Modification of cell wall architecture of wheat coleoptiles grown under hypergravity conditions.
Cell wall structure of wheat coleoptiles grown under continuous hypergravity (300 g) conditions was investigated. Length of coleoptiles exposed to hypergravity for 2-4 days from germination stage was 60-70% of that of 1 g control. The amounts of cell wall polysaccharides substantially increased during the incubation period both in 1 g control and hypergravity-treated coleoptiles. As a results, the levels of cell wall polysaccharides per unit length of coleoptile, which mean the thickness of cell walls, largely increased under hypergravity conditions. The major sugar components of the hemicellulose fraction, a polymer fraction extracted from cell walls with strong alkali, were arabinose (Ara), xylose (Xyl) and glucose (Glc). The molar ratios of Ara and Xyl to Glc in hypergravity-treated coleoptiles were higher than those in control coleoptiles. Furthermore, the fractionation of hemicellulosic polymers into the neutral and acidic polymers by the anion-exchange column showed that the levels of acidic polymers in cell walls of hypergravity-treated coleoptiles were higher than those of control coleoptiles. These results suggest that hypergravity stimuli bias the synthesis of hemicellulosic polysaccharides and increase the proportion of acidic polymers, such as arabinoxylans, in cell walls of wheat coleoptiles. These structural changes in cell walls may contribute to plant resistance to hypergravity stimuli.
Wakabayashi
Kazuyuki
K
Graduate School of Science, Osaka City Univ.
Soga
Kouichi
K
Kamisaka
Seiichiro
S
Hoson
Takayuki
T
D001089:Arabinose / Q000378:metabolism; D002473:Cell Wall / Q000502:physiology*; D018548:Cotyledon / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D018471:Hypergravity; D011134:Polysaccharides / Q000378:metabolism; D014908:Triticum / Q000166:cytology* / Q000378:metabolism; D014994:Xylose / Q000378:metabolism
D011134:Polysaccharides; C007916:hemicellulose; D014994:Xylose; D001089:Arabinose; D005947:Glucose