Production of Cell Wall Hydrolyzing Enzymes by Barley Aleurone Layers in Response to Gibberellic Acid

The cell walls of barley (Hordeum vulgare var. Himalaya) aleurone layers undergo extensive degradation during the tissue's response to gibberellic acid. Previous work had shown that these cell walls consist almost entirely of arabinoxylan. In this study we show that gibberellic acid stimulates endo-beta-1,4-xylanase activity in isolated aleurone layers. In addition, gibberellic acid enhances the activity of two glycosidases: beta-xylopyranosidase and alpha-arabinofuranosidase. No gibberellic acid-stimulated cellulase activity was detected. Germination studies showed a similar pattern of enzyme development in intact seeds.