Figure 3.

Effect of leaf treatments on gene expression of grapevine plants under greenhouse conditions. Grapevine plants were left untreated (gray), treated daily with water (blue), nutrient broth (orange) or laminarin (green) three times before Plasmopara viticola inoculation. Leaf samples were collected just before (T0) and 1 day after (T1) pathogen inoculation. Relative expression levels of genes encoding the pathogenesis-related (PR) protein 1 (PR-1; A), PR-2 (B), PR-4 (C), chitinase 3 (CHIT-3; D), osmotin 1 (OSM-1; E), and OSM-2 (F) were assessed by quantitative real-time PCR. Relative expression levels were calculated using Actin as constitutive gene for normalization, and data were calibrated on untreated plants at T0. The F-test revealed differences between the experiments (P-values ranged from 0.0003 to 0.038 for the genes tested), and each experiment was analyzed separately for each gene. For each time point, mean levels and standard errors of relative expression are calculated based on three replicates (plants) for each treatment and experiment. For each gene, different uppercase and lowercase letters indicate significant differences among treatments and time points according to Fisher's test (α = 0.05) in experiment 1 (solid bars) and experiment 2 (striped bars), respectively.