Abstract
In higher plants, cell-cell communication is thought to be essential for vascular system formation. Xylogen, an arabinogalactan protein (AGP), has been isolated from Zinnia cell culture as a tracheary element differentiation inducing factor that directs continuous formation of xylem strands. In Arabidopsis genome, there are at least 15 genes (AtXYP1 ~ AtXYP15) homologous to the Zinnia xylogen gene. These genes encode proteins having the signal peptide, the well-conserved nsLTP domain, and in some cases, AGP-like sequence. Analysis of expression patterns of AtXYP1~AtXYP15 promoter::GUS transgenic plants suggest that AtXYP2 plays a main role as xylogen in Arabidopsis plants. Observation of transgenic plants with AtXYP2-GFP fusion protein indicates that AtXYP2 localizes on plasma membrane. Currently we are producing transgenic plants with site-directed mutagenized AtXYP2 genes and analyzing the effect of deletion of nsLTP and AGP domains on vascular development.
