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Type: Artigo de periódico
Title: The Utilization Of Cotyledonary Reserves In Phaseolus Vulgaris L. Cv. Carioca: I. Changes In Total Amylolytic And Proteolytic Activity And The Effects Of 6-benzyladenine And Gibberellic Acid Upon Whole Seedlings
Author: Metivier J.
Paulilo M.T.
Abstract: Axis growth commenced only 20 h from imbibition in Phaseolus vulgaris when both uptake of water and oxygen were levelling off. Cotyledonary dry material was exhausted by day 9, the greatest rates of transfer occurring from day 2. Utilization of reserve protein proceeded relatively faster than dry matter and proportionately more was translocated to the shoot, particularly the leaf blades. Lamina protein and chlorophyll content showed a biphasic increase with rapid synthesis prior to day 7 being followed by slower rates up to maximum leaf area on day 17. The level of free amino acids in the cotyledons fell continuously from day 3 and rose to peak levels in the axis between days 5 and 7. Soluble sugars increased throughout the period examined in the axis and accumulated in the cotyledons prior to day 7.Exogenous application of GA 3 had marked morphological effects upon the seedling though did not significantly alter the distribution of dry matter or protein reserves: 6-BA, in addition to distinct morphological effects, delayed the mobilization of reserves to the axis.Total amylolytic activity in the cotyledon, optimal at pH 5.5, increased continually from day 3 to 9 whereupon activity abruptly declined. This increase was due to the appearance of α-amylase; β-amylase, while present, remained at a constant and comparatively low level. Peak proteolytic activity occurred prior to that for amylases between days 5 and 7. 6-BA significantly increased both amylolytic and proteolytic activities in vitro though did not alter the changes in levels of free amino acids or sugars in the reserve tissue and axis. The discrepancy between in vivo and in vitro effects of 6-BA may be attributed to concomitant effects upon seedling development whereby sink capacity is reduced. © 1980 Oxford University Press.
Rights: fechado
Identifier DOI: 10.1093/jxb/31.5.1257
Date Issue: 1980
Appears in Collections:Unicamp - Artigos e Outros Documentos

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