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KMID : 0368420070500040480
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Journal of Plant Biology
2007 Volume.50 No. 4 p.480 ~ p.483
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Effects of light on ultradian rhythms in the lateral leaflets ofDesmodium gyrans
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Miah Mohammad Idrish
Johnsson Anders
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Abstract
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Rhythmic up-down movements were studied in the lateral leaflets ofDesmodium gyrans (L.F.) DC. These were recorded with a video-computer system, whereby the digital video signals from a CCD camera were processed with special software. Under control conditions (24°C and 0.1 nM cm-2 s-1 of stable, dim light), the average period of lateral leaflet movement was 3.5 min. In the presence of light stimuli (for 2 min), those leaflets always moved toward the light, regardless of where it was applied to any axial part of the pulvinus. The strongest effect was manifested by a reduced amplitude of movement and, thus, a shortened period, which could be up to ~43% less under moderate light intensity (5 nM cm-2 s-2). Oscillations regained their original regularity over ~10 cycles after the light stimulus was removed. In addition, these oscillations temporarily disappeared after long exposure (~10 min) under moderate light, or when the leaflets were quickly exposed to a higher intensity (~12 nM cm-2s-1). Therefore, we have now demonstrated that light can affect physiological parameters that are involved in the control of oscillations.
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KEYWORD
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Desmodium gyrans, lateral leaflet, light stimulus, oscillation, pulvinus
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