Potassium silicate improves cellular sodium homeostasis in wheat (Triticum aestivum L.) cultivars differing in salt...

Salinity causes negative impacts on crops. We investigated the effect of potassium silicate (K₂SiO₃) on the cytosolic uptake of sodium, [Na⁺]_cyt, in mesophyll protoplasts of wheat cultivars differing in salt sensitivity. Protoplasts were isolated enzymatically from 1-week-old wheat seedlings of cvs. S-24 (salt tolerant) and Vinjett (salt sensitive). Protoplasts were loaded with the acetoxymethyl ester of SBFI, and subjected either to NaCl (0, 50, or 100 mM), followed by silicate (0 or 1 mM), or to silicate followed by NaCl. The sodium-fluorescence changes were quantified by epi-fluorescence microscopy. The cytosolic [Na⁺] uptake was higher in cv. Vinjett (salt-sensitive), than in cv. S24 (salt-resistant), which remained low even at high NaCl level. When silicate was added to protoplasts before NaCl, a significant reduction in [Na⁺]_cyt was observed for both cultivars compared with no silicate, but silicate addition after NaCl was less effective. Silicate treatment during the cultivation also reduced [Na⁺]_cyt uptake. Pharmacological results indicate that Na⁺ uptake in cv. Vinjett is mediated by both non-selective, NSCCs, and K-selective channels, but in cv. S-24 mainly by NSCCs. Silicate might inhibit Na⁺ influx by these channels. Our novel findings reveal that silicate reduces the cytosolic Na⁺ uptake in wheat mesophyll cells and that the silicate impact depends on the cultivars' exploited Na⁺ uptake proteins. Further investigation is needed to clarify the role of silicate on different Na⁺ uptake channels.