Role of T3S in A. citrulli colonization of watermelon seed
during germination. Both AAC00-1ΔhrcC and AAC00-
1ΔhrcCcomp colonized watermelon seed at wild-type levels during
the first 96 h of germination. For all strains, populations increased
on watermelon seed by 6 h after planting (Fig. 3A). AAC00-
1ΔhrcC and AAC00-1ΔhrcCcomp increased continuously over the
course of the experiment (96 h), similar to AAC00-1. By 96 h after
planting, the mean populations of AAC00-1, AAC00-1ΔhrcC, and
AAC00-1ΔhrcCcomp were 1.7 × 109, 3.9 × 108, and 1.6 × 109
CFU/g of seed, respectively (Fig. 3A). For seed inoculated with
AAC00-1 and AAC00-1ΔhrcCcomp, seedlings emerged and developed
typical BFB symptoms on cotyledons by 14 days after planting
(dap). In contrast, seedlings from seed inoculated with AAC00-
1ΔhrcC emerged and remained asymptomatic by 14 dap. ANOVA
conducted on AUPDC data indicated that the effect of experiment
was not statistically significant (P = 0.94); therefore, data from
three experiments were pooled and analyzed. There was no significant
difference in the colonization of watermelon seed by AAC00-
1ΔhrcC, AAC00-1, and AAC00-1ΔhrcCcomp according to Tukey-
Kramer’s HSD (P = 0.19; Fig. 3B)