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Ken Sasaki, Iain E. P. Taylor, Specific Labeling of Cell Wall Polysaccharides with myo-[2-3H] Inositol during Germination and Growth of Phaseolus vulgaris L., Plant and Cell Physiology, Volume 25, Issue 6, September 1984, Pages 989–997, https://doi.org/10.1093/oxfordjournals.pcp.a076815
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Abstract
myo-[2-3H]Inositol was fed to bean seeds by imbibition and its metabolic fate was studied during germination and seedling growth. The largest amount of myo-inositol was taken up from a 500 HIM supply (8 mg/seed) and the highest percentage was from 1 HIM (29%). myo-Inositol was incorporated to new cell wall polysaccharides of hypocotyl and roots, mostly as uronic acid and pentose residues. In the 80% ethanolinsoluble cell walls of hypocotyls at 3, 4 and 5 days after imbibition, 47 to 52% of 3H was detected as uronic acids, 20 to 24% as arabinose and 11 to 19% as xylose. Glucogenesis from myo-inositol was low: less than 6% was recovered as hexoses. The 3H in uronic acid and arabinose residues decreased with increasing age (i.e. 0 to 6 cm from cotyledons) and increased in older segments (further than 6 cm from cotyledons). In the oldest segment of 5-day-old hypocotyl (> 10 cm), 3H in the sugar residues was more than that in the youngest part (0–2 cm). On the other hand, 3H in xylose residues increased steadily in the older part, but did not exceed that in arabinose.
The results show that the myo-inositol oxidation pathway functions in growing hypocotyls and roots of bean seedlings to provide exclusively uronic acid and pentose units for cell wall synthesis. Results also show that incorporation of arabinose and uronic acids derived from myo-[2-3H]inositol to cell wall polysaccharides is active in two regions of the hypocotyl; first, for the construction of the primary walls in the young, growing region of the hypocotyl, and second, for thickening of the walls after completion of elongation growth.
