Chloroplast Biogenesis 81: Transient Formation of Divinyl Chlorophyll a Following a 2.5 ms Light Flash Treatment of Etiolated Cucumber Cotyledons

Abstract—The possible conversion of nascent divinyl (DV) chloro‐phyllide a (Chlidea) to DV chlorophylla(Chi a during the early stages of greening in a dark divinyl‐light divinyl‐light/dark divinyl (DDV‐LDV‐LDDV) plant species was investigated. Etiolated cucumber cotyledons (Cucu‐mis sativus L.) were subjected to a 2.5 ms light flash followed by darkness. The DV and monovinyl (MV) components of the protochlorophyllidea(Pchlidea), Chlidea, Pchlideaester and Chiapools were monitored quantitatively by high‐resolution spectrofluorometry, immediately following the light treatments and after various periods in darkness. The light treatment photoconverted DV and MV Pchlideato DV and MV Chlidea. Some photoconversion of MV Pchlide a ester to MV Chi a also appeared to take place. A sharp rise in the level of DV Chi a following the light treatment could not be accounted for by photoconversion of DV Pchlide a ester. It must have arisen by rapid esterification of nascent DV Chlide a. After illumination, the level of DV Chi a rose for 5 s and then declined. The implications of the transient rise and fall of DV Chiacontent following illumination to the Chiabiosynthetic heterogeneity is discussed.