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Wall Deposition (wall + deposition)
Selected AbstractsSecondary Cell Wall Deposition in Developing Secondary Xylem of PoplarJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2010Minako Kaneda Although poplar is widely used for genomic and biotechnological manipulations of wood, the cellular basis of wood development in poplar has not been accurately documented at an ultrastructural level. Developing secondary xylem cells from hybrid poplar (Populus deltoides x P. trichocarpa), which were actively making secondary cell walls, were preserved with high pressure freezing/freeze substitution for light and electron microscopy. The distribution of xylans and mannans in the different cell types of developing secondary xylem were detected with immunofluorescence and immuno-gold labeling. While xylans, detected with the monoclonal antibody LM10, had a general distribution across the secondary xylem, mannans were enriched in the S2 secondary cell wall layer of fibers. To observe the cellular structures associated with secondary wall production, cryofixed fibers were examined with transmission electron microscopy during differentiation. There were abundant cortical microtubules and endomembrane activity in cells during the intense phase of secondary cell wall synthesis. Microtubule-associated small membrane compartments were commonly observed, as well as Golgi and secretory vesicles fusing with the plasma membrane. [source] Characterization of ,-tubulin gene distinctively presented in a cytoplasmic male sterile and its maintainer line of non-heading Chinese cabbageJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2009Jingyi Zhang Abstract BACKGROUND: Microtubules are prominent components of the cytoskeleton in every eukaryotic cell. Plant microtubules are essential for a wide variety of cellular functions, including generation of cell polarity, intracellular transport, positioning of organelles, cell wall deposition and cell division. The major component of microtubules is tubulin, an ,,, heterodimer protein with a molecular mass of each subunit of around 50 kDa. Tubulin exists in cells as a mixture of polypeptides differing in their isoelectric points. Some post-translational modifications of tubulins are thought to modulate the functions and localization of microtubules within the cell. RESULTS: The complete sequence of a single-copy ,-tubulin gene Tuba1, belonging to a multiple gene family of non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino), was obtained. The gene was expressed in high levels in young leaves and stamens, and it was also highly expressed during all stages of microsporogenesis in the maintainer. However, there was a distinct difference in ,-tubulin expression between the sterile stage and the normal stages of pollen in a cytoplasmic male sterility line and its maintainer. CONCLUSION:Tuba1 was significantly related to the cell division and elongation of non-heading Chinese cabbage, demonstrating that this gene played an important role in the development of pollen and may be closely related to male sterility. Copyright © 2008 Society of Chemical Industry [source] Microarray analysis of chitin elicitation in Arabidopsis thalianaMOLECULAR PLANT PATHOLOGY, Issue 5 2002Katrina M. Ramonell Summary Chitin oligomers, released from fungal cell walls by endochitinase, induce defence and related cellular responses in many plants. However, little is known about chitin responses in the model plant Arabidopsis. We describe here a large-scale characterization of gene expression patterns in Arabidopsis in response to chitin treatment using an Arabidopsis microarray consisting of 2375 EST clones representing putative defence-related and regulatory genes. Transcript levels for 71 ESTs, representing 61 genes, were altered three-fold or more in chitin-treated seedlings relative to control seedlings. A number of transcripts exhibited altered accumulation as early as 10 min after exposure to chitin, representing some of the earliest changes in gene expression observed in chitin-treated plants. Included among the 61 genes were those that have been reported to be elicited by various pathogen-related stimuli in other plants. Additional genes, including genes of unknown function, were also identified, broadening our understanding of chitin-elicited responses. Among transcripts with enhanced accumulation, one cluster was enriched in genes with both the W-box promoter element and a novel regulatory element. In addition, a number of transcripts had decreased abundance, encoding several proteins involved in cell wall strengthening and wall deposition. The chalcone synthase promoter element was identified in the upstream regions of these genes, suggesting that pathogen signals may suppress the expression of some genes. These data indicate that Arabidopsis should be an excellent model to elucidate the mechanisms of chitin elicitation in plant defence. [source] ANAC012, a member of the plant-specific NAC transcription factor family, negatively regulates xylary fiber development in Arabidopsis thalianaTHE PLANT JOURNAL, Issue 6 2007Jae-Heung Ko Summary Vascular plants evolved to have xylem that provides physical support for their growing body and serves as a conduit for water and nutrient transport. In a previous study, we used comparative-transcriptome analyses to select a group of genes that were upregulated in xylem of Arabidopsis plants undergoing secondary growth. Subsequent analyses identified a plant-specific NAC-domain transcription factor gene (ANAC012) as a candidate for genetic regulation of xylem formation. Promoter-GUS analyses showed that ANAC012 expression was preferentially localized in the (pro)cambium region of inflorescence stem and root. Using yeast transactivation analyses, we confirmed the function of ANAC012 as a transcriptional activator, and identified an activation domain in the C terminus. Ectopic overexpression of ANAC012 in Arabidopsis (35S::ANAC012 plants) dramatically suppressed secondary wall deposition in the xylary fiber and slightly increased cell-wall thickness in the xylem vessels. Cellulose compositions of the cell wall were decreased in the inflorescent stems and roots of 35S::ANAC012 plants, probably resulting from defects in xylary fiber formation. Our data suggest that ANAC012 may act as a negative regulator of secondary wall thickening in xylary fibers. [source] | ||||||||||