TY - JOUR
T1 - Cesium toxicity in Arabidopsis
AU - Hampton, CR
AU - Bowen, HC
AU - Broadley, MR
AU - Hammond, JP
AU - Mead, A
AU - Payne, KA
AU - Pritchard, Jeremy
AU - White, PJ
PY - 2004/11/1
Y1 - 2004/11/1
N2 - Cesium (Cs) is chemically similar to potassium (K). However, although K is an essential element, Cs is toxic to plants. Two contrasting hypotheses to explain Cs toxicity have been proposed: (1) extracellular Cs+prevents K+ uptake and, thereby, induces K starvation; and (2) intracellular Cs+ interacts with vital K+-binding sites in proteins, either competitively or noncompetitively, impairing their activities. We tested these hypotheses with Arabidopsis (Arabidopsis thaliana). Increasing the Cs concentration in the agar ([Cs]agar) on which Arabidopsis were grown reduced shoot growth. Increasing the K concentration in the agar ([K]agar) increased the [Cs]agar at which Cs toxicity was observed. However, although increasing [Cs]agar reduced shoot K concentration ([K]shoot), the decrease in shoot growth appeared unrelated to [K]shoot per se. Furthermore, the changes in gene expression in Cs-intoxicated plants differed from those of K-starved plants, suggesting that Cs intoxication was not perceived genetically solely as K starvation. In addition to reducing [K]shoot, increasing [Cs]agar also increased shoot Cs concentration ([Cs]shoot), but shoot growth appeared unrelated to [Cs]shoot per se. The relationship between shoot growth and [Cs]shoot/[K]shoot suggested that, at a nontoxic [Cs]shoot, growth was determined by [K]shoot but that the growth of Cs-intoxicated plants was related to the [Cs]shoot/[K]shoot quotient. This is consistent with Cs intoxication resulting from competition between K+ and Cs+ for K+-binding sites on essential proteins.
AB - Cesium (Cs) is chemically similar to potassium (K). However, although K is an essential element, Cs is toxic to plants. Two contrasting hypotheses to explain Cs toxicity have been proposed: (1) extracellular Cs+prevents K+ uptake and, thereby, induces K starvation; and (2) intracellular Cs+ interacts with vital K+-binding sites in proteins, either competitively or noncompetitively, impairing their activities. We tested these hypotheses with Arabidopsis (Arabidopsis thaliana). Increasing the Cs concentration in the agar ([Cs]agar) on which Arabidopsis were grown reduced shoot growth. Increasing the K concentration in the agar ([K]agar) increased the [Cs]agar at which Cs toxicity was observed. However, although increasing [Cs]agar reduced shoot K concentration ([K]shoot), the decrease in shoot growth appeared unrelated to [K]shoot per se. Furthermore, the changes in gene expression in Cs-intoxicated plants differed from those of K-starved plants, suggesting that Cs intoxication was not perceived genetically solely as K starvation. In addition to reducing [K]shoot, increasing [Cs]agar also increased shoot Cs concentration ([Cs]shoot), but shoot growth appeared unrelated to [Cs]shoot per se. The relationship between shoot growth and [Cs]shoot/[K]shoot suggested that, at a nontoxic [Cs]shoot, growth was determined by [K]shoot but that the growth of Cs-intoxicated plants was related to the [Cs]shoot/[K]shoot quotient. This is consistent with Cs intoxication resulting from competition between K+ and Cs+ for K+-binding sites on essential proteins.
UR - http://www.scopus.com/inward/record.url?scp=16344370664&partnerID=8YFLogxK
U2 - 10.1104/pp.104.046672
DO - 10.1104/pp.104.046672
M3 - Article
C2 - 15489280
SN - 1532-2548
SN - 1532-2548
SN - 1532-2548
SN - 1532-2548
SN - 1532-2548
SN - 1532-2548
VL - 136
SP - 3824
EP - 3837
JO - Plant Physiology
JF - Plant Physiology
ER -