Browsing by Subject "Zinnia"
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Item Molecular cloning and characterization of cellulose synthase genes expressed during tracheary elements differentiation in cultures of Zinnia elegans(Texas Tech University, 2002-08) Hwang, SangjoonIsolated mesophyll cells of Zinnia elegans induced to differentiate into tracheary elements (TEs) semi-synchronously in culture are a valuable experimental system for research on cellulose synthesis. To explore a possible cellulose synthase gene family that might be specific to secondary wall thickening, a RACE (Rapid Amplification of cDNA Ends) strategy was applied using total RNA from Zinnia cells cultured in differentiation medium for 60 hours. Three cDNA fragments, designated ZeCesAl (AF323039), ZeCesA2 (AF323040), and ZeCesA3 (AF323041), that were mainly expressed during TE differentiation and not during primary wall synthesis were isolated from 3' RACE technique. A cDNA fragment corresponding to the 5' part of ZeCesAl gene was obtained from the 5' RACE technique. A full-length ZeCesAl cDNA sequence was constructed by overlapping the 5' and 3'-RACE fragments. In common with known plant cellulose synthase genes iCesAs), ZeCesAl encodes a predicted membrane protein having conserved motifs and domain structure. Based on amino acid sequence comparisons and phylogenetic analyses, ZeCesAl-3 show a closer relationship to secondary wall-specific CesAs, especially to GhCesAl, AtCesAS, and PtCesA2, than to primary wallspecific CesAs. This indicates that ZeCesAl 3 are orthologs of CesA genes from other species that belong to the secondary wall clade. ZeCesAl-3 represent very similar sequences and define a set of paralogous genes, probably duplicated from the same original gene. Northern blot analyses and tissue printing revealed that ZeCesAl-3 were expressed in a close association with TE differentiation in vitro, and ZeCesAl was expressed in regions with developing vascular bundles in stems and leaves.Item The investigation of secondary cell wall deposition in differentiating Zinnia cell suspension cultures(Texas Tech University, 1993-12) Taylor, James G.The study of plant cell walls has been of great interest for many years because of the importance of the cell wall in plant development and in materials of economic utility such as fiber and wood A plant cell wall is defined as the "layer of structural material found external to the protoplast" (Fry, 1988 p 2) in plant cells. The protective and strengthening characteristics of cell walls influence or possibly regulate the cell's shape, which in the end determines the form and adaptability of a plant (Roberts, 1989). Understanding cell walls and their components can lead to better utilization of plants and provide a possible basis for developing modified plants with increased commercial utility (Shedletzky et al., 1990). The plant cell wall is now realized to have many critical functions in plant development and survival. These include: (a) regulating plant morphogenesis through controlled orientation of cellulose microfibrils; (b) mediating plant responses to pathogenic and environmental stress; (c) housing a diversity of complex polysaccharides, fragments of which can act as developmental signals; (d) providing an environment for the function of numerous enzymes; and (e) interacting with cytoplasmic components through linker proteins in the plasma membrane to regulate development (Roberts, 1989, 1990). Despite this increase in ascribed importance, our true understanding of wall composition and deposition is in its infancy, particularly for secondary cell walls.Item The isolation and characterization of partial cDNAs associated with In Vitro tracheary element formation(Texas Tech University, 1995-08) Koonce, Linda TDifferential Display provides a sensitive method for quickly isolating and cloning cDNAs with corresponding mRNA transcripts that are differentially expressed between two different tissues or cell t5rpes. This technique provided a means by which three cDNAs with corresponding transcripts that are strongly expressed in suspension cultures of Zinnia mesophyll cells differentiating into tracheary elements were isolated. One transcript (63.30) has similarity to the non-histone protein 2 high mobility group-like protein in yeast, and to ribosomal proteins from yeast and the PRL2 protein from A. thaliana. The 63.30 transcript was found to be expressed in newly forming tracheary elements and phloem fibers and is expressed in response to auxin and/or cytokinin. A second transcript (54.6) was also determined to be expressed in newly forming tracheary elements and phloem fibers and is expressed in response to auxin and/or cytokinin. The deduced protein sequence of the 54.6 transcript shares some similarity to membrane spanning domains and the voltage sensor domain of the alpha subunit of the dihydropyridine- sensitive voltage-dependent calcium channel isolated from rat aorta. A third cDNA was isolated and expression of the transcript was found in in vitro differentiating tracheary elements, but no expression was detected in any whole plant tissue. It is possible that this transcript is a very rare species or is a result of the stress of culturing. No similarities to this transcript were detected by searches of the Blast/NCBI databases.