Evidence of multiple circadian oscillators in bean plants.
Circadian rhythms in stomatal opening and photosynthesis had shorter free-running periods than circadian rhythms in leaflet movement in bean plants (Phaseolus vulgaris L.) transferred from 12-hr photoperiods to constant conditions. The rhythm in leaflet movement had a period close to 27 hr, whereas the rhythm in stomatal opening, measured as conductance to water vapor, had a period close to 24 hr. Photosynthesis, measured as net assimilation of CO2, also oscillated with a period close to 24 hr. The periods of these rhythms did not vary with increasing temperature, demonstrating temperature compensation of the controlling oscillators. The difference in free-running periods displayed by these rhythms is evidence that multiple oscillators with different intrinsic frequencies operate in bean plants.
Hennessey
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TL
Carnegie Institution, Washington Department of Plant Biology, Stanford, California 94305.
Field
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CB
D001683:Biological Clocks / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D007887:Fabaceae / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology; D010946:Plants, Medicinal