bpl-200904-0031 ArticleInAPeriodical 2009 Biologia plantarum 53 4 https://bp.ueb.cas.cz/artkey/bpl-200904-0031.php https://doi.org/10.1007/s10535-009-0140-x 764-768 VoigtE. L. CaitanoR. F. MaiaJ. M. Ferreira-SilvaS. L. De MacêdoC. E. C. SilveiraJ. A. G. Involvement of cation channels and NH₄⁺-sensitive K⁺ transporters in Na⁺ uptake by cowpea roots under salinity Na⁺ accumulation was investigated in the roots of 11-d-old cowpea [Vigna unguiculata (L.) Walp.] plants. The relative contribution of different membrane transporters on Na⁺ uptake was estimated by applying Ca²⁺, K⁺, NH₄ ⁺, and pharmacological inhibitors. Na⁺ accumulation into the root symplast was decreased by half in the presence of 1 mM Ca²⁺ and it was almost abolished by 100 mM K⁺. The inhibitory effect of external NH⁴⁺ on Na⁺ accumulation was more pronounced in the roots of NH₄ ⁺-free growing plants. Na⁺ accumulation was reduced about 73 % by 0.1 mM flufenamate and it was almost blocked by 2 mM quinine. In addition, 20 mM tetraethylammonium and 1.0 mM Cs⁺ decreased Na⁺ accumulation by 28 and 30 %, respectively. These results evidenced that low-affinity Na⁺ uptake by cowpea roots depends on Ca²⁺-sensitive and Ca²⁺-insensitive pathways. The Ca²⁺-sensitive pathway is probably mediated by nonselective cation channels and the Ca²⁺-insensitive one may involve K⁺ channels and to a lesser extent NH₄ ⁺-sensitive K⁺ transporters.