 10 mM DiBAC4 trimethine), as described in Dubreuil-Maurizi et al.. Five hundred microliters were transferred per well into a C.I. Natural Yellow 1 24-well plate and DiBAC4 fluorescence was recorded continuously at 10s intervals, using a fluorimeter with lex = 485 nm and lem = 525 nm. Fluorescence was expressed as relative fluorescence units. Localization of H2O2 and Callose Deposition in Treated Leaves In situ H2O2 production was revealed by brown precipitates after 3,39-diaminobenzidine staining. Gli, DPI, or DMSO was administered by petiolar absorption during 24 h, and then 2nd and 3rd fully expanded leaves were transferred into water. Leaves were sprayed with adjuvant or PS3 until the runoff point and inoculated 1 day later with P. viticola to upper and lower leaf faces. Leaves were harvested at different time points and transferred for an additional 5 h period to DAB solution. Harvested leaf discs were bleached first with pure methanol, then chloral hydrate solution. H2O2 is visualized as a reddish-brown deposit in DAB-treated leaves. Callose deposition was revealed by aniline blue staining as previously described. Briefly, clarified leaf disks were stained in 0.05% aniline blue overnight and then were mounted on microscope slides in the same solution. Pathogen structure and callose deposition were observed in blue by epifluorescence microscopy under UV. Western Blot Analyses Fifteen mg of protein per sample were solubilized in Laemmli buffer, submitted to 12% SDS-PAGE before Western blotting. Nitrocellulose membrane is pre-incubated first during 2 h at room temperature with TBST buffer and 1% BSA; then incubated with primary antibody: anti non phosphorylated human ERK1/2 or anti-phospho Thr202/Tyr204 peptide of human ERK1/2 mouse antibody, 1/3000 diluted in TBST buffer during 1h30 under shaking. After 3 washes with TBST buffer for 10 min each time, membrane is 
incubated with goat HRPconjugated anti-mouse secondary antibody, 1/ 6000 diluted in TBST buffer. After 3 washes with TBST buffer for 10 min each time, MAPK were detected using ECL detection kit. Microarray Analysis Triplicate samples were collected on grapevine plants spr
