Involvement of a neutral proteolytic activity in the senescence of unpollinated ovaries of Pisum sativum>

Carrasco, P. and Carbonell, J. 1988. Involvement of a neutral proteolytic activity in the senescence of unpollinated ovaries of Pisum sativum. ‐ Physiol. Plant. 72: 610–616. The study of proteolysis by autodigestion in extracts from developing (gibberellic acid‐treated) or senescing (non‐treated) unpollinated ovaries of Pisum sativum L. cv. Alaska indicated the presence of two main proteolytic activities sensitive to inhibitors of sulfhydryl proteases. One of them was active at acidic pH and was present both in developing and senescent ovaries. The other one, active at neutral pH, was only detected in non‐treated ovaries and was identified by the hydrolysis of the large subunit of ribulose‐l,5‐bisphosphate (RuBP) carboxylase (EC 4.1.1.39). Senescence of non‐treated ovaries was also associated with an increase in proteolytic activity measured with a Coomassie Blue reagent and by determination with ninhydrin of a‐NH2 groups released after autodigestion of the extracts. The presence of the neutral proteolytic activity only in senescing ovaries, but not in developing ones, suggests that it plays a key role in the senescence of pea ovaries and that its appearance is prevented by gibberellic acid.