Gibberellin induces endopeptidase activity in detached cotyledons of Pisum sativum

Endopeptidase activity in cotyledons of 5-day seedlings of Pisum sativum increased rapidly during germination. However, the increase of the activity in detached cotyledons was depressed. We examined whether a growth regulator can be substituted for the embryonic axis on the development of endopeptidase activity. As monitored by an assay with azoalbumin, the development of endopeptidase activity from crude extracts of detached cotyledons appeared to be slightly accelerated by incubation with 10^–5 M GA₃. However, the pattern after gelatin-polyacrylamide gel suggested that the activity induced in detached cotyledons during a 5-d incubation at 10^–7 M GA₃ was the same as that in attached ones during germination for 5 days and an even greater increase in activity was obtained with 10^–5 M GA₃. These results suggest that GA₃ from the embryonic axis induces endopeptidase activity in attached cotyledons at the first stage of germination.Abbreviations ABA abscisic acid - IAA indole-3-acetic acid - GA gibberellic acid