MOLECULAR AND ANATOMICAL ANALYSIS OF CELL EXPANSION AND DIFFERENTIATION IN PLANTS

¹ Department of Biochemistry, University of Queensland, Brisbane, Queensland 4072, Australia

² School of Land and Food, University of Queensland, Brisbane, Queensland 4072, Australia

³ Centre for Microscopy and Microanalysis, University of Queensland, Brisbane, Queensland 4072, Australia

⁴ Mendel Biotechnology Inc., 21375 Cabot Boulevard, Hayward, CA 94545 USA

A two component Ds/sAc transposon system in transgenic tomato (1) has been used to tag and clone important plant development genes (2, 3). The involvement of the Dem (Defective embryo and meristems) gene in cell expansion during plant morphogenesis will be the focus of this report. Dem is required for the correct organization of developing embryos, and the shoot and root apical tissues where differentiation occurs (3). Stable insertion of Ds in Dem resulted in abnormal seedlings and termination of growth shortly after germination (3). To assess the mutant phenotype in the later stages of plant development, a genotype was developed for the somatic tagging of Dem (MR and BC, unpub. data). The phenotype of chimeric plants demonstrated that the Dem gene is required for cell expansion in the upper (adaxial) portion of the leaf, i.e. the palisade and upper epidermal cells. Collectively, the stable and variegated mutant phenotypes imply that Dem plays a key role in cell expansion during differentiation in plants. 1. Carroll, B. J. et al. (1995) Genetics 139, 407-420. 2. Keddie, J. S. et al. (1996) EMBO J 15, 4208-4217. 3. Keddie, J. S. et al. (1998) Plant Cell 10, 877-888.