Light-stimulated cell expansion in bean (Phaseolus vulgaris L.) leaves.  II.  Quantity and quality of light required.
The quantity and quality of light required for light-stimulated cell expansion in leaves of Phaseolus vulgaris L. have been determined.  Seedlings were grown in dim red light (RL; 4 micromoles photons m-2 s-1) until cell division in the primary leaves was completed, then excised discs were incubated in 10 mM sucrose plus 10 mM KCl in a variety of light treatments.  The growth response of discs exposed to continuous white light (WL) for 16 h was saturated at 100 micromoles m-2 s-1, and did not show reciprocity.  Extensive, but not continuous, illumination was needed for maximal growth.  The wavelength dependence of disc expansion was determined from fluence-response curves obtained from 380 to 730 nm provided by the Okazaki Large Spectrograph.  Blue (BL; 460 nm) and red light (RL; 660 nm) were most effective in promoting leaf cell growth, both in photosynthetically active and inhibited leaf discs.  Far-red light (FR; 730 nm) reduced the effectiveness of RL, but not BL, indicating that phytochrome and a separate blue-light receptor mediate expansion of leaf cells.
Van Volkenburgh
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Botany Department, University of Washington, Seattle 98195, USA.
Cleland
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Watanabe
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D002455:Cell Division / Q000502:physiology / Q000528:radiation effects; D003470:Culture Media; D046508:Culture Techniques; D007887:Fabaceae / Q000166:cytology / Q000254:growth & development* / Q000528:radiation effects; D008027:Light; D017785:Photons; D017440:Photoperiod; D010834:Phytochrome / Q000528:radiation effects; D018515:Plant Leaves / Q000166:cytology* / Q000254:growth & development* / Q000528:radiation effects; D010946:Plants, Medicinal; D011189:Potassium Chloride; D013395:Sucrose
D003470:Culture Media; D010834:Phytochrome; D013395:Sucrose; D011189:Potassium Chloride