Arabidopsis (Arabidopsis thaliana L. Heynh.) ecotype Col-0, Ler, and MPK3 guard cell-specific antisense line (Gudesblat et al., 2007) seeds were surface sterilized in 10% (v/v) commercial bleach with 0.01% (v/v) Tween 20 for 10 min and rinsed four times in sterile water. Seeds were plated in petri dishes containing one-half-strength Murashige and Skoog medium with 1% (w/v) Suc and 0.6% (w/v) agar. Seeds on plates were maintained in the dark for 2 to 3 d at 4°C to break dormancy before being transferred to a growth room at 22°C to 23°C, with a 12-h light photoperiod under light intensity of 90 μE m⁻² s⁻¹. After 5 or 6 d, seedlings were transferred to pots containing a mixture of vermiculite, peat, and perlite (1:1:1) and fertilized every 2 d. Vicia faba plants were grown in soil inside a growth room at 22°C to 23°C, with a 16-h light photoperiod.