Plastid development in distinctively coloured juvenile leaves.
Whatley J. M.
Author Affiliation: Department of Plant Sciences, Oxford University, Oxford OX1 3RB, UK.
New Phytologist 120 : 417-426
Abstract : The juvenile leaves of many tropical and a few temperate plants are translucent and apparently colourless or are white, red or brown in colour rather than green. It is already known that the distinctive colours of the young leaves can result from a delayed increase in chlorophyll content and/or from the masking effects and changing levels of other pigments. The present study deals with the patterns of chloroplast development during leaf growth in coffee, durian, mangoes, Photinia X fraseri cv. Red Robin and cocoa. Even in very young leaves, the mesophyll cells contained chloroplasts, but these were small and few in number. Although conspicuous greening usually occurred only after the leaves were fully expanded, chloroplast development proceeded without interruption throughout leaf growth. The late increase in chlorophyll content was associated with a noticeable increase in the long axes of the chloroplasts and/or their numbers within each cell section. The way in which the overall increase in chloroplast volume per cell was achieved varied between species.