Microarray analysis of genes preferentially expressed in differentiating xylem of loblolly pine (Pinus taeda)

Wood formation (xylogenesis) is a critical developmental process for all woody land plants. As an initial step to understand the molecular basis for temporal and spatial regulation of xylogenesis and the effect of the expression of individual genes on physical and chemical properties of wood, we compared transcript profiles of differentiating loblolly pine xylem with needles, megagametophytes, and embryos. A microarray containing approximately 1500 ESTs with Putative functions of interest, selected from loblolly pine normal wood, compression wood, late wood and planings (deeper cell layers) xylem cDNA libraries, was constructed and screened. Using a P-value = 0.01, 440 genes in the xylem versus megagametophyte, 401 genes in the xylem versus embryo and 191 genes in the xylem versus needle tissue comparisons were identified as differentially expressed genes, Among these, 204 genes in the xylem versus megagametophyte, 178 genes in the xylem versus embryo and 85 genes in the xylem versus needle tissue comparisons were identified as genes preferentially expressed in xylem. Real-time RT-PCR was used to test overall validity of the microarray data. (C) 2003 Elsevier Ireland Ltd. All rights reserved.