The Correlated Appearance of Prolamellar Bodies, Protochlorophyll(ide) Species, and the Shibata Shift during Development of Bean Etioplasts in the Dark

The structure and physiology of the etioplast was investigated in developing primary leaves of 3- to 9-day-old dark-grown bean (Phaseolus vulgaris L. var. Red Kidney) seedlings. Increase in total protochlorophyll(ide) content followed that of leaf fresh weight. In 3- to 4-day-old bean leaves more than 50% of the protochlorophyll(ide) is in the form of protochlorophyll(ide) 628, which is nontransformable by light. Most of the transformable pigment is protochlorophyll(ide) 635, with smaller amounts of protochlorophyll(ide) 650. During leaf development from the 3rd to the 7th day phototransformable protochlorophyll(ide) with an absorbance maximum at 650 nm accumulates faster than nontransformable protochlorophyll(ide) or protochlorophyll(ide) 635. This increase in protochlorophyll(ide) 650 is correlated with the formation and enlargement of prolamellar bodies.The transformable protochlorophyll(ide) is converted by light directly to chlorophyll(ide) 672 in young leaves which do not yet have prolamellar bodies, and chlorophyll(ide) 672 may arise largely from the protochlorophyll(ide) 635. In older leaves the protochlorophyll(ide), largely protochlorophyll(ide) 650, is converted to chlorophyll(ide) 683, and a Shibata shift results in a change in the wavelength of absorption to 672 nm. The increase in protochlorophyll(ide) 650, the formation of prolamellar bodies, and the presence of the Shibata shift appear to be closely correlated. A model is briefly presented to provide a unified interpretation of these findings, including certain similarities between dark-grown Euglena cells and 3- to 4-day-old etiolated bean leaves.