Effect of light on ultrastructure of chloroplasts and post-storage performance of Hydrangea macrophylla (Hydrangeaceae)

Abstract

The plants of Hydrangea are normally stored in dark conditions during shipping. In this study, Hydrangea macrophylla plants were stored for 0-15 d in light or darkness to evaluate the effect of the storage duration and condition on the chloroplast ultrastructure and chlorophyll (Chl) content. Moreover, the plants stored in the dark were transferred to a growth chamber to evaluate their resilience. The plants stored in the dark showed a decrease in number of chloroplasts and starch grains, and granal and intergranal thylakoids with irregular morphology. On the contrary, the same leaves showed an increase of the number of plastoglubuli. The Chl content of the plants remained relatively unchanged during storage under light conditions, but decreased under dark conditions. Transplanted plants stored for 3-9 d in the dark showed normal oval-shape chloroplasts and orderly and dense thylakoids. On the contrary, the plants stored for 12 or 15 d in the dark did not recover normal leaf phenotypes or chloroplast ultrastructure. This study demonstrated that long duration of darkness altered irreversibly the chloroplast ultrastructure and the photosynthetic ability and affected the regrowth potential of Hydrangea macrophylla plants.