THE PLANT CELL, Vol 4, Issue 8 971-981, Copyright © 1992 by American Society of Plant Biologists
A Rice cab Gene Promoter Contains Separate cis-Acting Elements That Regulate Expression in Dicot and Monocot Plants
S. Luan and L. Bogorad
Department of Cellular and Developmental Biology, Harvard University, 16 Divinity Avenue, Cambridge, Massachusetts 02138
The major light-harvesting chlorophyll a/b binding proteins of the
photosynthetic apparatus are encoded by families of nuclear cab genes. The
expression of most cab genes is tissue specific and photoregulated in
angiosperms. In transgenic tobacco plants, expression of the reporter gene
[beta]-glucuronidase (GUS) is photoregulated and tissue specific from
5[prime] upstream sequences of the rice cab1R gene; deletion of sequences
upstream from position -170 with respect to the transcription start site
eliminates the enhanced and photoregulated expression in the transgenic
plants. Using an in situ transient expression assay, we have determined
that the sequence OCT-R, an octamer repeat that lies within the -269 to
-170 region of cab1R, is essential for photoregulated expression of the
chimeric GUS gene in leaf cells of maize and rice but is not required for
expression in illuminated tobacco leaves. Conversely, box III*- and
G-box-like sequences found near OCT-R in cab1R are necessary for high-level
transient expression of the reporter gene in tobacco leaf tissue but are
not required for transient expression in maize or rice leaves.
