THE PLANT CELL, Vol 8, Issue 3 349-362, Copyright © 1996 by American Society of Plant Biologists
Ectopic Expression of the Maize Homeobox Genes ZmHox1a or ZmHox1b Causes Pleiotropic Alterations in the Vegetative and Floral Development of Transgenic Tobacco
B. Uberlacker, B. Klinge and W. Werr
Institut fur Entwicklungsbiologie der Universitat zu Koln, Gyrhofstrasse 17, 50923 Cologne, Germany
The ZmHox1a and ZmHox1b (for Zea mays homeobox) genes map on chromosomes 8
and 6, respectively. Both homeobox genes encode proteins that show 91%
similarity and are transcribed simultaneously in meristematic and
proliferating cells of the maize plant. To gain insight into the biological
function of these genes, both open reading frames were expressed in
tobacco, under the control of the cauliflower mosaic virus 35S promoter.
The resulting transgenic ZmHox1a or ZmHox1b plants showed identical
phenotypic alterations that fall into three classes: size reduction,
formation of adventitious shoots, and homeotic floral transformations.
Approximately 30% of the ZmHox1-expressing plants grew to only one-third of
the wild-type size, and most axillary buds gave rise to lateral shoots.
Flower abnormalities included formation of petaloid stamens and development
of secondary flowers within the primary gynoecium. Therefore, the ectopic
expression of the maize ZmHox1 homeobox gene products affects the
vegetative as well as the reproductive phase of tobacco plants. All
phenotypic alterations were transmitted to the next generation.
