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A comparison of the effects of Ca 2+ and gibberellic acid on enzyme synthesis and secretion in barley aleurone
Author(s) -
Carbonell Juan,
Jones Russell L.
Publication year - 1985
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1985.tb02308.x
Subject(s) - aleurone , gibberellic acid , hordeum vulgare , amylase , incubation , isozyme , enzyme , biochemistry , gibberellin , acid phosphatase , enzyme assay , biology , chemistry , botany , poaceae , germination
The effects of the addition and withdrawal of gibberellic acid (GA 3 ) and Ca 2+ on enzyme synthesis and secretion by barley ( Hordeum vulgare L. cv. Himalaya) aleurone layers were studied. Incubation of layers in GA 3 plus Ca 2+ affects the total amount of secreted α‐amylase (EC 3.2.1.1) and acid phosphatase (EC 3.1.3.2) by promoting the appearance of different isoenzymic forms of these enzymes. The release of α‐amylase isoenzymes 1–4 in response to GA 3 plus Ca 2+ has a lag of 6 h. When layers are incubated in GA 3 alone for 6 h prior to the addition of Ca 2+ , isoenzymes 1–4 appear in the medium after only 30 min. When the addition of Ca 2+ to layers pretreated in GA 3 is delayed beyond 12 h, its effectiveness in stimulating the synthesis and release of isoenzymes 3 and 4 is diminished. After 35 h of preincubation in GA 3 , addition of Ca 2+ will not stimulate synthesis of α‐amylase isoenzymes 3 and 4. Aleurone layers preincubated for 6 h in GA 3 will respond to Ca 2+ when the GA 3 is withdrawn from the incubation medium by producing α‐amylase isoenzymes 1–4. The converse is not the case, however, since layers preincubated in Ca 2+ for 6 h will not produce all isoenzymes of α‐amylase when subsequently incubated in GA 3 . The Ca 2+ ‐stimulated release of α‐amylase from GA 3 pre‐treated layers is dependent on the time of incubation in Ca 2+ and the concentration of the ion. The response to Ca 2+ is temperature‐dependent, and other divalent cations such as Mg 2+ cannot substitute for Ca 2+ . We conclude that Ca 2+ influences α‐amylase release by influencing events at the biochemical level.