Figure 4

Cell wall genes and ancestral xylem genes are relatively more conserved in diverse plants. Putative cell wall, non-cell-wall, vascular plant-specific xylem (VSX) and ancestral xylem genes within xylem unigenes of radiata pine, loblolly pine, white spruce and poplar were blasted with gene indices (tblastx) of pine and spruce, and gene models (blastx) of poplar, Arabidopsis, rice, Selaginella and moss. Percentage of hits is presented on the Y-axis at three E-value cut-offs (0, 1e-50 and 1e-5). Different numbers of hits observed with cell wall and non-cell-wall genes, as well as with VSX and ancestral xylem genes were statistically tested assuming a binomial distribution. All comparisons showed statistical significances (P < 0.001) (data not show for the simplicity of the figure) except for a few between conifers at 1e-5.