Amylase activity and growth in internodes of deepwater rice |
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Authors: | Mary A. Smith John V. Jacobsen Hans Kende |
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Affiliation: | (1) MSU-DOE Plant Research Laboratory, Michigan State University, 48824 East Lansing, MI, USA;(2) Present address: Division of Plant Industry, CSIRO, 2601 Canberra, A.C.T., Australia |
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Abstract: | Isoelectrofocusing, product analysis, thermal denaturation studies and affinity chromatography on cycloheptaamylose-Sephadex were used to identify the amylolytic enzymes in internodes of deepwater rice (Oryza sativa L.). Amylolytic activity in internodes of deepwater rice consists of -amylase (sometimes separated into two isoforms) and of -amylase. During submergence of whole plants, -amylase activity increases in young, growing internodes, but -amylase activity declines. Although non-growing, mature internodes contain higher levels of -amylase than do the elongating younger internodes, the effect of submergence on amylase activities in both tissues follows the same trend. Submergence, gibberellic acid (GA3) and ethylene all promote -amylase activity in growing and non-growing internodes of excised deepwater-rice stem sections. Inhibitor studies showed that submergence and ethylene promote -amylase activity in the absence of endogenous gibberellin (GA), and GA3 enhances -amylase activity when ethylene action is inhibited. Therefore, ethylene and GA appear to increase -amylase activity independently of each other. Enhanced -amylase activities are probably responsible for the mobilization of carbohydrates which are needed to support internode elongation during submergence of deepwater rice.Abbreviations CHA cycloheptaamylose - GA3 gibberellic acid - NBD 2,5-norbornadiene - TCY tetcyclacis |
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Keywords: | Amylase Deepwater rice Ethylene and internode growth Gibberellin and internode growth Internode growth Oryza (amylases and growth) |
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