PLANT PHYSIOLOGY , Vol 114, Issue 2 723-729, Copyright © 1997 by American Society of Plant Biologists
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BIOCHEMISTRY AND ENZYMOLOGY |
Turnover of Galactans and Other Cell Wall Polysaccharides during Development of Flax Plants
T. A. Gorshkova, S. B. Chemikosova, V. V. Lozovaya and N. C. Carpita
Kazan Institute of Biology, Russian Academy of Sciences, 420503, Kazan, P.O. Box 30, Russia (T.A.G., S.B.C., V.V.L.)
We investigated the synthesis and turnover of cell wall polysaccharides of
the flax (Linum usitatissimum L.) plant during development of the phloem
fibers. One-month-old flax plants were exposed to a 40-min pulse with 14CO2
followed by 8-h, 24-h, and 1-month periods of chase with ambient CO2, and
radioactivity in cell wall sugars was determined in various plant parts.
The relative radioactivity of glucose in noncellulosic polysaccharides was
the highest compared with all other cell wall sugars immediately after the
pulse and decreased substantially during the subsequent chase. The relative
radioactivities of the other cell wall sugars changed with differing rates,
indicating turnover of specific polysaccharides. Notably, after 1 month of
chase there was a marked decrease in the proportional mass and total
radioactivity in cell wall galactose, indicating a long-term turnover of
the galactans enriched in the fiber-containing tissues. The ratio of
radiolabeled xylose to arabinose also increased during the chase,
indicating a turnover of arabinose-containing polymers and interconversion
to xylose. The pattern of label redistribution differed between organs,
indicating that the cell wall turnover processes are tissue- and
cell-specific.
