Evidence for a light-independent protochlorophyllide reductase in green barley leaves

Evidence is presented that normal light-grown barley plants continue to synthesise chlorophyll when transferred to total darkness. This implies the existence of a light-independent protochlorophyllide reductase in barley as well as the light-dependent enzyme (NADPH protochlorophyllide oxido-reductase) involved in the phototransformation of protochlorophyllide to chlorophyllide. This finding is consistent with an earlier observation by Popov and Dilova (1969) that dark grown barley develops the ability to synthesise chlorophyll in the dark, after several hours exposure to light. Popov and Dilova's findings with etiolated barley are confirmed.