Differences in Photosynthesis of Variegated Temple Bamboo Leaves with Various Levels of Variegation are Related to Chlorophyll Biosynthesis and Chloroplast Development

摘要

Variegated temple bamboo (Sinobambusa tootsik f. luteoloalbostriata) is a species of ornamental bamboo (Bambusoideae) that has gained popularity because of its striped or variegated leaves. In this study, a series of experiments was conducted to determine the factors contributing to the leaf color of this species, which included the content of the photosynthetic pigments and the chlorophyll biosynthetic precursors, the photosynthetic parameters, and the microstructure and ultrastructure of the different phenotypes. Discoloration in the leaves of variegated temple bamboo plants is attributed to two possible pathways. One was a block in chlorophyll biosynthesis, which led to the failure in biosynthesis of the thylakoid membrane. The other one was a disruption in chloroplast development. The lack of thylakoid membrane may have inhibited the conversion of coproporphyrinogen III (Coprogen III) to protoporphyrin IX (Proto IX) during the chlorophyll biosynthesis because the enzyme responsible for this conversion, protogen oxidase, is bound to the thylakoid membrane. The abnormalities in chloroplasts and a low concentration of chlorophyll in the variegated leaves led to a significantly lower photosynthetic rate than in the entirely green leaves, as demonstrated in the light-response curve.