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Secondary Wall Formation (secondary + wall_formation)
Selected AbstractsMolecular and Biochemical Evidence for Phenylpropanoid Synthesis and Presence of Wall-linked Phenolics in Cotton FibersJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 7 2009Ling Fan Abstract The mature cotton (Gossypium hirsutum L.) fiber is a single cell with a typically thickened secondary cell wall. The aim of this research was to use molecular, spectroscopic and chemical techniques to investigate the possible occurrence of previously overlooked accumulation of phenolics during secondary cell wall formation in cotton fibers. Relative quantitative reverse transcription-polymerase chain reaction analysis showed that GhCAD6 and GhCAD1 were predominantly expressed among seven gene homologs, only GhCAD6 was up-regulated during secondary wall formation in cotton fibers. Phylogenic analysis revealed that GhCAD6 belonged to Class I and was proposed to have a major role in monolignol biosynthesis, and GhCAD1 belonged to Class III and was proposed to have a compensatory mechanism for monolignol biosynthesis. Amino acid sequence comparison showed that the cofactor binding sites of GhCADs were highly conserved with high similarity and identity to bona fide cinnamyl alcohol dehydrogenases. The substrate binding site of GhCAD1 is different from GhCAD6. This difference was confirmed by the different catalytic activities observed with the enzymes. Cell wall auto-fluorescence, Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC) and chemical analyses confirmed that phenolic compounds were bound to the cell walls of mature cotton fibers. Our findings may suggest a potential for genetic manipulation of cotton fiber properties, which are of central importance to agricultural, cotton processing and textile industries. [source] Interrelation between Lignin Deposition and Polysaccharide Matrices during the Assembly of Plant Cell WallsPLANT BIOLOGY, Issue 1 2002K. Ruel Abstract: The modifications caused by genetic down-regulation of the enzyme cinnamoyl CoA reductase (CCR) from monolignol biosynthetic pathways on tobacco and Arabidopsis thaliana were investigated at the ultrastructural level. A typical result was that the same transformation led to similar abnormality in secondary wall formation of fibres in both plants. The cell wall alterations mainly consisted in an important disorganization and loosening of cellulose microfibrils in the inner part of the S2 layer. This inability of the transformants to form a coherent cell wall coincided with a lack of synthesis of non-condensed forms of lignin in this disorganized region of the wall, as demonstrated by immunolabelling of lignin subunits. A similar disorganization was observed during fibre wall formation in the differentiating tissues of young Populus and A. thaliana plants. The transitory lack of organization of cellulose microfibrils, also coincided with a depletion in non-condensed forms of lignins. These results suggest that such lignin substructures may be involved in the cohesion of secondary walls during cell wall biogenesis. The mutual influence of the cellulose-hemicellulose environment and monolignol local polymerization is discussed. [source] Walls are thin 1 (WAT1), an Arabidopsis homolog of Medicago truncatula NODULIN21, is a tonoplast-localized protein required for secondary wall formation in fibersTHE PLANT JOURNAL, Issue 3 2010Philippe Ranocha Summary By combining Zinnia elegans in vitro tracheary element genomics with reverse genetics in Arabidopsis, we have identified a new upstream component of secondary wall formation in xylary and interfascicular fibers. Walls are thin 1 (WAT1), an Arabidopsis thaliana homolog of Medicago truncatula NODULIN 21 (MtN21), encodes a plant-specific, predicted integral membrane protein, and is a member of the plant drug/metabolite exporter (P-DME) family (transporter classification number: TC 2.A.7.3). Although WAT1 is ubiquitously expressed throughout the plant, its expression is preferentially associated with vascular tissues, including developing xylem vessels and fibers. WAT1:GFP fusion protein analysis demonstrated that WAT1 is localized to the tonoplast. Analysis of wat1 mutants revealed two cell wall-related phenotypes in stems: a defect in cell elongation, resulting in a dwarfed habit and little to no secondary cell walls in fibers. Secondary walls of vessel elements were unaffected by the mutation. The secondary wall phenotype was supported by comparative transcriptomic and metabolomic analyses of wat1 and wild-type stems, as many transcripts and metabolites involved in secondary wall formation were reduced in abundance. Unexpectedly, these experiments also revealed a modification in tryptophan (Trp) and auxin metabolism that might contribute to the wat1 phenotype. Together, our data demonstrate an essential role for the WAT1 tonoplast protein in the control of secondary cell wall formation in fibers. [source] TERE; a novel cis -element responsible for a coordinated expression of genes related to programmed cell death and secondary wall formation during differentiation of tracheary elementsTHE PLANT JOURNAL, Issue 6 2007Hyunjin Pyo Summary The differentiation of water-conducting tracheary elements (TEs) is the result of the orchestrated construction of secondary wall structure, including lignification, and programmed cell death (PCD), including cellular autolysis. To understand the orchestrated regulation of differentiation of TEs, we investigated the regulatory mechanism of gene expression directing TE differentiation. Detailed loss-of-function and gain-of-function analyses of the ZCP4 (Zinniacysteine protease 4) promoter, which confers TE-specific expression, demonstrated that a novel 11-bp cis -element is necessary and sufficient for the immature TE-specific promoter activity. The 11-bp cis -element-like sequences were found in promoters of many Arabidopsis TE differentiation-related genes. A gain-of-function analysis with similar putative cis -elements from secondary wall formation or modification-related genes as well as PCD-related genes indicated that the cis -elements are also sufficient for TE-specific expression of genes. These results demonstrate that a common sequence, designated as the tracheary-element-regulating cis -element, confers TE-specific expression to both genes related to secondary wall formation or modification and PCD. [source] Global transcript profiling of primary stems from Arabidopsis thaliana identifies candidate genes for missing links in lignin biosynthesis and transcriptional regulators of fiber differentiationTHE PLANT JOURNAL, Issue 5 2005Jürgen Ehlting Summary Different stages of vascular and interfascicular fiber differentiation can be identified along the axis of bolting stems in Arabidopsis. To gain insights into the metabolic, developmental, and regulatory events that control this pattern, we applied global transcript profiling employing an Arabidopsis full-genome longmer microarray. More than 5000 genes were differentially expressed, among which more than 3000 changed more than twofold, and were placed into eight expression clusters based on polynomial regression models. Within these, 182 upregulated transcription factors represent candidate regulators of fiber development. A subset of these candidates has been associated with fiber development and/or secondary wall formation and lignification in the literature, making them targets for functional studies and comparative genomic analyses with woody plants. Analysis of differentially expressed phenylpropanoid genes identified a set known to be involved in lignin biosynthesis. These were used to anchor co-expression analyses that allowed us to identify candidate genes encoding proteins involved in monolignol transport and monolignol dehydrogenation and polymerization. Similar analyses revealed candidate genes encoding enzymes that catalyze missing links in the shikimate pathway, namely arogenate dehydrogenase and prephenate aminotransferase. [source] | ||||||||||