Activity of cell-wall degradation associated with differentiation of isolated mesophyll cells of Zinnia elegans into tracheary elements.
Cell walls were prepared from cultured mesophyll cells of Zinnia elegans L. that were transdifferentiating into tracheary elements and incubated in a buffer to undergo autolysis. The rate of autolysis of cell walls was determined by measuring the amount of carbohydrate released from the cell walls into the buffer during incubation. During the course of culture of mesophyll cells, the autolysis rate increased markedly at the time when thickenings of secondary cell walls characteristic of tracheary elements became visible (after 48-72 h of culture), and thereafter the rate remained at a high level. Comparative studies on the autolysis rate of cell walls using various control cultures, in which tracheary element differentiation did not take place, revealed a close relationship between the autolysis rate around the 60th hour of culture and differentiation. Sugar analysis by colorimetric assays and gas chromatography of carbohydrates released from the cell walls detected uronic acid, arabinose, galactose, glucose, xylose, rhamnose, fucose, and mannose. Among these sugars, uronic acid was the most abundant, and accounted for approximately half of the total released sugars. The decrease of acidic polysaccharides in the primary cell walls during tracheary element differentiation was visualized by staining cultured cells with alcian blue at pH 2.5. These results suggest that active degradation of components of primary cell walls, including pectin, is integrated into the program of tracheary element differentiation.
Ohdaira
Youichi
Y
Biological Institute, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan. .
Kakegawa
Koichi
K
Amino
Shin-Ichi
S
Sugiyama
Munetaka
M
Fukuda
Hiroo
H
D000423:Alcian Blue; D019659:Asteraceae / Q000166:cytology / Q000378:metabolism*; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000737:chemistry; D002454:Cell Differentiation / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism*; D013194:Staining and Labeling / Q000379:methods; D013997:Time Factors
D002241:Carbohydrates; D000423:Alcian Blue