Methylated arsenic species in rice: geographical variation, origin, and uptake mechanisms.
Methylated arsenic species in rice: geographical variation, origin, and uptake mechanisms.
复制标题
DOI：
10.1021/es304295n
复制
发表时间：
2013-04
影响因子：
11.4
通讯作者：
F. Zhao;Yong-guan Zhu;A. Meharg
中科院分区：
文献类型：
--
作者：
F. Zhao;Yong-guan Zhu;A. Meharg
水稻是人类饮食中无机砷（iAs）的主要来源，因为水稻能有效地积累砷。水稻As的形成主要由iAs和二甲基硅酸（DMA）主导。本文综述了水稻物种形成的全球格局及其变化的原因。亚洲产水稻的砷含量与总砷含量呈明显的线性关系，斜率为0.78。在欧洲和美国生产的水稻显示出更多的变化，但通常是双曲线关系，DMA在美国水稻中占主导地位。虽然稻谷物种形成存在显著的基因型差异，但区域差异主要归因于环境因素。新的证据还表明，水稻中甲基化的As来源于土壤，而水稻缺乏As甲基化能力。土壤淹水和有机质的添加增加了As的微生物甲基化，尽管对甲基化负责的微生物群落知之甚少。与iAs相比，甲基化的iAs被水稻根系吸收的效率较低，但转运到籽粒的效率要高得多，这可能是水稻颖花不育症（直穗病）的一个重要原因。DMA是一种弱致癌物，但从大米中摄入的水平远低于人们关注的水平。确定了需要进一步调查的问题。
Rice is a major source of inorganic arsenic (iAs) in the human diet because paddy rice is efficient at accumulating As. Rice As speciation is dominated by iAs and dimethylarsinic acid (DMA). Here we review the global pattern in rice As speciation and the factors causing the variation. Rice produced in Asia shows a strong linear relationship between iAs and total As concentration with a slope of 0.78. Rice produced in Europe and the United States shows a more variable, but generally hyperbolic relationship with DMA being predominant in U.S. rice. Although there is significant genotypic variation in grain As speciation, the regional variations are primarily attributed to environmental factors. Emerging evidence also indicates that methylated As species in rice are derived from the soil, while rice plants lack the As methylation ability. Soil flooding and additions of organic matter increase microbial methylation of As, although the microbial community responsible for methylation is poorly understood. Compared with iAs, methylated As species are taken up by rice roots less efficiently but are transported to the grain much more efficiently, which may be an important factor responsible for the spikelet sterility disorder (straight-head disease) in rice. DMA is a weak carcinogen, but the level of ingestion from rice consumption is much lower than that of concern. Questions that require further investigations are identified.