Calcium regulates K⁺/Na⁺ homeostasis in rice (Oryza sativa L.) under saline conditions

Abstract

To investigate the effects of Ca 2+ on cation accumulation and K + /Na + selectivity, in this study, two-week-old rice (Oryza sativa L.) plants were exposed to 25 or 125 mmol/L NaCl with or without 10 mmol/L CaCl 2 . At low salinity (25 mmol/L NaCl), Ca 2+ significantly decreased Na + accumulation in roots, increased K + accumulation in shoots, and maintained higher K + /Na + ratios in both roots and shoots of rice plants. At high salinity (125 mmol/L NaCl), however, Ca 2+ did not have any effects on Na + , K + accumulation and K + /Na + ratios in plants. Further analysis showed that, at low salinity, the addition of Ca 2+ significantly enhanced the selective absorption and transport capacity for K + over Na + in rice. Although Na + efflux and Na + influx were remarkably reduced by Ca 2+ under both low and high salt stresses, their ratio was lowered only under low salt stress. In summary, these results suggest that Ca 2+ could regulate K + /Na + homeostasis in rice at low salinity by enhancing the selectivity for K + over Na + , reducing the Na + influx and efflux, and lowering the futile cycling of Na + .

Manganese-induced salt stress tolerance in rice seedlings: regulation of ion homeostasis, antioxidant defense and glyoxalase systems

“…Decreased Mn was also observed under the salt-stress condition due to disrupted ion homeostasis. A similar salt-induced ion imbalance was reported in previous studies (Tuncturk et al 2008;Wu and Wang 2012). However, in our study, Mn supplementation decreased Na ?…”

“…efflux and triggers K ? leakage from plant cells (Cramer et al 1985;Shabala et al 2006;Wu and Wang 2012;Rahman et al 2016a). Higher Na ?…”

“…Enhancing ionic and osmotic homeostasis plus detoxifying ROS and MG are some salt-stress tolerance responses in plants (Wu and Wang 2012;Wutipraditkul et al 2015;Rahman et al 2016a, b). Usually, plants produce proline (Pro) or other compatible solutes to stabilize osmotic homeostasis by maintaining the water relationship and stabilizing protein and enzyme complexes (Iqbal et al 2015;Reddy et al 2015;Nahar et al 2016a).…”

“…influx by applying exogenous phytoprotectants are important strategies to reduce salt-induced damage in plants (Hasanuzzaman et al 2011a;Wu and Wang 2012;Nahar et al 2015;Ozfidan-Konakci et al 2015).…”

Remediation of salt and boron-affected soil by addition of organic matter: an investigation into improving tomato plant productivity

“…This may be associated with the enhancement of biological activity in the crop rhizosphere by some physiologically active substance in the OM. Wu and Wang (2012) reported that OM also decreased the sodium absorption ratio (SAR), indicating the migration of exchangeable Na + from the top soil layer and accumulation in lower depths with application of OM. The K + and Ca 2+ concentrations in leaf were maintained or increased under OM treatments (Table 3).…”