Effects of ammonium nitrate, cesium chloride and tetraethylammonium on high-affinity potassium uptake in habanero pepper plantlets (Capsicum chinense Jacq.)

Abstract

Potassium (K + ) is an essential nutrient and the most abundant cation in plant cells. Plants have a wide variety of transport systems for K + acquisition that catalyze K + uptake across a wide spectrum of external K + concentrations and mediate K + movement within the plant, as well as its release into the environment. The KUP/HAK/KT transporter family plays a key role in K + homeostasis in plant cells. The present study demonstrates that habanero pepper plantlets have a clear pattern of K + uptake when resupplemented with K + after K + starvation. Habanero pepper plantlets, re-supplemented with a solution containing low concentrations of K + after 72, 96 or 120 h of K + starvation were able to decrease the amount of K + in the solution at different time points. To study the effect of NH 4 + , we added different concentrations of NH 4 NO 3 to the medium solution and demonstrated that NH 4 + inhibited K + uptake in a dose-dependent manner. When the plantlets were subjected to K + starvation for 72 h and then resupplemented with 50 or 100 μM K + , exposure to K + channel blockers (10 mM CsCl and 20 mM TEA) decreased their K + uptake compared with the control treatment. A model demonstrating the process of K + uptake through an NH 4 + -insensitive component was proposed. Key words : Potassium, high affinity transporters, channel blockers, ammonium.