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Takayuki Hoson - One of the best experts on this subject based on the ideXlab platform.
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Role of Xyloglucan in gravitropic bending of azuki bean epicotyl.
Physiologia Plantarum, 2008Co-Authors: Toshimitsu Ikushima, Kouichi Soga, Takayuki Hoson, Teruo ShimmenAbstract:The mechanism of the gravitropic bending was studied in azuki bean epicotyls. The cell wall extensibility of the lower side became higher than that of the upper side in the epicotyl bending upward. The contents of matrix polysaccharides of the cell wall (pectin and Xyloglucan in hemicellulose-II) in the lower side became smaller than those in the upper side. The molecular mass of Xyloglucans in the lower side decreased. After an epicotyl was fixed to a metal rod to prevent the bending, gravistimulation was applied. Fundamentally the same results were obtained with respect to rheological and chemical characteristics of the cell wall as those of epicotyls showing gravitropic bending. The present results suggested that the initial gravitropic bending was caused by the increase in extensibility of the lower side and the decrease in extensibility of the upper side via the change of the cell wall matrix, especially Xyloglucans.
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Modifications of Xyloglucan metabolism in azuki bean epicotyls under hypergravity conditions
Advances in Space Research, 2007Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Kuninori Arai, Takayuki HosonAbstract:Abstract We examined the effects of hypergravity on both the synthesis and the depolymerization processes of Xyloglucan metabolisms. Azuki bean cuttings were incubated with [6- 3 H]- l -fucose, and the levels and the molecular size of synthesized Xyloglucans were investigated in the upper growing regions of epicotyls. The amounts of radioactivity incorporated into Xyloglucan fraction increased during incubation, irrespective of the gravity conditions. 3 H-Xyloglucans were eluted in the higher molecular mass regions than Xyloglucans already present in the cell wall. Hypergravity at 300 g did not influence the molecular size of newly deposited Xyloglucans. Thus, the process of Xyloglucan synthesis was not modified by the gravitational force. On the other hand, 3 H-Xyloglucans obtained from epicotyls grown at 1 g were shifted to the low molecular mass regions during the incubation period, which was inhibited by hypergravity. These results indicate that Xyloglucans were deposited into the cell wall as large molecules but they were then depolymerized in the cell wall, and that the inhibition of the depolymerization is mainly responsible for the increase in the molecular size of Xyloglucans under hypergravity conditions.
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Xyloglucan oligosaccharides cause cell wall loosening by enhancing Xyloglucan endotransglucosylase hydrolase activity in azuki bean epicotyls
Plant and Cell Physiology, 2004Co-Authors: Tomomi Kaku, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:;Addition of Xyloglucan-derived oligosaccharides shifted the wall-bound Xyloglucans to a lower molecular mass distribution and increased the cell wall extensibility of the native epidermal tissue strips isolated from azuki bean (Vigna angularis) epicotyls. To ascertain the mechanism of oligosaccharide function, we examined the action of a Xyloglucan endotransglucosylase/hydrolase (XTH) showing both endotransglucosylase and endohydrolase activities, isolated from azuki bean epicotyl cell walls, in the presence of Xyloglucan oligosaccharides. The addition of Xyloglucan oligosaccharides enhanced the Xyloglucan-degrading activity of XTH against isolated Xyloglucan substrates. When the methanol-fixed epidermal tissue strips were incubated with XTH, the molecular mass of wall-bound Xyloglucans was decreased and the cell wall extensibility increased markedly in the presence of the oligosaccharides. These results suggest that Xyloglucan oligosaccharides stimulate the degradation of Xyloglucans by enhancing the XTH activity within the cell wall architecture, thereby increasing the cell wall extensibility in azuki bean epicotyls.
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Xyloglucan Oligosaccharides Cause Cell Wall Loosening by Enhancing Xyloglucan Endotransglucosylase/Hydrolase Activity in Azuki Bean Epicotyls
Plant & cell physiology, 2004Co-Authors: Tomomi Kaku, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:;Addition of Xyloglucan-derived oligosaccharides shifted the wall-bound Xyloglucans to a lower molecular mass distribution and increased the cell wall extensibility of the native epidermal tissue strips isolated from azuki bean (Vigna angularis) epicotyls. To ascertain the mechanism of oligosaccharide function, we examined the action of a Xyloglucan endotransglucosylase/hydrolase (XTH) showing both endotransglucosylase and endohydrolase activities, isolated from azuki bean epicotyl cell walls, in the presence of Xyloglucan oligosaccharides. The addition of Xyloglucan oligosaccharides enhanced the Xyloglucan-degrading activity of XTH against isolated Xyloglucan substrates. When the methanol-fixed epidermal tissue strips were incubated with XTH, the molecular mass of wall-bound Xyloglucans was decreased and the cell wall extensibility increased markedly in the presence of the oligosaccharides. These results suggest that Xyloglucan oligosaccharides stimulate the degradation of Xyloglucans by enhancing the XTH activity within the cell wall architecture, thereby increasing the cell wall extensibility in azuki bean epicotyls.
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Xyloglucan breakdown during cotton fiber development
Journal of plant physiology, 2003Co-Authors: Hayato Tokumoto, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Cotton (Gossypium herbaceum L.) fibers elongated almost linearly up to about 20 days post anthesis. The molecular mass of Xyloglucans in fiber cell walls decreased gradually during the elongation stage. When enzymatically active (native) cell wall preparations of fibers were autolyzed, the molecular mass of Xyloglucans decreased. The decrease was most prominent in wall preparations obtained from the rapidly elongating fibers. The Xyloglucan-degrading activity was recovered from the fiber cell walls with 3 mol/L NaCl, and the activity was high at the stages in which fibers elongated vigorously. These results suggest the possible involvement of Xyloglucan metabolism in the regulation of cotton fiber elongation.
Seiichiro Kamisaka - One of the best experts on this subject based on the ideXlab platform.
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Modifications of Xyloglucan metabolism in azuki bean epicotyls under hypergravity conditions
Advances in Space Research, 2007Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Kuninori Arai, Takayuki HosonAbstract:Abstract We examined the effects of hypergravity on both the synthesis and the depolymerization processes of Xyloglucan metabolisms. Azuki bean cuttings were incubated with [6- 3 H]- l -fucose, and the levels and the molecular size of synthesized Xyloglucans were investigated in the upper growing regions of epicotyls. The amounts of radioactivity incorporated into Xyloglucan fraction increased during incubation, irrespective of the gravity conditions. 3 H-Xyloglucans were eluted in the higher molecular mass regions than Xyloglucans already present in the cell wall. Hypergravity at 300 g did not influence the molecular size of newly deposited Xyloglucans. Thus, the process of Xyloglucan synthesis was not modified by the gravitational force. On the other hand, 3 H-Xyloglucans obtained from epicotyls grown at 1 g were shifted to the low molecular mass regions during the incubation period, which was inhibited by hypergravity. These results indicate that Xyloglucans were deposited into the cell wall as large molecules but they were then depolymerized in the cell wall, and that the inhibition of the depolymerization is mainly responsible for the increase in the molecular size of Xyloglucans under hypergravity conditions.
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Xyloglucan breakdown during cotton fiber development
Journal of plant physiology, 2003Co-Authors: Hayato Tokumoto, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Cotton (Gossypium herbaceum L.) fibers elongated almost linearly up to about 20 days post anthesis. The molecular mass of Xyloglucans in fiber cell walls decreased gradually during the elongation stage. When enzymatically active (native) cell wall preparations of fibers were autolyzed, the molecular mass of Xyloglucans decreased. The decrease was most prominent in wall preparations obtained from the rapidly elongating fibers. The Xyloglucan-degrading activity was recovered from the fiber cell walls with 3 mol/L NaCl, and the activity was high at the stages in which fibers elongated vigorously. These results suggest the possible involvement of Xyloglucan metabolism in the regulation of cotton fiber elongation.
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stimulation of elongation growth and Xyloglucan breakdown in arabidopsis hypocotyls under microgravity conditions in space
Planta, 2002Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Seedlings of Arabidopsis thaliana (L.) Heynh. (ecotype Columbia and an ethylene-resistant mutant etr1-1) were cultivated for 68.5, 91.5 and 136 h on board during the Space Shuttle STS-95 mission, and changes in the elongation growth and the cell wall properties of hypocotyls were analyzed. Elongation growth of dark-grown hypocotyls of both Columbia and etr1-1 was stimulated under microgravity conditions in space. There were no clear differences in the degree of growth stimulation between Columbia and etr1-1, indicating that the ethylene level was not abnormally high in the cultural environment of this space experiment. Microgravity also increased the mechanical extensibility of cell walls in both cultivars, and such an increase was attributed to the increase in the apparent irreversible extensibility. The levels of cell wall polysaccharides per unit length of hypocotyls decreased in space. Microgravity also reduced the weight-average molecular mass of Xyloglucans in the hemicellulose-II fraction. Also, the activity of Xyloglucan-degrading enzymes extracted from hypocotyl cell walls increased under microgravity conditions. These results suggest that microgravity reduces the molecular mass of Xyloglucans by increasing Xyloglucan-degrading activity. Modifications of Xyloglucan metabolism as well as the thickness of cell wall polysaccharides seem to be involved in an increase in the cell wall extensibility, leading to growth stimulation of Arabidopsis hypocotyls in space.
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action of Xyloglucan hydrolase within the native cell wall architecture and its effect on cell wall extensibility in azuki bean epicotyls
Plant and Cell Physiology, 2002Co-Authors: Tomomi Kaku, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:Xyloglucan hydrolase (XGH) has recently been purified from the cell wall of azuki bean (Vigna angularis Ohwi et Ohashi) epicotyls as a new type of Xyloglucan-degrading enzyme [Tabuchi et al. (2001) Plant Cell Physiol. 42: 154]. In the present study, the effects of XGH on the mechanical properties of the cell wall and on the level and the molecular size of Xyloglucans within the native wall architecture were examined in azuki bean epicotyls. When the epidermal tissue strips from the growing regions of azuki bean epicotyls were incubated with XGH, the mechanical extensibility of the cell wall dramatically increased. XGH exogenously applied to cell wall materials (homogenates) or epidermal tissue strips decreased the amount of Xyloglucans via the solubilization of the polysaccharides. Also, XGH substantially decreased the molecular mass of Xyloglucans in both materials. These results indicate that XGH is capable of hydrolyzing Xyloglucans within the native cell wall architecture and thereby increasing the cell wall extensibility in azuki bean epicotyls.
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a new type of endo Xyloglucan transferase devoted to Xyloglucan hydrolysis in the cell wall of azuki bean epicotyls
Plant and Cell Physiology, 2001Co-Authors: Akira Tabuchi, Seiichiro Kamisaka, Hitoshi Mori, Takayuki HosonAbstract:;A new type of Xyloglucan-degrading enzyme was isolated from the cell wall of azuki bean (Vigna angularis Ohwi et Ohashi cv. Takara) epicotyls and its characteristics were determined. The enzyme was purified to apparent homogeneity by Concanavalin A (Con A)-Sepharose, cation exchange, and gel filtration columns from a cell wall protein fraction extracted with 1 M sodium chloride. The purified enzyme gave a single protein band of 33 kDa on SDS-PAGE. The enzyme specifically cleaved Xyloglucans and showed maximum activity at pH 5.0 when assayed by the iodine-staining method. An increase in reducing power in Xyloglucan solution was clearly detected after treatment with the purified enzyme. Xyloglucans with molecular masses of 500 and 25 kDa were gradually hydrolyzed to 5 kDa for 96 h without production of any oligo- or monosaccharide with the purified enzyme. The purified enzyme did not show an endo-type transglycosylation reaction, even in the presence of Xyloglucan oligosaccharides. Partial amino acid sequences of the enzyme shared an identity with endo-Xyloglucan transferase (EXGT) family, especially with Xyloglucan endotransglycosylase (XET) from nasturtium. These results suggest that the enzyme is a new member of EXGT devoted solely to Xyloglucan hydrolysis.
Kazuyuki Wakabayashi - One of the best experts on this subject based on the ideXlab platform.
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Modifications of Xyloglucan metabolism in azuki bean epicotyls under hypergravity conditions
Advances in Space Research, 2007Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Kuninori Arai, Takayuki HosonAbstract:Abstract We examined the effects of hypergravity on both the synthesis and the depolymerization processes of Xyloglucan metabolisms. Azuki bean cuttings were incubated with [6- 3 H]- l -fucose, and the levels and the molecular size of synthesized Xyloglucans were investigated in the upper growing regions of epicotyls. The amounts of radioactivity incorporated into Xyloglucan fraction increased during incubation, irrespective of the gravity conditions. 3 H-Xyloglucans were eluted in the higher molecular mass regions than Xyloglucans already present in the cell wall. Hypergravity at 300 g did not influence the molecular size of newly deposited Xyloglucans. Thus, the process of Xyloglucan synthesis was not modified by the gravitational force. On the other hand, 3 H-Xyloglucans obtained from epicotyls grown at 1 g were shifted to the low molecular mass regions during the incubation period, which was inhibited by hypergravity. These results indicate that Xyloglucans were deposited into the cell wall as large molecules but they were then depolymerized in the cell wall, and that the inhibition of the depolymerization is mainly responsible for the increase in the molecular size of Xyloglucans under hypergravity conditions.
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Xyloglucan Oligosaccharides Cause Cell Wall Loosening by Enhancing Xyloglucan Endotransglucosylase/Hydrolase Activity in Azuki Bean Epicotyls
Plant & cell physiology, 2004Co-Authors: Tomomi Kaku, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:;Addition of Xyloglucan-derived oligosaccharides shifted the wall-bound Xyloglucans to a lower molecular mass distribution and increased the cell wall extensibility of the native epidermal tissue strips isolated from azuki bean (Vigna angularis) epicotyls. To ascertain the mechanism of oligosaccharide function, we examined the action of a Xyloglucan endotransglucosylase/hydrolase (XTH) showing both endotransglucosylase and endohydrolase activities, isolated from azuki bean epicotyl cell walls, in the presence of Xyloglucan oligosaccharides. The addition of Xyloglucan oligosaccharides enhanced the Xyloglucan-degrading activity of XTH against isolated Xyloglucan substrates. When the methanol-fixed epidermal tissue strips were incubated with XTH, the molecular mass of wall-bound Xyloglucans was decreased and the cell wall extensibility increased markedly in the presence of the oligosaccharides. These results suggest that Xyloglucan oligosaccharides stimulate the degradation of Xyloglucans by enhancing the XTH activity within the cell wall architecture, thereby increasing the cell wall extensibility in azuki bean epicotyls.
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Xyloglucan oligosaccharides cause cell wall loosening by enhancing Xyloglucan endotransglucosylase hydrolase activity in azuki bean epicotyls
Plant and Cell Physiology, 2004Co-Authors: Tomomi Kaku, Kazuyuki Wakabayashi, Akira Tabuchi, Takayuki HosonAbstract:;Addition of Xyloglucan-derived oligosaccharides shifted the wall-bound Xyloglucans to a lower molecular mass distribution and increased the cell wall extensibility of the native epidermal tissue strips isolated from azuki bean (Vigna angularis) epicotyls. To ascertain the mechanism of oligosaccharide function, we examined the action of a Xyloglucan endotransglucosylase/hydrolase (XTH) showing both endotransglucosylase and endohydrolase activities, isolated from azuki bean epicotyl cell walls, in the presence of Xyloglucan oligosaccharides. The addition of Xyloglucan oligosaccharides enhanced the Xyloglucan-degrading activity of XTH against isolated Xyloglucan substrates. When the methanol-fixed epidermal tissue strips were incubated with XTH, the molecular mass of wall-bound Xyloglucans was decreased and the cell wall extensibility increased markedly in the presence of the oligosaccharides. These results suggest that Xyloglucan oligosaccharides stimulate the degradation of Xyloglucans by enhancing the XTH activity within the cell wall architecture, thereby increasing the cell wall extensibility in azuki bean epicotyls.
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Xyloglucan breakdown during cotton fiber development
Journal of plant physiology, 2003Co-Authors: Hayato Tokumoto, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Cotton (Gossypium herbaceum L.) fibers elongated almost linearly up to about 20 days post anthesis. The molecular mass of Xyloglucans in fiber cell walls decreased gradually during the elongation stage. When enzymatically active (native) cell wall preparations of fibers were autolyzed, the molecular mass of Xyloglucans decreased. The decrease was most prominent in wall preparations obtained from the rapidly elongating fibers. The Xyloglucan-degrading activity was recovered from the fiber cell walls with 3 mol/L NaCl, and the activity was high at the stages in which fibers elongated vigorously. These results suggest the possible involvement of Xyloglucan metabolism in the regulation of cotton fiber elongation.
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stimulation of elongation growth and Xyloglucan breakdown in arabidopsis hypocotyls under microgravity conditions in space
Planta, 2002Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Seedlings of Arabidopsis thaliana (L.) Heynh. (ecotype Columbia and an ethylene-resistant mutant etr1-1) were cultivated for 68.5, 91.5 and 136 h on board during the Space Shuttle STS-95 mission, and changes in the elongation growth and the cell wall properties of hypocotyls were analyzed. Elongation growth of dark-grown hypocotyls of both Columbia and etr1-1 was stimulated under microgravity conditions in space. There were no clear differences in the degree of growth stimulation between Columbia and etr1-1, indicating that the ethylene level was not abnormally high in the cultural environment of this space experiment. Microgravity also increased the mechanical extensibility of cell walls in both cultivars, and such an increase was attributed to the increase in the apparent irreversible extensibility. The levels of cell wall polysaccharides per unit length of hypocotyls decreased in space. Microgravity also reduced the weight-average molecular mass of Xyloglucans in the hemicellulose-II fraction. Also, the activity of Xyloglucan-degrading enzymes extracted from hypocotyl cell walls increased under microgravity conditions. These results suggest that microgravity reduces the molecular mass of Xyloglucans by increasing Xyloglucan-degrading activity. Modifications of Xyloglucan metabolism as well as the thickness of cell wall polysaccharides seem to be involved in an increase in the cell wall extensibility, leading to growth stimulation of Arabidopsis hypocotyls in space.
Kouichi Soga - One of the best experts on this subject based on the ideXlab platform.
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Role of Xyloglucan in gravitropic bending of azuki bean epicotyl.
Physiologia Plantarum, 2008Co-Authors: Toshimitsu Ikushima, Kouichi Soga, Takayuki Hoson, Teruo ShimmenAbstract:The mechanism of the gravitropic bending was studied in azuki bean epicotyls. The cell wall extensibility of the lower side became higher than that of the upper side in the epicotyl bending upward. The contents of matrix polysaccharides of the cell wall (pectin and Xyloglucan in hemicellulose-II) in the lower side became smaller than those in the upper side. The molecular mass of Xyloglucans in the lower side decreased. After an epicotyl was fixed to a metal rod to prevent the bending, gravistimulation was applied. Fundamentally the same results were obtained with respect to rheological and chemical characteristics of the cell wall as those of epicotyls showing gravitropic bending. The present results suggested that the initial gravitropic bending was caused by the increase in extensibility of the lower side and the decrease in extensibility of the upper side via the change of the cell wall matrix, especially Xyloglucans.
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Modifications of Xyloglucan metabolism in azuki bean epicotyls under hypergravity conditions
Advances in Space Research, 2007Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Kuninori Arai, Takayuki HosonAbstract:Abstract We examined the effects of hypergravity on both the synthesis and the depolymerization processes of Xyloglucan metabolisms. Azuki bean cuttings were incubated with [6- 3 H]- l -fucose, and the levels and the molecular size of synthesized Xyloglucans were investigated in the upper growing regions of epicotyls. The amounts of radioactivity incorporated into Xyloglucan fraction increased during incubation, irrespective of the gravity conditions. 3 H-Xyloglucans were eluted in the higher molecular mass regions than Xyloglucans already present in the cell wall. Hypergravity at 300 g did not influence the molecular size of newly deposited Xyloglucans. Thus, the process of Xyloglucan synthesis was not modified by the gravitational force. On the other hand, 3 H-Xyloglucans obtained from epicotyls grown at 1 g were shifted to the low molecular mass regions during the incubation period, which was inhibited by hypergravity. These results indicate that Xyloglucans were deposited into the cell wall as large molecules but they were then depolymerized in the cell wall, and that the inhibition of the depolymerization is mainly responsible for the increase in the molecular size of Xyloglucans under hypergravity conditions.
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stimulation of elongation growth and Xyloglucan breakdown in arabidopsis hypocotyls under microgravity conditions in space
Planta, 2002Co-Authors: Kouichi Soga, Seiichiro Kamisaka, Kazuyuki Wakabayashi, Takayuki HosonAbstract:Seedlings of Arabidopsis thaliana (L.) Heynh. (ecotype Columbia and an ethylene-resistant mutant etr1-1) were cultivated for 68.5, 91.5 and 136 h on board during the Space Shuttle STS-95 mission, and changes in the elongation growth and the cell wall properties of hypocotyls were analyzed. Elongation growth of dark-grown hypocotyls of both Columbia and etr1-1 was stimulated under microgravity conditions in space. There were no clear differences in the degree of growth stimulation between Columbia and etr1-1, indicating that the ethylene level was not abnormally high in the cultural environment of this space experiment. Microgravity also increased the mechanical extensibility of cell walls in both cultivars, and such an increase was attributed to the increase in the apparent irreversible extensibility. The levels of cell wall polysaccharides per unit length of hypocotyls decreased in space. Microgravity also reduced the weight-average molecular mass of Xyloglucans in the hemicellulose-II fraction. Also, the activity of Xyloglucan-degrading enzymes extracted from hypocotyl cell walls increased under microgravity conditions. These results suggest that microgravity reduces the molecular mass of Xyloglucans by increasing Xyloglucan-degrading activity. Modifications of Xyloglucan metabolism as well as the thickness of cell wall polysaccharides seem to be involved in an increase in the cell wall extensibility, leading to growth stimulation of Arabidopsis hypocotyls in space.
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gravitational force regulates elongation growth of arabidopsis hypocotyls by modifying Xyloglucan metabolism
Advances in Space Research, 2001Co-Authors: Kouichi Soga, Kazuyuki Wakabayashi, Takayuki Hoson, Seiichiro KamisakaAbstract:Abstract Growth of dark-grown Arabidopsis hypocotyls was suppressed under hypergravity conditions (300 g ), or was stimulated under microgravity conditions in space (Space Shuttle STS-95). The mechanical extensibility of cell walls decreased and increased under hypergravity and microgravity conditions, respectively. The amounts of cell wall polysaccharides (pectin, hemicellulose-I, hemicellulose-II and cellulose) per unit length of hypocotyls increased under hypergravity conditions, and decreased under microgravity conditions. The amount and the molecular mass of Xyloglucans also increased under the hypergravity conditions, while those decreased under microgravity conditions. The activity of Xyloglucan-degrading enzymes extracted from hypocotyl cell walls decreased and increased under hypergravity and microgravity conditions, respectively. These results indicate that the amount and the molecular mass of Xyloglucans are affected by the magnitude of gravity and that such changes are caused by changes in Xyloglucan-degrading activity. Modifications of Xyloglucan metabolism as well as the thickness of cell walls by gravity stimulus may be the primary event determining the cell wall extensibility, thereby regulating the growth rate of Arabidopsis hypocotyls.
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Changes in the apoplastic pH are involved in regulation of Xyloglucan breakdown of azuki bean epicotyls under hypergravity conditions.
Plant and Cell Physiology, 2000Co-Authors: Kouichi Soga, Kazuyuki Wakabayashi, Takayuki Hoson, Seiichiro KamisakaAbstract:Hypergravity inhibited elongation growth of azuki bean (Vigna angularis Ohwi et Ohashi) epicotyls by decreasing the mechanical extensibility of cell walls via the increase in the molecular mass of Xyloglucans [Soga et al. (1999) Plant Cell Physiol. 40: 581]. Here, we report that the pH value of the apoplastic fluid in epicotyls increased from 5.8 to 6.6 by hypergravity (300 *g) treatment. When the Xyloglucan-degrading enzymes extracted from cell walls of the 1 x g control epicotyls were assayed in buffer at pH 6.6 and 5.8, the activity at pH 6.6 was almost half of that at pH 5.8. In addition, when enzymically active cell wall preparations obtained from lx # control epicotyls were autolyzed in buffer at pH 5.8 and 6.6 and then Xyloglucans were extracted from the autolyzed cell walls, the molecular mass of Xyloglucans incubated at pH 5.8 decreased during the autolysis, while that at pH 6.6 did not change. Thus, the Xyloglucans were not depolymerized by autolysis at the pH value (6.6) observed in the hypergravity-treated epicotyls. These findings suggest that in azuki bean epicotyls, hypergravity decreases the activities of Xyloglucan-degrading enzymes by increasing the pH in the apoplastic fluid, which may be involved in the processes of the increase in the molecular mass of Xyloglucans, leading to the decrease in the cell wall extensibility.
William S. York - One of the best experts on this subject based on the ideXlab platform.
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Generation and structural validation of a library of diverse Xyloglucan-derived oligosaccharides, including an update on Xyloglucan nomenclature
Carbohydrate research, 2014Co-Authors: Sami T. Tuomivaara, Malcolm A. O'neill, Katsuro Yaoi, William S. YorkAbstract:Abstract Xyloglucans are structurally complex plant cell wall polysaccharides that are involved in cell growth and expansion, energy metabolism, and signaling. Determining the structure–function relationships of Xyloglucans would benefit from the availability of a comprehensive and structurally diverse collection of rigorously characterized Xyloglucan oligosaccharides. Here, we present a workflow for the semi-preparative scale generation and purification of neutral and acidic Xyloglucan oligosaccharides using a combination of enzymatic and chemical treatments and size-exclusion chromatography. Twenty-six of these oligosaccharides were purified to near homogeneity and their structures validated using a combination of matrix-assisted laser desorption/ionization mass spectrometry, high-performance anion exchange chromatography, and 1H nuclear magnetic resonance spectroscopy. Mass spectrometry and analytical chromatography were compared as methods for Xyloglucan oligosaccharide quantification. 1H chemical shifts were assigned using two-dimensional correlation spectroscopy. A comprehensive update of the nomenclature describing Xyloglucan side-chain structures is provided for reference.
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a galacturonic acid containing Xyloglucan is involved in arabidopsis root hair tip growth
The Plant Cell, 2012Co-Authors: Maria J. Peña, William S. York, Yingzhen Kong, Malcolm A OneillAbstract:Root hairs provide a model system to study plant cell growth, yet little is known about the polysaccharide compositions of their walls or the role of these polysaccharides in wall expansion. We report that Arabidopsis thaliana root hair walls contain a previously unidentified Xyloglucan that is composed of both neutral and galacturonic acid–containing subunits, the latter containing the β-d-galactosyluronic acid-(1→2)-α-d-xylosyl-(1→ and/or α-l-fucosyl-(1→2)-β-d-galactosyluronic acid-(1→2)-α-d-xylosyl-(1→) side chains. Arabidopsis mutants lacking root hairs have no acidic Xyloglucan. A loss-of-function mutation in At1g63450, a root hair–specific gene encoding a family GT47 glycosyltransferase, results in the synthesis of Xyloglucan that lacks galacturonic acid. The root hairs of this mutant are shorter than those of the wild type. This mutant phenotype and the absence of galacturonic acid in the root Xyloglucan are complemented by At1g63450. The leaf and stem cell walls of wild-type Arabidopsis contain no acidic Xyloglucan. However, overexpression of At1g63450 led to the synthesis of galacturonic acid–containing Xyloglucan in these tissues. We propose that At1g63450 encodes Xyloglucan-SPECIFIC GALACTURONOSYLTRANSFERASE1, which catalyzes the formation of the galactosyluronic acid-(1→2)-α-d-xylopyranosyl linkage and that the acidic Xyloglucan is present only in root hair cell walls. The role of the acidic Xyloglucan in root hair tip growth is discussed.
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Moss and liverwort Xyloglucans contain galacturonic acid and are structurally distinct from the Xyloglucans synthesized by hornworts and vascular plants
Glycobiology, 2008Co-Authors: Maria J. Peña, Alan G. Darvill, William S. York, Stefan Eberhard, Malcolm A. O'neillAbstract:Xyloglucan is a well-characterized hemicellulosic polysaccharide that is present in the cell walls of all seed-bearing plants. The cell walls of avascular and seedless vascular plants are also believed to contain Xyloglucan. However, these Xyloglucans have not been structurally characterized. This lack of information is an impediment to understanding changes in Xyloglucan structure that occurred during land plant evolution. In this study, Xyloglucans were isolated from the walls of avascular (liverworts, mosses, and hornworts) and seedless vascular plants (club and spike mosses and ferns and fern allies). Each Xyloglucan was fragmented with a Xyloglucan-specific endo-glucanase and the resulting oligosaccharides then structurally characterized using NMR spectroscopy, MALDI-TOF and electrospray mass spectrometry, and glycosyl-linkage and glycosyl residue composition analyses. Our data show that Xyloglucan is present in the cell walls of all major divisions of land plants and that these Xyloglucans have several common structural motifs. However, these polysaccharides are not identical because specific plant groups synthesize Xyloglucans with unique structural motifs. For example, the moss Physcomitrella patens and the liverwort Marchantia polymorpha synthesize XXGGG- and XXGG-type Xyloglucans, respectively, with sidechains that contain a beta-D-galactosyluronic acid and a branched xylosyl residue. By contrast, hornworts synthesize XXXG-type Xyloglucans that are structurally homologous to the Xyloglucans synthesized by many seed-bearing and seedless vascular plants. Our results increase our understanding of the evolution, diversity, and function of structural motifs in land-plant Xyloglucans and provide support to the proposal that hornworts are sisters to the vascular plants.
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Structural analysis of Xyloglucans in the primary cell walls of plants in the subclass Asteridae
Carbohydrate Research, 2005Co-Authors: Matt Hoffman, Zhonghua Jia, Maria J. Peña, Michael T. Cash, April D. Harper, Alan R. Blackburn, Alan G. Darvill, William S. YorkAbstract:The structures of Xyloglucans from several plants in the subclass Asteridae were examined to determine how their structures vary in different taxonomic orders. Xyloglucans, solubilized from plant cell walls by a sequential (enzymatic and chemical) extraction procedure, were isolated, and their structures were characterized by NMR spectroscopy and mass spectrometry. All campanulids examined, including Lactuca sativa (lettuce, order Asterales), Tenacetum ptarmiciflorum (dusty miller, order Asterales), and Daucus carota (carrot, order Apiales), produce typical Xyloglucans that have an XXXG-type branching pattern and contain alpha-d-Xylp-, beta-D-Galp-(1-->2)-alpha-D-Xylp-, and alpha-L-Fucp-(1-->2)-beta-D-Galp-(1-->2)-alpha-D-Xylp- side chains. However, the lamiids produce atypical Xyloglucans. For example, previous analyses showed that Capsicum annum (pepper) and Lycopersicon esculentum (tomato), two species in the order Solanales, and Olea europaea (olive, order Lamiales) produce Xyloglucans that contain arabinosyl and galactosyl residues, but lack fucosyl residues. The XXGG-type Xyloglucans produced by Solanaceous species are less branched than the XXXG-type Xyloglucan produced by Olea europaea. This study shows that Ipomoea pupurea (morning glory, order Solanales), Ocimum basilicum (basil, order Lamiales), and Plantago major (plantain, order Lamiales) all produce Xyloglucans that lack fucosyl residues and have an unusual XXGGG-type branching pattern in which the basic repeating core contains five glucose subunits in the backbone. Furthermore, Neruim oleander (order Gentianales) produces an XXXG-type Xyloglucan that contains arabinosyl, galactosyl, and fucosyl residues. The appearance of this intermediate Xyloglucan structure in oleander has implications regarding the evolutionary development of Xyloglucan structure and its role in primary plant cell walls.
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Changes in the structure of Xyloglucan during cell elongation.
Planta, 2001Co-Authors: Markus Pauly, Alan G. Darvill, Qiang Qin, Henry Greene, Peter Albersheim, William S. YorkAbstract:Xyloglucans were isolated by sequential extraction of the cell walls of pea (Pisum sativum L. cv. Alaska) with a Xyloglucan-specific endoglucanase and KOH. The Xyloglucan content and Xyloglucan-oligosaccharide composition were determined for fractions obtained from the elongating and non-elongating segments of pea stems grown in the light and in darkness. The results were consistent with the hypothesis that regulated growth of the cell wall depends on Xyloglucan metabolism. Furthermore, the characterization of Xyloglucan extracted from leaves of light-grown pea plants indicates that Xyloglucan metabolism is tissue specific. Changes in Xyloglucan subunit structure observed in elongating stems are consistent with the in muro realization of a metabolic pathway that was previously proposed solely on the basis of the in vitro activities of plant glycosyl hydrolases.
