Rice (Oryza sativa L.) grown on arsenic-containing soil and water become a primary dietary source of arsenic and pose a significant health risk. Gene modification is an important and practical approach to reduce arsenic accumulation in rice grains. Here, we reported a WaarsM gene of soil fungus Westerdykella aurantiaca, expressed in rice able to convert toxic inorganic arsenicals to methylated arsenic species, therefore, reduce arsenic accumulation in rice grains. In response to arsenic treatment in hydroponics, WaarsM expressing transgenic lines showed a marked increase in arsenic resistance and reduced its accumulation compared to NT. Also, WaarsM expressing transgenic Line 1 evolved c.a. 157 ng and c.a. 43 ng volatile arsenicals (mg⁻¹ fresh weight) after 72 hours of exposure to 25 μM AsIII and 250 μM AsV, respectively. Transgenic line 1, grown in soil irrigated with arsenic-containing water accumulates about 50% and 52% lower arsenic than the NT in shoot and root, respectively; while arsenic concentration in polished seeds and husk of the transgenic line was reduced by 52% compared to NT. Thus, the present study demonstrates that the expression of WaarsM in rice induces arsenic methylation and volatilization, provides a potential strategy to reduce arsenic accumulation in rice grain.

中文翻译：

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一种新颖的真菌砷甲基转移酶WaarsM减少了转基因水稻植株中谷物砷的积累

在含砷的土壤和水中生长的水稻（Oryza sativa L.）成为砷的主要饮食来源，对健康构成重大威胁。基因修饰是减少水稻籽粒中砷积累的重要且实用的方法。在这里，我们报道了土壤真菌Westerdykella aurantiaca的WaarsM基因，该基因在水稻中表达，能够将有毒的无机砷转化为甲基化砷，从而减少水稻籽粒中砷的积累。响应水培法中的砷处理，与NT相比，表达WaarsM的转基因品系显示出砷抗性的显着增加，并减少了其积累。此外，表达转基因品系1的WaarsM进化出大约暴露于25μMAsIII和250μMAsV 72小时后，分别产生157 ng和ca 43 ng挥发性砷（新鲜重量mg ^-1）。在用含砷水灌溉的土壤中生长的转基因品系1，在苗和根部的砷含量分别比NT低约50％和52％。而与NT相比，转基因品系的抛光种子和果壳中的砷浓度降低了52％。因此，本研究表明，WaarsM在水稻中的表达诱导砷甲基化和挥发，为减少水稻籽粒中砷的积累提供了潜在的策略。