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Transcriptomic changes during cell wall biogenesis and modifications during xylogenesis in stems and pioneer roots of Populus trichocarpa

ABSTRACT: We studied the changes that occur in gene transcription and the biosynthesis of cell-wall-related compounds during xylogenesis in Populus trichocarpa pioneer roots and stems. Transcriptional profiling was conducted with the use of microarrays to identify genes involved in xylem formation. Pioneer roots were examined in segments corresponding to their developmental stage: apical meristem (PR1), primary development (PR2), and secondary development (PR3). Comparative segments were used to analyze xylogenesis in stems: apical meristem with primary development (PS1), secondary development (PS2), and isolated secondary xylem (PS3). Results indicated that only approximately 10% of the genes that were identified to be differentially expressed during xylogenesis were common to both pioneer roots and stems. Despite the dissimilarity in gene expression, however, many fundamental mechanisms were similar, e.g. the pattern of expression of genes involved in the biosynthesis of cell wall proteins, polysaccharides and lignins. While hemicellulose degradation was typical for stems, possibly due to the intensive level of cell wall lignification. Our study is the first to conduct a comprehensive analysis, at the structural and molecular level, of xylogenesis, and clearly reveals the great complexity of molecular mechanisms underlying cell wall formation and modification during xylogenesis.

ORGANISM(S): Populus trichocarpa Populus sp.

PROVIDER: GSE126842 | GEO | 2019/10/14

REPOSITORIES: GEO

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Project description:rs04-03_myb - myb - Xylogenesis is a fundamental developmental process that is specific of vascular plants. It allows the formation of xylem, also called wood in trees, a complex tridimensional tissue composed of different cell types. This process occurs through the control of fundamental cell mechanisms like cell division and differentiation, secondary cell wall synthesis, lignin deposition and programmed cell death. Xylogenesis is controlled spatially and temporally by specific genetic programs that involve hundreds of genes. For instance, lignin biosynthetic genes, CAD and CCR, are specifically expressed during xylogenesis through MYB transcription factor binding sites, a process that seems to be common to all vascular plants. We have cloned two xylem specific MYB transcription factors, EgMYB1 et EgMYB2, in Eucalyptus. Interestingly, they are able to bind MYB consensus sequences of CAD and CCR promoters in vitro and to modulate CAD and CCR expression in vivo. When overexpressed in Arabidopsis or tobacco, they affect xylem structure by changing cell wall structure and quality. To follow expression changes of Arabidopsis genes in transgenic plants overexpressing Eg MYB1 and EgMYB2 should help us to find out which genes might be target of those transcription factors. This should help us to decipher the actual role of those two MYBs in xylogenesis, two new members of a large family of transcription factors in plants. - Xylogenesis is a fundamental developmental process that is specific of vascular plants. It allows the formation of xylem, also called wood in trees, a complex tridimensional tissue composed of different cell types. This process occurs through the control of fundamental cell mechanisms like cell division and differentiation, secondary cell wall synthesis, lignin deposition and programmed cell death. Xylogenesis is controlled spatially and temporally by specific genetic programs that involve hundreds of genes. For instance, lignin biosynthetic genes, CAD and CCR, are specifically expressed during xylogenesis through MYB transcription factor binding sites, a process that seems to be common to all vascular plants. We have cloned two xylem specific MYB transcription factors, EgMYB1 et EgMYB2, in Eucalyptus. Interestingly, they are able to bind MYB consensus sequences of CAD and CCR promoters in vitro and to modulate CAD and CCR expression in vivo. When overexpressed in Arabidopsis or tobacco, they affect xylem structure by changing cell wall structure and quality. To follow expression changes of Arabidopsis genes in transgenic plants overexpressing Eg MYB1 and EgMYB2 should help us to find out which genes might be target of those transcription factors. This should help us to decipher the actual role of those two MYBs in xylogenesis, two new members of a large family of transcription factors in plants. Keywords: gene knock in (transgenic)

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Transcriptomic changes during cell wall biogenesis and modifications during xylogenesis in stems and pioneer roots of Populus trichocarpa

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