Figure 5.

Arabidopsis MPK3 and MPK6 play essential and overlapping roles in Pst-induced ethylene biosynthesis and SA potentiation. A, Twelve-day-old wild-type (Col-0), mpk3, and mpk6 seedlings grown in GC vials were treated with DMSO solvent (−SA) or SA (+SA; final concentration of 100 µm). Two days later, Pst was inoculated (final OD₆₀₀ = 0.02), and ethylene accumulation in the headspace of the GC vials was measured. B, Twelve-day-old wild-type (Col-0) and chemical genetically rescued mpk3 mpk6 double mutant (MPK6SR line 45) seedlings grown in GC vials were treated with SA (+SA; final concentration of 100 µm) or DMSO, the solvent of SA stock solution (−SA). Two days later, they were inoculated with Pst (final OD₆₀₀ = 0.02) after pretreatment with NA-PP1 (+NA-PP1; 5 µm final concentration) or solvent control (+DMSO) for 30 min. Ethylene accumulations in the headspace were determined at the indicated times. Error bars indicate sd (n = 3). Student’s t test was used to compare mutants and the wild type at the same time point after the same treatment (*, P ≤ 0.05; and **, P ≤ 0.01). FW, Fresh weight; hpi, hours post inoculation.