THE ARABIDOPSIS GENE MONOPTEROS ENCODES A TRANSCRIPTION FACTOR MEDIATING EMBRYO AXIS FORMATION AND VASCULAR DEVELOPMENT

The vascular tissues of flowering plants form networks of interconnect ed cells throughout the plant body. The molecular mechanisms directing the routes of vascular strands and ensuring tissue continuity within the vascular system are not known, but are likely to depend on general cues directing plant cell orientation along the apical-basal axis. Mu tations in the Arabidopsis gene MONOPTEROS (MP) interfere with the for mation of vascular strands at all stages and also with the initiation of the body axis in the early embryo. Here we report the isolation of the MP gene by positional cloning. The predicted protein product conta ins functional nuclear localization sequences and a DNA binding domain highly similar to a domain shown to bind to control elements of auxin inducible promoters. During embryogenesis, as well as organ developme nt, MP is initially expressed in broad domains that become gradually c onfined towards the vascular tissues. These observations suggest that the MP gene has an early function in the establishment of vascular and body patterns in embryonic and post-embryonic development.