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Abstract Background Investigations into the diurnal ascent and descent of leaves of beans and other species, as well as experimental interventions into these movements, such as exposures to light at different times during the movement cycle, led to the concept of an endogenous ‘clock’ as a regulator of these oscillations. The causal origin of leaf movement can be traced to processes that modulate cell volume in target tissues of the pulvinus and petiole. However, these elements of the leaf-movement process do not sufficiently account for the rhythms that are generated following germination in constant light or dark conditions, or when plants are transferred to similar free-running conditions. Scope To further unravel the regulation of leaf-movement rhythms, many of the published time courses of leaf movements that provided evidence for the concept of the endogenous clock were analysed in conjunction with the contemporaneous time courses of the lunisolar tidal acceleration. This was accomplished by application of the Etide program, which estimates, with high temporal resolution, local gravitational changes as a consequence of the diurnal variations of the lunisolar gravitational force due to the orbits and relative positions of Earth, Moon and Sun. To substantiate the results obtained in earthbound laboratories additional experiments were performed in the International Space Station (ISS). Tidal recurrence within the ISS exhibited a periodicity of 45 min. In all instances investigated, it was evident that a synchronism exists between the times of the turning points of both the lunisolar tide and of the leaftide when the direction of leaf movement changes. This finding of synchrony documents that the lunisolar tide is a regulator of the leaftide, and that the rhythm of leaf movement is not of endogenous origin but is an expression of an exogenous lunisolar clock impressed upon the leaf-movement apparatus. Conclusions A huge number of correlations between leaftide and Etide time courses were established for leaf movement rhythms in natural conditions of the greenhouse, in conditions of constant light or dark, and under the microgravity conditions of the International Space Station. Even the apparently spontaneous short-period, small-amplitude rhythms recorded from leaves under unusual growth conditions are consistent with the hypothesis of a lunisolar zeitgeber. Synchronism between leaftide and Etide is discussed in terms of classical and quantum mechanics. Biological clock, Canavalia ensiformis, circadian rhythm, coherence domain, gravitational force, leaf movements, lunisolar gravitational acceleration, Phaseolus coccineus, pulvinus, tidal acceleration, zeitgeber The Editor-in-Chief and Publisher have retracted this article due to concerns over re-use of text from previously published work. Our journal instructions state that ‘All work submitted to Annals of Botany should be novel, rigorous and substantial, and the Editors may make plagiarism checks at any time after submission’. [https://academic.oup.com/aob/pages/General_Instructions] In accordance with this policy, the paper was subjected to additional checks using anti-plagiarism software. These checks confirmed unusually high levels of similarity with previously published work. The level of overlap raises sufficient doubt over the originality of the work. The Editors wish to express their regret that these issues were not identified at an earlier stage. The Journal endeavours to ensure that all papers published are original and appear in compliance with ethical guidelines endorsed by the Committee for Publication Ethics. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices)
Annals of Botany – Oxford University Press
Published: Jan 24, 2018
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