FIGURE 6.

Overexpression of constitutively active (CA) StMPK7 triggers an SGT1/RAR1‐dependent cell death in Nicotiana benthamiana leaves. (a) Cell death triggered by CA‐StMPK7‐myc in leaves of N. benthamiana. The number next to the infiltrated zone indicates the OD₆₀₀ of the agrobacterial suspension used for agroinfiltration. (b) Cell death triggered by CA‐StMPK7‐myc is visible as dark spots in the leaves from which the chlorophyll was removed by treatment with ethanol. (c) 3,3′‐diaminobenzidine (DAB) staining revealing reactive oxygen species accumulation at the CA‐StMPK7‐myc‐infiltrated sites. (d) SGT1 and RAR1 are required for CA‐StMPK7‐myc‐triggered cell death. Three weeks after inoculation to initiate virus‐induced silencing of SGT1 or RAR1, the negative control GUS‐myc, the cell death inducer INF1, and CA‐StMPK7‐myc were agroinfiltrated at an OD₆₀₀ of 1.0 into the middle leaves of silenced plants. Pictures were taken at 5 days postinfiltration (dpi). The ratios next to the infiltrated zones show the number of infiltration sites showing cell death versus the total amount of infiltrated sites from two independent experiments at 5 dpi