Background and aims Efficient accumulation of arsenic (As) in rice (Oryza sativa L.) poses a potential health risk to rice consumers. The aim of this study was to investigate the mechanisms of the uptake, transport and distribution of inorganic arsenic (Asi) and dimethylarsinic acid (DMA).
Methods Rice was exposed to Asi and DMA under hydroponics. High-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and synchrotron X-ray fluorescence (SXRF) microprobe were used to determine As concentration and in situ map As distribution.
Results DMA induced abnormal florets before flowering and caused a sharp decline in seed setting rate after flowering compared to Asi. Rice grains accumulated 2-fold higher DMA than Asi. The distribution of Asi concentration (root > leaf > husk > caryopsis) in As(V) treatments was different from that of the DMA concentration (caryopsis> husk> root ≥leaf) in DMA treatments. The SXRF observed that Asi mainly accumulated in vascular trace and less in endosperm, while DMA was observed in both tissues.
Conclusions DMA tended to accumulate in caryopsis, induced higher toxicity to reproductive tissues and then markedly reduced the rice yield, while Asi mainly remained in vegetative tissues and had no significant effect on the yield. DMA is more toxic than Asi to reproductive tissues.