Autolysis of cell walls in pea epicotyls during growth. Enzymatic activities involved

Abstract

Pisum sativum L. (cv. Lincoln) epicotyl cell walls show autohydrolysis and release into the incubation medium up to 120 μg of sugar per mg of cell wall dry weight in 30 h. Cell walls from younger epicotyls with high growth capacity showed higher auto‐lytic capacity than older epicotyls. This suggests that both processes, growth and au‐tolysis, are related. The proteins responsible for autolysis were extracted from the wall fraction with high saline solution (3 M LiCl) and enzymatic activities associated with the proteins were studied. The highest activity corresponded to α‐galactosidase; lower activities were found for β‐galactosidase, a‐arabinosidase and exoglucanase. Changes in enzymatic activities and changes in the proportion of sugars released in autolysis by cell walls during the growth of epicotyls support the notion that α‐galac‐tosidase is one of the enzymes involved in the process of autolysis, and that the liberation of arabinose and galactose in this process occurs as arabinogalactan.