THE PLANT CELL, Vol 4, Issue 11 1371-1382, Copyright © 1992 by American Society of Plant Biologists
Downstream DNA Sequences Are Required To Activate a Gene Expressed in the Root Cortex of Embryos and Seedlings
R. A. Dietrich, S. E. Radke and J. J. Harada
Division of Biological Sciences, Section of Botany, University of California, Davis, California 95616
We showed previously that a gene, designated AX92, which is expressed at an
early stage of cortex differentiation in the root apex of oilseed rape
seedlings, is also expressed in embryos. To compare AX92 gene regulation
during embryogenesis and postembryonic growth, we constructed a chimeric
gene consisting of AX92 5[prime] and 3[prime] untranslated and flanking
regions fused with a [beta]-glucuronidase protein coding region. We showed
that the chimeric gene is active in both developing cortex cells in the
root apical meristems of transgenic oilseed rape seedlings and in cortex
cells at the root end of embryonic axes. To determine whether the AX92 gene
is regulated by a common mechanism in embryos and seedlings, we analyzed
the expression of modified chimeric genes. We showed that the AX92 chimeric
gene is regulated combinatorially and that DNA sequences located 3[prime]
of the protein coding region are necessary for its activation in the root
cortex of both embryos and seedlings. Our results suggest that common
regulatory sequences are required to activate the gene in the embryonic and
postembryonic root cortex.
