Arsenate, arsenite and dimethyl arsinic acid (DMA) uptake and tolerance in maize (Zea mays L.)
- 468 Downloads
The influx of arsenate, arsenite and dimethyl arsinic acid (DMA) were studied in 7-day-old excised maize roots (Zea mays L.), and then related to arsenate, arsenite and DMA toxicity. Arsenate, arsenite and DMA influx was all found concentration dependent with significant genotypic differences for arsenite and DMA. Arsenate influx in phosphate starved plants best fitted the four-parameter Michaelis–Menten model corresponding to an additive high and low affinity uptake system, while the uptake of phosphate replete plants followed the two parameter model of Michaelis–Menten kinetics. Arsenite influx was well described by the two parameter model of ‘Michaelis–Menten’ kinetics. DMA influx was comprised of linear phase and a hyperbolic phase. DMA influx was much lower than that for arsenite and arsenate. Arsenate and DMA influx decreased when phosphate was given as a pre-treatment as opposed to phosphate starved plants. The +P treatment tended to decrease influx by 50% for arsenate while this figure was 90% for DMA. Arsenite influx increasing slightly at higher arsenite concentrations in P starved plants but at lower arsenite concentrations, there was little or no difference in arsenite uptake. Low toxicity was found for DMA on maize compared with arsenate and arsenite and the relative toxicity of arsenic species was As(V) > As(III) >> DMA.
KeywordsArsenic species Influx kinetics Maize Tolerance
- Hood RD (1985) Cacodylic acid: agricultural uses, biologic effects, and environmental fate. V. A. Monograph. 171 pp Avail. from Sup Documents, US Government Printing Office, Washington, DC, 20402Google Scholar
- US Environmental Protection Agency EPA (2005) Mode of carcinogenic action for cacodylic acid (dimethylarsinic acid, DMAV) and recommendations for dose response extrapolation. Available at: http://www.epa.gov/oppsrrd1/reregistration/cacodylic_acid/dma_moa.pdf
- US Environmental Protection Agency EPA (2006) Reregistration eligibility decision for MSMA, DSMA, CAMA, and cacodylic ccid. Available at: http://www.epa.gov/pesticides/reregistration/REDs/organic_arsenicals_red.pdf
- Zaman K, Pardini RS (1996) An overview of the relationship between oxidative stress and mercury and arsenic. Toxic Subst Mech 15:151–181Google Scholar