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Salinity stress inhibits calcium loading into the xylem of excised barley ( Hordeum vulgare ) roots
Author(s) -
HALPERIN STEPHEN J.,
KOCHIAN LEON V.,
LYNCH JONATHAN P.
Publication year - 1997
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.1997.00680.x
Subject(s) - apoplast , chromosomal translocation , mannitol , xylem , calcium , exudate , chemistry , hordeum vulgare , apex (geometry) , sodium , shoot , ion transporter , botany , salinity , biophysics , horticulture , biology , cell wall , biochemistry , poaceae , organic chemistry , membrane , gene , ecology
summary Salinity stress inhibits Ca translocation to the shoot, leading to Ca deficiency. The objective of this study was to determine whether salt stress inhibits Ca translocation through effects on younger root regions, where radial Ca transport is largely apoplastic, or through effects on mature regions of the roots, where radial Ca transport is largely symplastic. Roots were excised from 4‐d‐old dark‐grown barley seedlings. Calcium translocation was studied by application of 45 Ca 3 or 6 cm from the root tip and measurement of its appearance in the root exudate. Calcium uptake along the axis of excised roots was studied with a vibrating Ca +2 microelectrode. Salt stress (60 mM NaCl) inhibited Ca translocation from the 6 cm region more than from the 3 cm region. Sodium sulphate treatments (30 and 36 mM) were more deleterious to Ca translocation than was NaCl in the 3 cm region, and 110 mM mannitol and 60 mM KC1 affected Ca translocation similarly to Na 2 SO 4 . The salt and mannitol treatments were more deleterious to Ca translocation in the 6 cm region than in the 3 cm region, and mannitol and KC1 inhibited Ca translocation more than the sodium treatments. Supplemental Ca could overcome the inhibition of Ca translocation by NaCl stress. Calcium uptake into the root at the 3 and 6 cm regions was not reduced by NaCl, but was retarded 0–05 cm from the apex. We conclude that symplastic Ca transport is more inhibited than apoplastic transport in salinized roots, and that the osmotic component of salt stress causes most of the inhibition. Since symplastic transport is inhibited, the possibility exists that research into the effects of salinity on the transport functions of endodermal cells will yield information that can be used to improve Ca translocation in salt‐affected plants.