Ptxt PL1-27 expression analysis in aspen. (A) Real time RT-PCR analysis of PtxtPL1-27 expression in different tissues and organs of hybrid aspen indicates the highest expression of this gene in developing xylem and organs containing this tissue. Data shown are means of two biological replicates ± standard error. (B) Expression of PtxtPL1-27 in different wood development zones isolated by tangential sectioning. The same amount of total RNA from each zone was blotted onto a membrane and hybridized with a radiolabeled probe corresponding to PtxtPL1-27 cDNA. Phl, phloem; a, vascular cambium; b, expansion zone; c, transition zone; d, secondary wall formation zone; e, cell death zone.