Synthesis of Carotenoid Pigments in Detached Bean Leaves

A method is described for the study of the synthesis of carotenoid pigment in detached green leaves; it is applicable to experiments as long as 24 hours and is sufficiently precise to detect small increases or decreases of pigment on a persample basis. 2. The optimum light intensity for carotene synthesis under these conditions is 600 foot-candles. 3. The temperature coefficient of carotene synthesis at 600 foot-candles over the temperature range of 25°-35° C. is 1.4. 4. The dark synthesis of carotene in the presence of glucose occurs only one-fifteenth as rapidly as the corresponding synthesis in light. 5. There is a slow destruction of carotene in the dark in detached leaves. 6. The estimate of the temperature coefficient of the dark synthesis is 2.9 and of the dark destruction 1.6. 7. Externally supplied glucose and sucrose can contribute to carotene synthesis probably without first being oxidized to carbon dioxide. 8. There is at least one step in the synthesis of carotene which is fluoride-sensitive. 9. It is postulated that carotene synthesis may be represented by the equation shown below, in which P1…n represents an unknown series of intermediates.