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A Genomic and Molecular View of Wood Formation 总被引:1,自引:0,他引:1
Wood formation is a process derived from plant secondary growth. Different from primary growth, plant secondary growth is derived from cambium meristem cells in the vascular and cork cambia and leads to the girth increase of the plant trunk. In the secondary growth process, plants convert most of photosynthesized products into various biopolymers for use in the formation of woody tissues. This article summarizes the new developments of genomic and genetic characterization of wood formation in herbaceous model plant and tree plant systems. Genomic studies have categorized a collection of the genes for which expression is associated with secondary growth. During wood formation, the expression of many genes is regulated in a stage-specific manner. The function of many genes involved in wood biosyntheses and xylem differentiation has been characterized. Although great progress has been achieved in the molecular and genomic understanding of plant secondary growth in recent years, the profound genetic mechanisms underlying this plant development remain to be investigated. Completion of the first tree genome sequence (Populus genome) provides a valuable genomic resource for characterization of plant secondary growth. 相似文献
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The constituents of plasma membrane proteins, particularly the integral membrane proteins, are closely associated with the differentiation of plant cells. Secondary vascular differentiation, which gives rise to the increase in plant stem diameter, is the key process by which the volume of the plant body grows. However, little is known about the plasma membrane proteins that specifically function in the vascular differentiation process. Proteomic analysis of the membrane proteins in poplar differentiating secondary vascular tissues led to the identification 226 integral proteins in differentiating xylem and phloem tissues. A majority of the integral proteins identified were receptors (55 proteins), transporters (34 proteins), cell wall formation related (27 proteins) or intracellular trafficking (17 proteins) proteins. Gene expression analysis in developing vascular cells further demonstrated that cambium differentiation involves the expression of a group of receptor kinases which mediate an array of signaling pathways during secondary vascular differentiation. This paper provides an outline of the protein composition of the plasma membrane in differentiating secondary vascular tissues and sheds light on the role of receptor kinases during secondary vascular development. 相似文献
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DUF579 (domain of unknown function 579) family proteins contain a DUF579 domain structure but vary greatly in their overall sequence similarity. Several DUF579 proteins have been found to play a role in cell wall biosynthesis in Arabidopsis, while DUF579 family genes have not yet been systematically investigated in Populus. In this study, the Populus DUF579 family proteins were found to be localized in different cell types and subcellular locations. The diverse expression patterns of the proteins indicate that they may perform different functions in Populus. Among the DUF579 family members, PtrDUF579-1 is found to be specifically expressed in vascular cambium zone cells where it is localized in the Golgi apparatus. Suppression of PtrDUF579-1 expression reduced plant height and stem diameter size. Cambium cell division and xylem tissue growth was inhibited while secondary cell wall formation was unchanged in PtrDUF579-1 suppressed plants. Cell walls analysis showed that the composition of the pectin fraction of the cambium cell wall was altered while other polysaccharides were not affected in PtrDUF579-1 suppressed plants. This observation suggest cambium expressed PtrDUF579-1 may affect cell wall biosynthesis and be involved in cambium cell proliferation in Populus. Overall, DUF579 family proteins play a diverse set of roles in Populus. 相似文献
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The Last Step of Syringyl Monolignol Biosynthesis in Angiosperms Is Regulated by a Novel Gene Encoding Sinapyl Alcohol Dehydrogenase 总被引:21,自引:0,他引:21
Laigeng Li Xiao Fei Cheng Jacqueline Leshkevich Toshiaki Umezawa Scott A. Harding Vincent L. Chiang 《The Plant cell》2001,13(7):1567-1586
Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) has been thought to mediate the reduction of both coniferaldehyde and sinapaldehyde into guaiacyl and syringyl monolignols in angiosperms. Here, we report the isolation of a novel aspen gene (PtSAD) encoding sinapyl alcohol dehydrogenase (SAD), which is phylogenetically distinct from aspen CAD (PtCAD). Liquid chromatography-mass spectrometry-based enzyme functional analysis and substrate level-controlled enzyme kinetics consistently demonstrated that PtSAD is sinapaldehyde specific and that PtCAD is coniferaldehyde specific. The enzymatic efficiency of PtSAD for sinapaldehyde was approximately 60 times greater than that of PtCAD. These data suggest that in addition to CAD, discrete SAD function is essential to the biosynthesis of syringyl monolignol in angiosperms. In aspen stem primary tissues, PtCAD was immunolocalized exclusively to xylem elements in which only guaiacyl lignin was deposited, whereas PtSAD was abundant in syringyl lignin-enriched phloem fiber cells. In the developing secondary stem xylem, PtCAD was most conspicuous in guaiacyl lignin-enriched vessels, but PtSAD was nearly absent from these elements and was conspicuous in fiber cells. In the context of additional protein immunolocalization and lignin histochemistry, these results suggest that the distinct CAD and SAD functions are linked spatiotemporally to the differential biosynthesis of guaiacyl and syringyl lignins in different cell types. SAD is required for the biosynthesis of syringyl lignin in angiosperms. 相似文献