GENETIC-CONTROL OF FLOWER SHAPE IN ANTIRRHINUM-MAJUS

The asymmetric shape of the Antirrhinum corolla is determined by genes acting differentially along the dorsoventral axis of the flower, Gene s so far identified determine asymmetry by acting in dorsal regions. W e describe a gene, divaricata, which in contrast to previously identif ied genes acts in ventral regions of the flower. We show by the analys is of mutant combinations that the divaricata gene is negatively regul ated by the dorsal genes cycloidea and dichotoma. In addition, we show by the analysis of chromosomal duplications that the divaricata gene acts in a dosage-dependent manner, suggesting that the level of its pr oduct is critical for determining ventral identities.