Fig. 8.

Pre-treatment or co-infiltration with DSF inhibits wild-type Xcc8004 growth in N. benthamiana leaves. (A) Leaves of 4-week-old plants were pre-infiltrated with either control buffer (black bars), EPS (xanthan; 0.5mg ml^–1), DSF (100 μM), or DSF+EPS (xanthan; 0.5mg ml^–1) by syringe infiltration 16h prior to inoculation with a 10⁷ cfu ml^–1 suspension of the wild-type Xcc8004 strain. Bacterial populations were measured at 0, 24, and 48h post-inoculation. Values presented are average log (cfu cm^–2) from six leaves (three leaves each from two independent experiments). * indicates (P≤0.05) a significantly lower bacterial population in the DSF-pre-inoculated leaves compared with the leaves inoculated with the wild-type Xcc8004 strain alone based on a pairwise Student’s t-test. (B) Bacterial growth assay in N. benthamiana leaves co-infiltrated with the Xcc8004 wild-type strain with either water control (black bars), DSF (100 μM), EPS (xanthan; 0.5mg ml^–1), or DSF+EPS (xanthan). The bacterial population was measured at 0, 8, 24, and 48h after inoculation. Values presented are average log (cfu ml^–1) from six leaves (three leaves each from two independent experiments). * indicates (P≤0.001) a significantly lower bacterial population in the DSF-co-inoculated leaves compared with the leaves inoculated with wild-type Xcc alone based on a pairwise Student’s t-test. (C) Photographs of representative leaves from the co-inoculation experiments 4 d post-inoculation. N. benthamiana leaves exhibit water soaking-like disease symptoms when inoculated with the Xcc8004 wild-type strain (shown in a dotted circle). Leaves co-inoculated with the Xcc8004 wild-type strain+DSF exhibited less vigorous water soaking symptoms compared with leaves treated with the Xcc8004 strain alone.