Cis -acting elements for selective expression of two photosynthetic genes in transgenic plants

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Abstract
The most abundant mRNAs in leaves of higher plants encode the small subunit (rbcS) of ribulose 1,5-bisphosphate carboxylase and the chlorophyll a/b-binding (Cab) protein. Nuclear genes for these mRNAs are expressed in an organ-specific manner and their expression is induced by light acting through phytochrome. We have used DNA sequence manipulation in vitro coupled with transgenic plant expression systems to define sequence determinants for regulated expression of these two photosynthetic genes. At least two cis-acting elements for the rbcS genes have been identified. A conserved sequence from the transcription start site to the 5' boundary of the TATA box is involved in light-inducible transcription. In addition, an upstream enhancer-like element (240-280 base pairs) confers phytochrome responsiveness and organ specificity on constitutive promoters. An enhancer-like element (ca. 260 base pairs) in the upstream region of the wheat Cab-1 gene also shows similar functions.