Department of Plant and Soil Sciences, University of Delaware, Newark, DE, 19716, USA.
Sci Rep. 2022 Mar 25;12(1):5210. doi: 10.1038/s41598-022-09236-3.
Previous work has shown that inorganic As localizes in rice bran whereas DMA localizes in the endosperm, but less is known about co-localization of As and S species and how they are affected by growing conditions. We used high-resolution synchrotron X-ray fluorescence imaging to image As and S species in rice grain from plants grown to maturity in soil (field and pot) and hydroponically (DMA or arsenite dosed) at field-relevant As concentrations. In hydroponics, arsenite was localized in the ovular vascular trace (OVT) and the bran while DMA permeated the endosperm and was absent from the OVT in all grains analyzed, and As species had no affect on S species. In pot studies, soil amended with Si-rich rice husk with higher DMA shifted grain As into the endosperm for both japonica and indica ecotypes. In field-grown rice from low-As soil, As localized in the OVT as arsenite glutathione, arsenite, and DMA. Results support a circumferential model of grain filling for arsenite and DMA and show Si-rich soil amendments alter grain As localization, potentially lessening risk to rice consumers.
先前的研究表明，无机砷在米糠中积累，而 DMA 则在胚乳中积累，但对于砷和硫的同定位以及它们如何受到生长条件的影响知之甚少。我们使用高分辨率同步加速器 X 射线荧光成像技术，对在土壤（田间和盆栽）和水培（DMA 或亚砷酸盐剂量）中成熟生长的水稻籽粒中的砷和硫进行了成像，这些生长条件下的砷浓度与田间实际情况相关。在水培中，亚砷酸盐定位于珠心维管束（OVT）和糠皮中，而 DMA 则渗透到胚乳中，在所有分析的籽粒中都不存在于 OVT 中，且砷形态对硫形态没有影响。在盆栽研究中，用富含硅的稻壳改良的土壤，使 DMA 含量增加，从而使粳稻和籼稻的籽粒中的砷进入胚乳。在低砷土壤中生长的田间水稻中，砷以谷胱甘肽亚砷酸盐、亚砷酸盐和 DMA 的形式定位于 OVT 中。研究结果支持了砷和 DMA 的环状填充模式，并表明富含硅的土壤改良剂改变了谷物中砷的定位，可能降低了对水稻消费者的风险。
