Development of (1-->3,1-->4)-beta-d-Glucan Endohydrolase Isoenzymes in Isolated Scutella and Aleurone Layers of Barley (Hordeum vulgare) |
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Authors: | Stuart I M Loi L Fincher G B |
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Institution: | Department of Biochemistry, La Trobe University, Bundoora, Victoria, 3083, Australia. |
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Abstract: | An immunological assay has been used to investigate the synthesis of (1→3,1→4)-β-glucanase (EC 3.2.1.73) isoenzymes from isolated barley aleurone layers and scutella. Enzyme release from both tissues is enhanced by 1 micromolar gibberellic acid and 10 millimolar Ca2+, although increases induced by gibberellic acid are observed only in the presence of Ca2+. Isoenzyme I is synthesized predominantly in the scutellum, while isoenzyme II is synthesized exclusively in the aleurone. A third, putative isoenzyme III has been detected in significant proportions in scutellar secretions and may also be secreted from aleurone layers. Both gibberellic acid and Ca2+ appear to preferentially enhance isoenzyme II secretion from the aleurone and isoenzyme III secretion from scutella. The patterns of isoenzyme secretion are suggestive of tissue-specific differences in expression of the genes which code for (1→3,1→4)-β-glucanase isoenzymes. Qualitatively similar results were obtained with barley cultivars harvested in Australia and North America. |
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