PROTOPLASTS FROM PHASEOLUS-COCCINEUS L PULVINAR MOTOR CELLS SHOW CIRCADIAN VOLUME OSCILLATIONS

The circadian movement of the lamina of the primary leaf of Phaseolus coccineus is mediated by circadian volume changes of the extensor and flexor cells in the upper and lower half of the laminar pulvinus. Isol ated protoplasts from the extensor, flexor, and flank cells of the pul vinus showed a circadian volume rhythm with a period longer than 24 h. In the case of the flexor protoplasts, we found a period length of 28 h, which is similar to that of the pulvinar cells in situ. In the ext ensor protoplasts, the volume rhythm was synchronized with 14-h light/ 10-h dark cycles. The larger volume was correlated with the early hour s in the light period and the smaller volume with the dark period, as would be expected from the behavior of the extensor cells in situ.