THE PLANT CELL, Vol 1, Issue 12 1157-1164, Copyright © 1989 by American Society of Plant Biologists
Cell-Autonomous Behavior of the rolC Gene of Agrobacterium rhizogenes during Leaf Development: A Visual Assay for Transposon Excision in Transgenic Plants
A. Spena, R. B. Aalen and S. C. Schulze
Max-Planck-Institut fur Zuchtungsforschung, Carl-von-Linne-Weg 10, D-5000 Koln 30, Federal Republic of Germany
We describe a genetic switch based on the Ac transposable element of maize
and the rolC gene of Agrobacterium rhizogenes, a dominant gene, which has
pleiotropic effects on plant growth and morphology. Moreover, rolC gene
expression under the control of the 35S cauliflower mosaic virus promoter
decreases chlorophyll content in transgenic tobacco plants. Chlorophyll is
a visible cell-autonomous marker, and it is shown here that the reduction
in chlorophyll content caused by the rolC gene product allows us to
monitor, in palisade or spongy mesophyll cells, Ac excision events
resulting in rolC gene expression as pale-green sectors and spots. Our
results indicate that the rolC gene product behaves in a cell-autonomous
manner during leaf development, at least as far as chlorophyll accumulation
is concerned. In addition, the rolC gene can be useful to evaluate visually
if and when a transposable element is active. Most important, we propose
the use of a transposable element as a tool to activate expression of
morphogenetic genes in a clonal population of cells. This could be
particularly useful when studying genes affecting growth and development
whose constitutive expression can severely impair regeneration of
transgenic plants.
