THE PLANT CELL, Vol 1, Issue 2 209-215, Copyright © 1989 by American Society of Plant Biologists
Sequences 5[prime] to Translation Start Regulate Expression of Petunia rbcS Genes
C. Dean, M. Favreau, J. Bedbrook and P. Dunsmuir
Advanced Genetic Sciences, 6701 San Pablo Avenue, Oakland, California 94608
The promoter sequences that contribute to quantitative differences in
expression of the petunia genes (rbcS) encoding the small subunit of
ribulose bisphosphate carboxylase have been characterized. The promoter
regions of the two most abundantly expressed petunia rbcS genes, SSU301 and
SSU611, show sequence similarity not present in other rbcS genes. We
investigated the significance of these and other sequences by adding
specific regions from the SSU301 promoter (the most strongly expressed
gene) to equivalent regions in the SSU911 promoter (the least strongly
expressed gene) and assaying the expression of the fusions in transgenic
tobacco plants. In this way, we characterized an SSU301 promoter region
(either from -285 to -178 or -291 to -204) which, when added to SSU911, in
either orientation, increased SSU911 expression 25-fold. This increase was
equivalent to that caused by addition of the entire SSU301
5[prime]-flanking region. Replacement of SSU911 promoter sequences between
-198 and the start codon with sequences from the equivalent region of
SSU301 did not increase SSU911 expression significantly. The -291 to -204
SSU301 promoter fragment contributes significantly to quantitative
differences in expression between the petunia rbcS genes.
