Figure 4

Determination of disease resistance of ProA-Xa21 plants silenced for XIK1. Six week-old plants were inoculated with the Xoo strain PXO99A. The ProA-Xa21 and Kitaake (Kit) were used as resistant and susceptible controls, respectively. Photograph depicts the representative leaves from plants at 14 DPI. The leaves from Kitaake displayed the full susceptibility to Xoo (A) whereas the leaves from ProA-Xa21 displayed full resistance to Xoo (B). The panels C, D, and E show the representative leaves from the three transgenic lines, XXIK1Ri-1, XXIK1Ri-3 and XXIK1Ri-8, respectively. All photographs were taken at 14 DPI. Bars= 5cm. (F), Lesion lengths of XXIK1Ri after inoculation with Xoo. Lesion length was measured at 14 DPI. Graph shows average lesion length ± SD of at least 20 leaves from 10 independent plants homozygous for both Xa21 and XIK1Ri. The letters indicate significant differences (P<0.05) as determined by a one-way ANOVA followed by post hoc Tukey HSD analysis. (G), Bacterial cell numbers accumulated in ProA-Xa21 plants silenced for XIK1 after inoculation with Xoo. Bacterial cell numbers were counted at day 0, 7, 14, 21 post inoculations. Each data point represents the average ± SD of six leaves from two independent plants. The ** indicate significant differences (P<0.05) as determined by a one-way ANOVA followed by post hoc Tukey HSD analysis. These experiments were repeated at least three times with similar results.