PLANT PHYSIOLOGY , Vol 110, Issue 4 1069-1079, Copyright © 1996 by American Society of Plant Biologists
|
GENE REGULATION AND MOLECULAR GENETICS |
DNA Sequences That Activate Isocitrate Lyase Gene Expression during Late Embryogenesis and during Postgerminative Growth
J. Z. Zhang, C. M. Santes, M. L. Engel, C. S. Gasser and J. J. Harada
Sections of Plant Biology and Molecular and Cellular Biology, Division of Biological Sciences, University of California, Davis, California 95616
We analyzed DNA sequences that regulate the expression of an isocitrate
lyase gene from Brassica napus L. during late embryogenesis and during
postgerminative growth to determine whether glyoxysomal function is induced
by a common mechanism at different developmental stages.
[beta]-Glucuronidase constructs were used both in transient expression
assays in B. napus and in transgenic Arabidopsis thaliana to identify the
segments of the isocitrate lyase 5[prime] flanking region that influence
promoter activity. DNA sequences that play the principal role in activating
the promoter during post-germinative growth are located more than 1200 bp
upstream of the gene. Distinct DNA sequences that were sufficient for
high-level expression during late embryogenesis but only low-level
expression during postgerminative growth were also identified. Other parts
of the 5[prime] flanking region increased promoter activity both in
developing seed and in seedlings. We conclude that a combination of
elements is involved in regulating the isocitrate lyase gene and that
distinct DNA sequences play primary roles in activating the gene in embryos
and in seedlings. These findings suggest that different signals contribute
to the induction of glyoxysomal function during these two developmental
stages. We also showed that some of the constructs were expressed
differently in transient expression assays and in transgenic plants.
