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Identification of Gibberellins in Spinach and Effects of Light and Darkness on their Levels

Identification of Gibberellins in Spinach and Effects of Light and Darkness on their Levels Abstract The endogenous gibberellin (GA) content of spinach (Spinacia oleracea) was reinvestigated by combined gas chromatography-mass spectrometry analysis. The 13-hydroxy GAs: GA53, GA44, GA19, GA17, GA20, GA5, GA1, GA29, and GA8; the non-3, 13-hydroxy GAs: GA12, GA15, GA9, and GA51; and the 3β-hydroxy GAs: GA4, GA7, and GA34, were identified in spinach extracts by comparing full-scan mass spectra and Kovats retention indices with those of reference GAs. In addition, spinach plants contained GA7-isolactone, 16,17-dihydro-17-hydroxy-GA53, GA29-catabolite, 3-epi-GA1, and 10 uncharacterized GAs with mass spectra indicative of mono- and dihydroxy-GA12, monohydroxy-GA25, dihydroxy-GA24, and dihydroxy-GAg. The effect of light-dark conditions on the GA levels of the 13-hydroxylation pathway was studied by using labeled internal standards in selected ion monitoring mode. In short day, the GA levels were higher at the end of the light period than at the end of the dark period. Levels of GAs at the end of each short day were relatively constant. During the first supplementary light period of long day treatment, GA53 and GA19 declined dramatically, GA44 and GA1 decreased slightly, and GA20 increased. During the subsequent high-intensity light period, the GA20 level decreased and the levels of GA53, GA44, GA19, and GA1 increased slightly. Within 7 days after the beginning of long day treatment, similar patterns for GA53 and GA19 occurred. Furthermore, when these plants were transferred to darkness, an increase in the levels of GA53 and GA19 was observed. These results are compatible with the idea that in spinach, the flow through the GA biosynthetic pathway is much enhanced during the high-intensity light period, although GA turnover occurs also during the supplementary period of long day, both effects being responsible for the increase of GA20 and GA1 in long day. 1 Supported, in part, by a fellowship from the Spanish Ministry of Agriculture (Instituto Nacional de Investigaciones Agrarias) to M.T., and by the U.S. Department of Energy under contract DE-ACO2-76ERO-1338, and by U.S. Department of Agriculture grant No. 88-37261-3434 to J.A.D.Z. This content is only available as a PDF. © 1991 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Physiology Oxford University Press

Identification of Gibberellins in Spinach and Effects of Light and Darkness on their Levels

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References (24)

Publisher
Oxford University Press
Copyright
Copyright © 2021 American Society of Plant Biologists
ISSN
0032-0889
eISSN
1532-2548
DOI
10.1104/pp.97.4.1521
Publisher site
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Abstract

Abstract The endogenous gibberellin (GA) content of spinach (Spinacia oleracea) was reinvestigated by combined gas chromatography-mass spectrometry analysis. The 13-hydroxy GAs: GA53, GA44, GA19, GA17, GA20, GA5, GA1, GA29, and GA8; the non-3, 13-hydroxy GAs: GA12, GA15, GA9, and GA51; and the 3β-hydroxy GAs: GA4, GA7, and GA34, were identified in spinach extracts by comparing full-scan mass spectra and Kovats retention indices with those of reference GAs. In addition, spinach plants contained GA7-isolactone, 16,17-dihydro-17-hydroxy-GA53, GA29-catabolite, 3-epi-GA1, and 10 uncharacterized GAs with mass spectra indicative of mono- and dihydroxy-GA12, monohydroxy-GA25, dihydroxy-GA24, and dihydroxy-GAg. The effect of light-dark conditions on the GA levels of the 13-hydroxylation pathway was studied by using labeled internal standards in selected ion monitoring mode. In short day, the GA levels were higher at the end of the light period than at the end of the dark period. Levels of GAs at the end of each short day were relatively constant. During the first supplementary light period of long day treatment, GA53 and GA19 declined dramatically, GA44 and GA1 decreased slightly, and GA20 increased. During the subsequent high-intensity light period, the GA20 level decreased and the levels of GA53, GA44, GA19, and GA1 increased slightly. Within 7 days after the beginning of long day treatment, similar patterns for GA53 and GA19 occurred. Furthermore, when these plants were transferred to darkness, an increase in the levels of GA53 and GA19 was observed. These results are compatible with the idea that in spinach, the flow through the GA biosynthetic pathway is much enhanced during the high-intensity light period, although GA turnover occurs also during the supplementary period of long day, both effects being responsible for the increase of GA20 and GA1 in long day. 1 Supported, in part, by a fellowship from the Spanish Ministry of Agriculture (Instituto Nacional de Investigaciones Agrarias) to M.T., and by the U.S. Department of Energy under contract DE-ACO2-76ERO-1338, and by U.S. Department of Agriculture grant No. 88-37261-3434 to J.A.D.Z. This content is only available as a PDF. © 1991 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

Plant Physiology – Oxford University Press

Published: Dec 1, 1991

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