STIMULATION OF THE SHIBATA SHIFT BY PHOTOCHROME IN THE COTYLEDONS OF THE MUSTARD SEEDLING SINAPIS ALBA L.

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Abstract
Abstract— In the cotyledons of the mustard seedling Sinapis alba L. the duration of the Shibata shift can be greatly shortened by a pretreatment with light pulses prior to the protochlorophyllide– chloro‐phyllide a photoconversion. It was shown that the light pulses act through photochrome (Pfr). Since reversibility of a red light pulse induction by a far‐red light pulse is rapidly lost (within 2 min) it is concluded that at least the initial action of Pfr occurs rapidly in this response. On the other hand, the effect of a red light pulse on the rate of protochlorophyll regeneration in the mustard seedling cotyledons is fully reversible by a far‐red light pulse for more than 5 min. It is concluded that control of protochlorophyll regeneration and control of the Shibata shift by phytochrome cannot be consequences of the same initial action of Pfr Apparently Pfr controls both phenomena independently.