Effects of gibberellic acid (GA) on degree of esterification (DE%) in WT (L er ), ga1-3 and gai hypocotyl cell walls. (A) Hypocotyl length at time of excision in 3-d-old seedlings. Measurements are an average of 40 to 90 hypocotyls ± SE for each genotype and treatment. (B) Uronic acid content and methyl ester content (measured as methanol) in walls of hypocotyls in (A). Each assay was performed on 50 to 100 hypocotyls for each genotype/treatment and repeated at least once in each experiment. Each experiment was performed three times. Amount of uronic acid and methanol was converted to nmol per hypocotyl in each replicate assay and the total values pooled. Measurements are the average of 6 to 9 replicates ± SE for each genotype and treatment. (C) Degree of methyl-esterification (DE%) in walls of hypocotyls in (A). Values in (B) (including SE) were ratioed (methanol to uronic acid) to give DE%.