Figure 5

Mutant ocp3-1 plants are not able to mount ISR against P. syringae and H. arabidopsidis. (a) Quantification of P. fluorescens WCS417r-mediated ISR against Pst DC3000 in Arabidopsis Col-0 and ocp3-1 plants. The level of induced protection calculated on the basis of the reduction in disease symptoms relative to challenged, non-induced plants. Asterisks indicate statistically significant levels of protection compared to non-induced control plants (Students t-test: α = 0.05; n = 20 plants). Data presented are means from two independent experiments. Error bars represents standard errors. (b) Quantification of colonization and sporulation of H. arabidopsidis infected plants (From class I = no colonization/sporulation to class IV = high colonization/sporulation). Asterisks indicate statistically significant distributions of the disease severity classes compared to noninduced control treatments (Chi-square, P < 0.05; n = 200 leaves). The data presented are from a representative experiment that was repeated with similar results. (c) Lactophenol trypan-blue stained control- and P. fluorescens WCS417r-treated Col-0 and ocp3-1 plants 7 days after inoculation with H. arabidopsidis. Pst DC3000 inoculation experiments were repeated three times and twice for H. arabidopsidis always with a similar out come.