ISOLATION AND CHARACTERIZATION OF THE TOMATO HOMEOBOX GENE THOM1

We have screened a cDNA library prepared from tomato (Lycopersicon esc ulentum Mill, cv, VFNT Cherry) shoot tips for homeobox-containing clon es. The isolated cDNA clone THOM1 (tomato homeobox gene 1) contains a homeobox, a leucine zipper motif and and an acidic region. These featu res support the hypothesis that the THOM1 gene product acts as a trans criptional activator. THOM1 is highly expressed in the vegetative shoo t apical meristem, the floral meristem and axillary meristems. Young d erivatives of these meristems show similar levels of THOM1 transcripts which decrease with increasing age of the respective tissue. The THOM 1 gene is located in the centromere region of chromosome 1 and belongs to a small gene family of the tomato genome.