Photosynthesis-associated gene families: Differences in response to tissue-specific and environmental factors

The endogenous small subunit of the ribulose-1,5-bisphosphate carboxylase gene rbcS and the light-harvesting chlorophyll a/b-binding protein gene(LHCP)of pea are expressed in a light-inducible manner and are active mainly in green chloroplast-containing tissue. Chimeric genes under control of the 5′-flanking sequences of the rbcS ss3.6 or LHCP AB80 genes from pea were used to study the factors relating to the tissue-specific and light-inducible expression of these nuclear-encoded genes in transgenic tobacco plants. The results show that plastid development plays a crucial role in the activation of expression of these chimeric genes. Particular members of each of the above gene families respond differently to tissue-specific and environmental factors. Furthermore, the light-inducible expression directed by the 5′-flanking sequence of ss3.6 rbcS gene is not exclusively mediated by phytochrome, but probably is controlled in large part by another photoreceptor.