THE EFFECTS OF PHOSPHATE ON ARSENIC UPTAKE AND TOXICITY ALLEVIATION IN TOBACCO GENOTYPES WITH DIFFERING ARSENIC TOLERANCES

Phosphate (PO43-) has been reported to suppress arsenate (As-v) uptake in plants. However, its effects on controlling the availability of As-v in tobacco genotypes with different arsenic (As) tolerances has not been fully explored. In the present study, the effects of PO43- on As-v uptake were investigated in a hydroponic culture using 2 tobacco (Nicotiana tabacum) genotypes (ZY90 and FSMY) that differed in As-v tolerance. A total of 9 treatment combinations comprising As-v treatments of 0 mu M, 10 mu M, and 100 mu M and PO43- treatments of 0 mu M, 50 mu M, and 500 mu M were used. The results showed that ZY90 had greater reductions in leaf photosynthetic parameters, root and shoot dry weight, length, and nutrient content than did FSMY when exposed to As-v stress. The addition of 500 mu M external PO43- significantly suppressed As-v (100 mu M) uptake in both FSMY and ZY90, with the effect being more pronounced in FSMY. Greater PO43- uptake in plants significantly reduced the influx of As-v, causing an increase in photosynthesis and nutrient uptake. Phosphate supply increased superoxide dismutase activity, catalase activity, and malondialdehyde content. The present study showed that PO43- is an effective competitive inhibitor of As-v, and it can be effectively used to control As-v accumulation in tobacco plants. Environ Toxicol Chem 2015;34:45-52. (c) 2014 SETAC