Photocontrol of the Expression of Genes Encoding Chlorophyll a/b Binding Proteins and Small Subunit of Ribulose-1,5-Bisphosphate Carboxylase in Etiolated Seedlings of Lycopersicon esculentum (L.) and Nicotiana tabacum (L.).

Phytochrome and the blue ultraviolet-A photoreceptor control light-induced expression of genes encoding the chlorophyll a/b binding protein of photosystem II and photosystem I and the genes for the small subunit of the ribulose-1,5-bisphosphate carboxylase in etiolated seedlings of Lycopersicon esculentum (tomato) and Nicotiana tabacum (tobacco). A ;high irradiance response' also controls the induction of these genes. Genes encoding photosystem II- and I-associated chlorophyll a/b binding proteins both exhibit a transient rapid increase in expression in response to light pulse or to continuous irradiation. In contrast, genes encoding the small subunit exhibit a continuous increase in expression in response to light. These distinct expression characteristics are shown to reflect differences at the level of transcription.