Removal of magnesium by Mg-dechelatase is a major step in the chlorophyll-degrading pathway in Ginkgo biloba in the process of autumnal tints

摘要

Autumnal tints are one of the most manifest and fascinating natural phenomena, but the mechanism of chlorophyll (Chl)-breakdown in deciduous trees has not been fully elucidated. In this study, we analyzed the composition of Chi-related compounds and determined the activities of initial Chi-degrading enzymes in Ginkgo leaves at various stages in the process of autumnal coloring. Only pheophytin a (Pheo a, Mg-free Chi a) was detected in yellow leaves by HPLC analysis, and the activity of Mg-dechelatase in yellow leaves was found to be higher than in green leaves. These findings showed that the removal of magnesium from Chi a occurred in advance of dephytylation in the Ginkgo. [References: 9]