The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Steven P Briggs - One of the best experts on this subject based on the ideXlab platform.
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modification of a specific class of plasmodesmata and loss of sucrose export ability in the sucrose export defective1 maize mutant
The Plant Cell, 1996Co-Authors: William A Russin, Ray F. Evert, Peter J Vanderveer, Thomas D Sharkey, Steven P BriggsAbstract:We report on the export capability and structural and ultrastructural characteristics of leaves of the sucrose export defective1 (sed1; formerly called sut1) maize mutant. Whole-leaf autoradiography was combined with light and transmission electron microscopy to correlate leaf structure with differences in export capacity in both wild-type and sed1 plants. Tips of sed1 blades had abnormal accumulations of starch and anthocyanin and distorted vascular tissues in the minor veins, and they did not export sucrose. Bases of sed1 blades were structurally identical to those of the wild type and did export sucrose. Electron microscopy revealed that only the plasmodesmata at the bundle sheath-vascular Parenchyma Cell interface in sed1 minor veins were structurally modified. Aberrant plasmodesmal structure at this critical interface results in a symplastic interruption and a lack of phloem-loading capability. These results clarify the pathway followed by photosynthates, the pivotal role of the plasmodesmata at the bundle sheath-vascular Parenchyma Cell interface, and the role of the vascular Parenchyma Cells in phloem loading.
Laurence D Melton - One of the best experts on this subject based on the ideXlab platform.
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Comparison of celery (Apium graveolens L.) collenchyma and Parenchyma Cell wall polysaccharides enabled by solid-state (13)C NMR.
Carbohydrate Research, 2016Co-Authors: Zoran D. Zujovic, Da Chen, Laurence D MeltonAbstract:Collenchyma Cells with their thickened walls are one of specific mechanical support tissues for plants, while Parenchyma Cells are thin walled and serve multiple functions. The Parenchyma tissue is what you enjoy eating, while collenchyma, because of its fibrous nature, is not so attractive. Celery is a useful model for comparing the Cell walls (CWs) of the two Cell types such as collenchyma and Parenchyma. However, to date, the structural characteristics of collenchyma and Parenchyma Cell walls from the same plant have not been compared. Monosaccharide composition suggested the collenchyma Cell walls contained less pectin but more hemiCellulose in comparison to Parenchyma. High-resolution solid-state NMR spectra of highly mobile pectins revealed that the arabinan signals were more evident in the collenchyma spectrum, while galactan showed a much stronger resonance in the Parenchyma spectrum. In addition, methyl esterified and non-esterified galacturonic acid signals were observed in Parenchyma CWs, but only the latter one appeared in the collenchyma. The ratio of Cellulose surface/interior obtained from CP/MAS spectra for collenchyma suggested the Cellulose microfibrils were ~2.4 nm, while in the Parenchyma, these were somewhat larger. X-ray diffraction indicated the size of the Cellulose microfibrils were the same for both types of CWs.
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celery apium graveolens Parenchyma Cell walls Cell walls with minimal xyloglucan
Physiologia Plantarum, 2002Co-Authors: Julian Thimm, David J Burritt, William A Ducker, Roger H Newman, Ian M Sims, Laurence D MeltonAbstract:The primary walls of celery (Apium graveolens L.) Parenchyma Cells were isolated and their polysaccharide components characterized by glycosyl linkage analysis, cross-polarization magic-angle spinning solid-state 13C nuclear magnetic resonance (CP/MAS 13C NMR) and X-ray diffraction. Glycosyl linkage analysis showed that the Cell walls consisted of mainly Cellulose (43 mol%) and pectic polysaccharides (51 mol%), comprising rhamnogalacturonan (28 mol%), arabinan (12 mol%) and galactan (11 mol%). The amounts of xyloglucan (2 mol%) and xylan (2 mol%) detected in the Cell walls were strikingly low. The small amount of xyloglucan present means that it cannot coat the Cellulose microfibrils. Solid-state 13C NMR signals were consistent with the constituents identified by glycosyl linkage analysis and allowed the walls to be divided into three domains, based on the rigidity of the polymers. Cellulose (rigid) and rhamnogalacturonan (semi-mobile) polymers responded to the CP/MAS 13C NMR pulse sequence and were distinguished by differences in proton spin relaxation time constants. The arabinans, the most mobile polymers, responded to single-pulse excitation (SPE), but not CP/MAS 13C NMR. From solid-state 13C NMR of the Cell walls the diameter of the crystalline Cellulose microfibrils was determined to be approximately 3 nm while X-ray diffraction of the Cell walls gave a value for the diameter of approximately 2 nm.
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Cell wall compositions of raw and cooked corms of taro colocasia esculenta
Journal of the Science of Food and Agriculture, 2001Co-Authors: My Le Quach, Laurence D Melton, Philip J Harris, Jeremy N Burdon, Bronwen G SmithAbstract:The monosaccharide compositions of Parenchyma Cell walls of raw and cooked corms of taro, Colocasia esculenta cv Tausala Pink, were determined. The Cell wall constituents were sequentially extracted using CDTA, Na2CO3, 1 M KOH, 4 M KOH and water to leave a final residue (α-Cellulose). The monosaccharide compositions of the Cell walls and Cell wall fractions from the raw and cooked corms were consistent with the presence in these Cell walls of large amounts of Cellulose and pectic polysaccharides. The monosaccharide composition of the Cell walls of the raw corms resembled the monosaccharide compositions of primary Cell walls of other non-commelinoid monocotyledons and dicotyledons. Cooking of the corms resulted in alteration of the Cell walls, with solubilisation of pectic polysaccharides occurring earlier in the sequential fractionation and possibly changes in the extractability of xyloglucans and/or xylans. © 2000 Society of Chemical Industry
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celery apium graveolens l Parenchyma Cell walls examined by atomic force microscopy effect of dehydration on Cellulose microfibrils
Planta, 2000Co-Authors: Julian Thimm, David J Burritt, William A Ducker, Laurence D MeltonAbstract:Atomic force microscopy (AFM) was used to image celery (Apium graveolens L.) Parenchyma Cell walls in situ. Cellulose microfibrils could clearly be distinguished in topographic images of the Cell wall. The microfibrils of the hydrated walls appeared smaller, more uniformly distributed, and less enmeshed than those of dried peels. In material that was kept hydrated at all times and imaged under water, the microfibril diameter was mainly in the range 6–25 nm. The Cellulose microfibril diameters were highly dependent on the water content of the specimen. As the water content was decreased, by mixing ethanol with the bathing solution, the microfibril diameters increased. Upon complete dehydration of the specimen we observed a significant increase in microfibril diameter. The procedure used to dehydrate the Parenchyma Cells also influenced the size of Cellulose microfibrils with freeze-dried material having larger diameters than air-dried material.
Maciej A Zwieniecki - One of the best experts on this subject based on the ideXlab platform.
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the functional role of xylem Parenchyma Cells and aquaporins during recovery from severe water stress
Plant Cell and Environment, 2017Co-Authors: Francesca Secchi, Chiara Pagliarani, Maciej A ZwienieckiAbstract:Xylem Parenchyma Cells [vessel associated Cells (VACs)] constitute a significant fraction of the xylem in woody plants. These Cells are often closely connected with xylem vessels or tracheids via simple pores (remnants of plasmodesmata fields). The close contact and biological activity of VACs during times of severe water stress and recovery from stress suggest that they are involved in the maintenance of xylem transport capacity and responsible for the restoration of vessel/tracheid functionality following embolism events. As recovery from embolism requires the transport of water across xylem Parenchyma Cell membranes, an understanding of stem-specific aquaporin expression patterns, localization and activity is a crucial part of any biological model dealing with embolism recovery processes in woody plants. In this review, we provide a short overview of xylem Parenchyma Cell biology with a special focus on aquaporins. In particular we address their distributions and activity during the development of drought stress, during the formation of embolism and the subsequent recovery from stress that may result in refilling. Complemented by the current biological model of Parenchyma Cell function during recovery from stress, this overview highlights recent breakthroughs on the unique ability of long-lived perennial plants to undergo cycles of embolism-recovery related to drought/rewetting or freeze/thaw events.
Marina Vuković - One of the best experts on this subject based on the ideXlab platform.
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Parenchyma Cell wall structure in twining stem of Dioscorea balcanica
Cellulose, 2017Co-Authors: Jasna Simonović Radosavljević, Jelena Bogdanović Pristov, Aleksandra Lj. Mitrović, Gabor Steinbach, Gregory Mouille, Srđan Tufegdžić, Vuk Maksimović, Dragosav Mutavdžić, Dušica Janošević, Marina VukovićAbstract:Anatomical adaptation of liana plants includes structural changes in Cell walls of different tissues: fibers, vessel elements and tracheids. However, the contribution of Parenchyma Cells to stem twining in liana plants is mostly unknown. The aim of this investigation is to determine changes in stem Parenchyma Cell walls that are correlated with the twinning process in liana plants. Parenchyma Cell wall structure was studied on the stem cross sections of straight and twisted internodes of monocotyledonous liana Dioscorea balcanica , by different microscopy techniques: light microscopy, scanning electron microscopy, fluorescence detected linear dichroism microscopy and Fourier transform infrared microspectrometry. In addition, chemical analysis of the entire stem internodes was performed using photometric and chromatographic methods. Parenchyma Cell walls of twisted D. balcanica internodes are characterized by: lower amounts of Cellulose (obtained by FTIR microspectrometry) with different Cellulose microfibril orientation (shown by Scanning electron microscopy), but no changes in “Cellulose fibril order” (obtained by Differential polarization laser scanning microscopy); lower amounts of xyloglucan, higher amounts of xylan, higher amounts of lignin with modified organization—less condensed lignin (obtained by FTIR microspectrometry). At the same time, chemical analysis of the entire internodes did not show significant differences in lignin content and Cell wall bound phenols related to stem twining, except for the presence of diferulate cross-links exclusively in twisted internodes. Our results indicate that adaptations to mechanical strain in D. balcanica stems involve modifications in Parenchyma Cell wall structure and chemistry, which provide decreased stiffness, higher strength and increased elasticity of twisted internodes.
William A Russin - One of the best experts on this subject based on the ideXlab platform.
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modification of a specific class of plasmodesmata and loss of sucrose export ability in the sucrose export defective1 maize mutant
The Plant Cell, 1996Co-Authors: William A Russin, Ray F. Evert, Peter J Vanderveer, Thomas D Sharkey, Steven P BriggsAbstract:We report on the export capability and structural and ultrastructural characteristics of leaves of the sucrose export defective1 (sed1; formerly called sut1) maize mutant. Whole-leaf autoradiography was combined with light and transmission electron microscopy to correlate leaf structure with differences in export capacity in both wild-type and sed1 plants. Tips of sed1 blades had abnormal accumulations of starch and anthocyanin and distorted vascular tissues in the minor veins, and they did not export sucrose. Bases of sed1 blades were structurally identical to those of the wild type and did export sucrose. Electron microscopy revealed that only the plasmodesmata at the bundle sheath-vascular Parenchyma Cell interface in sed1 minor veins were structurally modified. Aberrant plasmodesmal structure at this critical interface results in a symplastic interruption and a lack of phloem-loading capability. These results clarify the pathway followed by photosynthates, the pivotal role of the plasmodesmata at the bundle sheath-vascular Parenchyma Cell interface, and the role of the vascular Parenchyma Cells in phloem loading.
