No Significant MPK6 Activation Was Observed in Arabidopsis Seedlings Treated with ACC.(A) Two-week-old wild-type and mutant seedlings grown in 50-mL GC vials were treated with ACC (1 mM final concentration). No Significant MPK6 Activation Was Observed in Arabidopsis Seedlings Treated with ACC.(A) Two-week-old wild-type and mutant seedlings grown in 50-mL GC vials were treated with ACC (1 mM final concentration). The pH of ACC stock solutions was either adjusted to 5.8 or unadjusted. Samples were taken before the addition of ACC (0 min) and 10 and 30 min after the addition of ACC. Wounding treated samples were used as positive controls. MAPK activity in the total protein extracts was determined by in-gel kinase assay using MBP as a substrate.(B) Ethylene production in Arabidopsis seedlings in the absence and presence of exogenous ACC. Two-week-old Arabidopsis seedlings grown in 50-mL GC vials were treated with 1 mM ACC (+) or an equal volume of water (−) as controls. The vials were flushed and then capped. Ethylene levels in the headspace were determined after 1 h for vials received ACC or after 24 h for vials received no ACC. Error bars indicate standard deviation (n = 3). Yidong Liu, and Shuqun Zhang Plant Cell 2004;16:3386-3399 ©2004 by American Society of Plant Biologists