Figure 2.

Time of infection during the day affects the requirement of MeSA for SAR development. The 1° and 2° infections of 3- to 4-week-old wild-type (wt) and bsmt1 mutant plants were done in the morning (A; 9:00–9:30 am) or late afternoon (B; 5:30–6:00 pm). Growth of Pst at 2 to 3 d post 2° inoculation from plants previously mock inoculated with MgCl₂ (black bars) or infected with Psm AvrRpt2 cor⁻ (SAR induction; white bars) is presented. All experiments were done at least twice with similar results; means of three replicates ± sd are presented. Asterisks directly above each set of white/black bars indicate statistically significant differences (** P < 0.01, Student’s t test) between Pst growth in plants induced for SAR by Psm AvrRpt2 cor⁻ versus growth in mock-inoculated controls. Letters within the white bars indicate whether there was a statistically significant difference (P < 0.05) in Pst growth in Psm AvrRpt2 cor⁻-inoculated wild-type and bsmt1-3 plants that were subjected to different times (am and pm) of inoculation, using ANOVA and posthoc tests. Bars with the same letter indicate no significant difference, while bars with different letters indicate significantly different levels of Pst growth.