Chlorophyll and Carotenoid Destruction in the Absence of Light in Seedlings of Zea Mays L

Abstract

One-week-old seedlings of Zea mays containing known amounts of chlorophyll and carotenoids were placed in the dark and the time course of the destruction of the pigments followed. Both chlorophyll and carotenoids were destroyed rather rapidly at 27[degree]C in the dark. All the chlorophyll disappeared completely after 120 hours in the dark, while the carotenoids fell to 40% of their original value. It was found that, even though the initial pigment concentration varied as much as 150-fold, the time required for the destruction of a given percentage of pigment was independent of the initial concentration. This suggests that the light-independent pigment destruction follows the kinetics of a first-order reaction. Adding sucrose to the environment of the seedlings when placed in the dark effectively protected for a time against depletion of both chlorophyll and carotenoids. Concentrations of 3% sucrose protected the carotenoids completely from destruction in the dark, whereas the chlorophyll concentration decreased 30% in 3% sucrose as compared with 72% destruction in the absence of sucrose. The protective effect of exogenous sucrose on pigment destruction seemed to be to delay the onset of destruction rather than to prevent it from occurring.