Figure 9.

The necrosis-inducing activity of MBcXYG1 is not linked to plant defense-stimulating activity. A, One of the first two true leaves of 9-d-old bean seedlings was infiltrated with 500 μL of the indicated proteins at 100 μg mL⁻¹. After 2 d, the other leaf was inoculated with B. cinerea, the plants were incubated in a humid chamber, and the lesions were photographed and measured 72 hpi. Blank control, Untreated first leaf; BcXYG2, pretreatment with BcXYG2; MBcXYG1, enzyme-inactive BcXYG1 protein; Mutant^{118-120 157-161}, enzyme- and necrosis-inactive BcXYG1 protein in which the external loops 118 to 120 and 157 to 161 were mutated (MBcXYG1^{GSN118-120AAA SETGS157-161AAAAA}). Data represent means and sd from three independent experiments, each with six replications. Different letters in the graph indicate statistical differences at P ≤ 0.01 using one-way ANOVA. B, Relative expression of defense genes. RNA was extracted from the untreated leaf 48 h after treatment of the first leaf, and the levels of the defense genes Pvd1, PvPR1, and PvPR2 were determined by qRT-PCR. Expression in blank control plants was set as 1. The expression level of the bean Actin-11 gene was used to normalize different samples. Data represent means and sd of three independent replicates.