High-affinity K+ uptake in pepper plants

Abstract

High-affinity K+ uptake is an essential process for plant nutrition under K+-limiting conditions. The results presented here demonstrate that pepper (Capsicum annuum) plants grown in the absence of and starved of K+ show an NH+4-sensitive high-affinity K+ uptake that allows plant roots to deplete external K+ to values below 1 µM. When plants are grown in the presence of NH+4 high-affinity K+ uptake is not inhibited by NH+4. Although NH+4-grown plants deplete external K+ below 1 µM in the absence of when 1 mM is present they do not deplete external K+ below 10 µM. A K+ transporter of the HAK family, CaHAK1, is very likely mediating the NH+4-sensitive component of the high-affinity K+ uptake in pepper roots. CaHAK1 is strongly induced in the roots that show the NH+4-sensitive high-affinity K+ uptake and its induction is reduced in K+-starved plants grown in the presence of . The NH+4-insensitive K+ uptake may be mediated by an AKT1-like K+ channel.