Phytotoxicity and uptake of roxarsone by wheat (Triticum aestivum L.) seedlings.
Roxarsone (ROX), the primary aromatic arsenical additive (AAA) used in animal feeding operations, is of increasing concern to environmental and human health due to land application of ROX-laden animal manure. Few studies have investigated the phytotoxicity, uptake mechanisms, and speciation of AAA in crop plants. In this study, wheat seedlings were employed to address these issues under hydroponic conditions. Compared to inorganic arsenic, ROX was less toxic to wheat root elongation. Wheat roots were more sensitive to ROX stress than shoots. For the first time, metabolized inorganic arsenic was detected in plants, although ROX was the predominant detected arsenic species in wheat seedlings. ROX uptake and toxicity to roots were inhibited by humic acid at concentrations higher than 50 mg/L due to interaction with ROX. Phosphate enhanced ROX uptake, but no trends were observed for ROX uptake in the presence of glycerol at concentrations lower than 250 mM. In addition, ROX uptake was significantly decreased by silicate (Si(IV), 0.5-10 mM) and the metabolic inhibitor, 2,4-dinitrophenol (0.5-2 mM), indicating that ROX transport into wheat roots was actively mediated by Si(IV)-sensitive transporters. These findings provide important insights into the fate and speciation of AAA in soil-water-plant systems relevant to human health.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
Qing-Long
QL
Fu
Department of Chemical, Biochemical and Environmental Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA.
Lee
L
Blaney
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: dmzhou@issas.ac.cn.
Dong-Mei
DM
Zhou
D019297:2,4-Dinitrophenol / Q000494:pharmacology; D001151:Arsenic / Q000032:analysis / Q000378:metabolism / Q000633:toxicity; D001152:Arsenicals / Q000378:metabolism*; D001693:Biological Transport, Active; D004787:Environmental Pollution / Q000009:adverse effects; D005990:Glycerol / Q000494:pharmacology; D018527:Hydroponics; D010710:Phosphates / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D012406:Roxarsone / Q000032:analysis / Q000378:metabolism* / Q000633:toxicity*; D036226:Seedlings / Q000187:drug effects* / Q000378:metabolism*; D017640:Silicates / Q000494:pharmacology; D014908:Triticum / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
D001152:Arsenicals; D010710:Phosphates; D017640:Silicates; D012406:Roxarsone; D001151:Arsenic; D005990:Glycerol; D019297:2,4-Dinitrophenol
Arsenic; Organoarsenicals; Phytotoxicity; Uptake mechanism; Wheat