Project description:The within-tree variation in wood properties constitutes an exceptional model to study the mechanisms that adjust the different biosynthetic pathways providing substrates with the massive and variable demands of different biosynthetic reactions of cell wall polymers. Although a few genes have been reported as differentially expressed in differentiating compression wood compared to normal or opposite wood, the expression of a larger set of genes is expected to change due the broad range of features that distinguish this reaction wood. By combining the construction of different cDNA libraries with microarray analyses, using samples from different Pinus pinaster provenances collected in different years and geographic locations, we have identified a total of 496 genes that change their expression during differentiation of compression wood (331 up-regulated and 165 down-regulated compared to opposite wood). Consistent with the well-known structural and chemical characteristics of compression wood, a large number of genes involved in the biosynthesis of cell wall components were shown to be up-regulated during compression wood differentiation, including genes involved in synthesis of cellulose, hemicellulose, lignin and lignans. In particular, further analysis of a set of these genes involved in providing S-adenosylmethionine, ammonium recycling, lignin and lignans biosynthesis showed parallel expression profiles to levels of lignin accumulation in cells undergoing xylogenesis in vivo and in vitro. The comparative transcriptomic analysis of compression and opposite wood formation in this work have revealed a broad spectrum of coordinated transcriptional modulation of biosynthetic reactions for different cell wall polymers associated to within-tree variations in softwood structure and composition. In particular, it suggest the occurrence of a mechanism that modulates at transcriptional level genes encoding enzymes involved in S-adenosylmethionine synthesis and ammonium assimilation with coniferyl alcohol demand for lignin and lignan synthesis, as a key metabolic requirement in cells undergoing lignification.

Project description:The within-tree variation in wood properties constitutes an exceptional model to study the mechanisms that adjust the different biosynthetic pathways providing substrates with the massive and variable demands of different biosynthetic reactions of cell wall polymers. Although a few genes have been reported as differentially expressed in differentiating compression wood compared to normal or opposite wood, the expression of a larger set of genes is expected to change due the broad range of features that distinguish this reaction wood. By combining the construction of different cDNA libraries with microarray analyses, using samples from different Pinus pinaster provenances collected in different years and geographic locations, we have identified a total of 496 genes that change their expression during differentiation of compression wood (331 up-regulated and 165 down-regulated compared to opposite wood). Consistent with the well-known structural and chemical characteristics of compression wood, a large number of genes involved in the biosynthesis of cell wall components were shown to be up-regulated during compression wood differentiation, including genes involved in synthesis of cellulose, hemicellulose, lignin and lignans. In particular, further analysis of a set of these genes involved in providing S-adenosylmethionine, ammonium recycling, lignin and lignans biosynthesis showed parallel expression profiles to levels of lignin accumulation in cells undergoing xylogenesis in vivo and in vitro. The comparative transcriptomic analysis of compression and opposite wood formation in this work have revealed a broad spectrum of coordinated transcriptional modulation of biosynthetic reactions for different cell wall polymers associated to within-tree variations in softwood structure and composition. In particular, it suggest the occurrence of a mechanism that modulates at transcriptional level genes encoding enzymes involved in S-adenosylmethionine synthesis and ammonium assimilation with coniferyl alcohol demand for lignin and lignan synthesis, as a key metabolic requirement in cells undergoing lignification. Two-condition experiment including dye-swap experiments, Compression Differentiating Xylem vs. Opposite Differentiating Xylem. Biological replicates: 4 compression xylem, 4 opposite xylew, harvested from four different individual pine trees. Two replicates per array.

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Compression Xylem vs. Opposite Xylem

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