Toxicity and subcellular distribution of cadmium in wheat as affected by dissolved organic acids.
We aim to investigate the effects of humic acid (HA) and citric acid (CA) on the toxicity and subcellular distribution of Cd in wheat. Results show that the toxicity and uptake of Cd decreased with increasing HA. The EC50 values of Cd increased from 3.36 micromol/L to 4.96 and 7.33 micromol/L at 50 and 250 mg/L HA, respectively, but decreased to 1.39 micromol/L in the presence of CA based on free ion activity model (FIAM). HA decreased the relative subcellular distribution of Cd in the heat-denatured proteins (decreased from 54% to 33%) but increased Cd in the heat-stable proteins in root (from 25% to 50%) at 7.61 micromol/L {Cd2+} (free Cd activity), which resulted in decreasing Cd toxicity. However, CA increased Cd toxicity due to the increased internalization of Cd although the relative subcellular distributions of Cd exhibited a decrease in the heat-denatured proteins and increase in the granule fraction compared to the control at high-level Cd. The FIAM could not predict the toxicity of Cd in the presence of organic acids. Alternatively, the internal Cd accumulation and subcellular Cd concentration were better to describe the toxicity of Cd to wheat.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. ddli@issas.ac.cn
Dandan
D
Li
Dongmei
D
Zhou
D001681:Biological Assay; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity*; D002264:Carboxylic Acids / Q000378:metabolism*; D019343:Citric Acid / Q000494:pharmacology; D006812:Humic Substances; D018517:Plant Roots / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism; D012995:Solubility / Q000187:drug effects; D012996:Solutions; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D014908:Triticum / Q000187:drug effects* / Q000378:metabolism*
D002264:Carboxylic Acids; D006812:Humic Substances; D012996:Solutions; D002104:Cadmium; D019343:Citric Acid