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Effects of non-uniform root zone salinity on water use, Na+ recirculation, and Na+ and H+ flux in cotton.

Kong X, Luo Z, Dong H, Eneji AE, Li W - J. Exp. Bot. (2011)

Bottom Line: Non-uniform treatments decreased Na(+) concentrations in leaves.The [Na(+)] in the '0' side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the '0' side phloem was girdled, suggesting that the increased [Na(+)] in the '0' side roots was possibly due to transportation of foliar Na(+) to roots through phloem.Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na(+) concentration, transport of excessive foliar Na(+) to the low salinity side, and enhanced Na(+) efflux from the low salinity root.

View Article: PubMed Central - PubMed

Affiliation: Shandong Academy of Agricultural Sciences, Jinan, People's Republic of China.

ABSTRACT
A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100 mM) or non-uniform NaCl concentrations (0/200 and 50/150 mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na(+) concentrations in leaves. The [Na(+)] in the '0' side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the '0' side phloem was girdled, suggesting that the increased [Na(+)] in the '0' side roots was possibly due to transportation of foliar Na(+) to roots through phloem. Plants under non-uniform salinity extruded more Na(+) from the root than those under uniform salinity. Root Na(+) efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na(+) efflux and H(+) influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na(+) extrusion was probably due to active Na(+)/H(+) antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na(+) concentration, transport of excessive foliar Na(+) to the low salinity side, and enhanced Na(+) efflux from the low salinity root.

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The K+ concentration in the third main stem leaves (A); roots (B), xylem, (D), and phloem (G) of the low salt side; roots (C), xylem, (E), and phloem (H) of the high salt side, and xylem (F) and phloem (I) of the stem at 1, 3, and 7 d after 0/0, 0/200, 50/150, and 100/100 mM NaCl treatment. Values are means ±SE (n=6).
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fig5: The K+ concentration in the third main stem leaves (A); roots (B), xylem, (D), and phloem (G) of the low salt side; roots (C), xylem, (E), and phloem (H) of the high salt side, and xylem (F) and phloem (I) of the stem at 1, 3, and 7 d after 0/0, 0/200, 50/150, and 100/100 mM NaCl treatment. Values are means ±SE (n=6).

Mentions: The Na+ and K+ concentrations in leaves, roots, xylem, and phloem of the stems and hypocotyls were measured at 1, 3, and 7 d after treatment (Figs 4, 5). As Na+ and K+ concentrations were not significantly different between two hypocotyls as well as roots of plants under uniform salinity (0/0 mM and 100/100 mM NaCl), the data presented are pooled averages (Figs 4, 5). The Na+ concentration in leaves, roots, xylem, and phloem of the stems increased with increasing NaCl treatment time and concentrations (Fig. 4). Compared with uniform salinity (100/100 mM NaCl), non-uniform salinity (0/200 mM and 50/150 mM NaCl) decreased the Na+ concentration in the leaves (Fig. 4A), xylem, and phloem (stem) (Fig. 4F, I). The Na+ concentration in the root, hypocotyls xylem and phloem on the ‘0’ side in the 0/200 treatment was similar to that on either side in 0/0 at 1 d and 3 d after treatment (Fig. 4B, D, G). However, the Na+ concentration on the ‘0’ side increased by 91.7, 50.9, and 43.4 %, respectively, compared with either side in the 0/0 treatment at 7 d after NaCl treatment (Fig. 4B, D, G). Under NaCl treatments, the Na+ concentration in the xylem and phloem of the high salt side was much higher than that in the stem (Fig. 4E, F, H, I). The Na+ concentration in the phloem was ∼1.2-fold higher than in the xylem under 0/0 mM NaCl treatment and ∼1.6-fold higher under NaCl treatments (data not shown).


Effects of non-uniform root zone salinity on water use, Na+ recirculation, and Na+ and H+ flux in cotton.

Kong X, Luo Z, Dong H, Eneji AE, Li W - J. Exp. Bot. (2011)

The K+ concentration in the third main stem leaves (A); roots (B), xylem, (D), and phloem (G) of the low salt side; roots (C), xylem, (E), and phloem (H) of the high salt side, and xylem (F) and phloem (I) of the stem at 1, 3, and 7 d after 0/0, 0/200, 50/150, and 100/100 mM NaCl treatment. Values are means ±SE (n=6).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3295398&req=5

fig5: The K+ concentration in the third main stem leaves (A); roots (B), xylem, (D), and phloem (G) of the low salt side; roots (C), xylem, (E), and phloem (H) of the high salt side, and xylem (F) and phloem (I) of the stem at 1, 3, and 7 d after 0/0, 0/200, 50/150, and 100/100 mM NaCl treatment. Values are means ±SE (n=6).
Mentions: The Na+ and K+ concentrations in leaves, roots, xylem, and phloem of the stems and hypocotyls were measured at 1, 3, and 7 d after treatment (Figs 4, 5). As Na+ and K+ concentrations were not significantly different between two hypocotyls as well as roots of plants under uniform salinity (0/0 mM and 100/100 mM NaCl), the data presented are pooled averages (Figs 4, 5). The Na+ concentration in leaves, roots, xylem, and phloem of the stems increased with increasing NaCl treatment time and concentrations (Fig. 4). Compared with uniform salinity (100/100 mM NaCl), non-uniform salinity (0/200 mM and 50/150 mM NaCl) decreased the Na+ concentration in the leaves (Fig. 4A), xylem, and phloem (stem) (Fig. 4F, I). The Na+ concentration in the root, hypocotyls xylem and phloem on the ‘0’ side in the 0/200 treatment was similar to that on either side in 0/0 at 1 d and 3 d after treatment (Fig. 4B, D, G). However, the Na+ concentration on the ‘0’ side increased by 91.7, 50.9, and 43.4 %, respectively, compared with either side in the 0/0 treatment at 7 d after NaCl treatment (Fig. 4B, D, G). Under NaCl treatments, the Na+ concentration in the xylem and phloem of the high salt side was much higher than that in the stem (Fig. 4E, F, H, I). The Na+ concentration in the phloem was ∼1.2-fold higher than in the xylem under 0/0 mM NaCl treatment and ∼1.6-fold higher under NaCl treatments (data not shown).

Bottom Line: Non-uniform treatments decreased Na(+) concentrations in leaves.The [Na(+)] in the '0' side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the '0' side phloem was girdled, suggesting that the increased [Na(+)] in the '0' side roots was possibly due to transportation of foliar Na(+) to roots through phloem.Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na(+) concentration, transport of excessive foliar Na(+) to the low salinity side, and enhanced Na(+) efflux from the low salinity root.

View Article: PubMed Central - PubMed

Affiliation: Shandong Academy of Agricultural Sciences, Jinan, People's Republic of China.

ABSTRACT
A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100 mM) or non-uniform NaCl concentrations (0/200 and 50/150 mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na(+) concentrations in leaves. The [Na(+)] in the '0' side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the '0' side phloem was girdled, suggesting that the increased [Na(+)] in the '0' side roots was possibly due to transportation of foliar Na(+) to roots through phloem. Plants under non-uniform salinity extruded more Na(+) from the root than those under uniform salinity. Root Na(+) efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na(+) efflux and H(+) influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na(+) extrusion was probably due to active Na(+)/H(+) antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na(+) concentration, transport of excessive foliar Na(+) to the low salinity side, and enhanced Na(+) efflux from the low salinity root.

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