Effects of salt stress on ion balance and nitrogen metabolism in rice

Abstract

The aim of this study was to test the effects of salt stress on nitrogen metabolism and ion balance in rice plants. The contents of inorganic ions, total amino acids, and NO 3 -in the stressed seedlings were then measured. The expressions of some critical genes involved in nitrogen metabolism were also assayed to test their roles in the regulation of nitrogen metabolism during adaptation of rice to salt stress. The results showed that when seedlings were subjected to salt stress for 4 h, in roots, salt stress strongly stimulated the accumulations of Na + and Cl -, and reduced K + content; however, in leaves, only at 5 days these changes were observed. This confirmed that the response of root to salt stress was more sensitive than that of leaf. When seedlings were subjected to salt stress for 4 h, salt stress strongly stimulated the expression of OsGS1;1, OsNADH-GOGAT, OsAS, OsGS1;3, OsGDH1, OsGDH2, OsGDH3 in both leaves and roots of rice, after this time point their expression decreased. Namely, at 5 days most of genes involved in NH 4 + assimilation were downregulated by salt stress, which might be the response to NO 3 -change. Salt stress did not reduce NO 3 -contents in both roots and leaves at 4 h, whereas at 5 days salt stress mightily decreased the NO 3 -contents. The deficiencies of NO 3 -in both roots and leaves can cause a large downregulation of OsNR1 and the subsequent reduction of NH 4 + production. This event might immediately induce the downregulations of the genes involved in NH 4 + assimilation.

Effect of Humic Acid Application on Growth and Chlorophyll Contents of Common Bean Plants (Phaseolus vulgarisL.)Under Salinity Stress Conditions

“…Under saline conditions, plants are stressed in three ways; (1) water deficit due to reduced water potential in the root zone, (2) nutrient imbalance by depression in uptake and/or shoot transport (3) phytotoxicity of ions such as Na + and Cl - [8;9 and10]. This is attributed to the fact that Na + competes with K + for binding sites for cellular function [11].…”

Effects of NaCl stress on accumulation of K+, Na+, Cl-, NO3 -,sugar and proline contents in the seedlings of Triticale-I

“…Similar stimulation of Na + accumulation in the root and the shoot of Triticale was observed at 14-and 21-day of treatment following 50 -150 mM NaCl treatment (Figs 2a,b and 3a,b). Salinity was also found to increase the accumulation of Na + in rice (Wang et al 2012). K + accumulation in the root and the shoot was decreased by 93, 85 and 71% at 50, 100 and 150 mM NaCl treatment respectively at 7-day of treatment (Fig.…”

“…4b,c). On the contrary, salinity was found to increase Cl -accumulation in rice (Wang et al 2012). In Triticale, a decrease in uptake of chloride indicates that chloride exclusion pump might exist in plasmamembrane.…”

“…Salt stress undesirably affects plant growth and productivity during all developmental stages (Abari et al 2011). Na + and Cl -content in both shoots and roots increased with the increase in salinity in a wide range of plant species (Wang et al 2012 andMajid et al 2012). Salinity stress had an inhibitory effect on accumulation of K + in barley and rice (Tavakkoli et al 2011 andAlamgir et al 2007).…”

“…Salt stress decreased NO 3 -content in rice (Wang et al 2012) and Achillea fragratissima Forssk (Abd El-Azim and Ahmed 2009). Salinity induced a significant increase in proline concentration in rice and purslane (Rao et al 2013 andRahdari et al 2012).…”