Open AccessBoron Uptake by Excised Barley Roots
Author(s) -
John E. Bowen,
P. Nissen
Publication year - 1976
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.57.3.353
Subject(s) - monosaccharide , boron , polysaccharide , chemistry , cell wall , hordeum vulgare , distilled water , stoichiometry , polyol , monomer , nuclear chemistry , chromatography , biochemistry , botany , poaceae , biology , organic chemistry , polyurethane , polymer
At 2 C, all boron accumulated by excised barley roots (Hordeum vulgare L. cv. Herta) remains in the free space; i.e. active uptake is nil at this temperature. Three component fractions of free space B were apparent: (a) a surface contaminant film of B on blotted roots, (b) water free space B, and (c) B reversibly bound in the cell walls. A stoichiometric release of H(+) from the roots in the presence of B indicated that B was bound by borate complexes with polysaccharides in the cell walls. Polysaccharide-borate complexes are much less stable than those of monosaccharides, and the bound B fraction could be readily removed by rinsing the roots in the presence of a monomeric polyol possessing the necessary cis-diol configuration. Cell wall material separated from excised barley roots had a B binding capacity 66% greater than that of intact roots.A 30-minute rinse in distilled H(2)O or 0.5 mm CaSO(4) was required to remove all cell wall-bound B from the roots after a 30-minute uptake period. Thus, although B in the contaminant surface film and the water free space is rinsed from the roots within 10 minutes, a 30-minute rinse is essential if all reversibly accumulated B is to be removed from the free space.