Influence of Cell Age on Chlorophyll Formation in Light-grown and Etiolated Wheat Seedlings

A method is described for relating the age of a cereal leaf cell to its distance from the leaf base. The rates of chlorophyll synthesis per plastid in the first leaf of light-grown and of greening etiolated seedlings of wheat (Triticum aestivum, var. Maris Dove) increase with cell age. Normally developing plastids of light-grown wheat take over 24 hours to reach the chlorophyll a/b ratio characteristic of mature wheat chloroplasts (4.5), but mature etioplasts need only 8 hours light to achieve this a/b ratio. Plastid greening potential depends only on cell age, whereas the chlorophyll a/b ratio is influenced both by cell age and by light.