Gibberellin-enhanced Growth and Sugar Accumulation in Growing Subhooks of Etiolated Pisum sativum Seedlings: Effects of Actinomycin D on Invertase Activity, Soluble Sugars and Stem Elongation

The possible involvement of soluble acid invertase in the action of gibberellic acid (GA) in stimulating sugar accumulation in relation to osmoregulation and growth was studied in growing subhooks of etiolated Alaska pea (Pisum sativum L. cv. Alaska). GA enhanced elongation growth, soluble sugar accumulation and invertase activity, which appears to be involved in phloem unloading, in the growing subhook. Actinomycin 0 inhibited the effects ofGA on invertase activity, accumulation of soluble sugars and elongation growth. Positive correlations were found between invertase activity, the amount of soluble sugars and elongation growth. These results suggest that GA-induced synthesis of mRNA seems to be involved in the enhancement of invertase activity which is responsible for sugar translocation from the phloem to the growing cells of the stem.