Red Light Induced Change in the Saponin Content of Prolamellar Bodies in A vena sativa

Etioplast, Protochlorophyllide, Prolamellar Body, Saponin, Red Light Exposure to red light of high intensities leads to saponin and prolamellar body degradation in etiolated Avena sativa seedlings. Exposure to red light of low intensities increases the saponin percentage found in prolamellar bodies without changing the overall saponin content. Proto­ chlorophyllide is assumed to act a decisive part in the phototransformation of the PLB as expressed by their saponin content. This is indicated by the action spectrum of this stimulation as well as by experiments with long-wave red (729 nm) and ALA/LA treatment. In weak light the pchlide phototransformation is decelerated-probably due to lack of energy. The PLB are inter­ preted to be modified by the increased pchlide concentration so that more saponin can be incorporated. In further experiments a barley mutant (albina f 17) lacking the capacity to esterify phytol as well as the capacity to degrade the PLB during the greening process was investigated. The results substantiate our hypothesis, as PLB transformation — indicated by PLB saponin concentration — is decelerated with increasing pchlide concentration in greening etioplasts.