Phytotoxicity and detoxification mechanism differ among inorganic and methylated arsenic species in Arabidopsis thaliana
Phytotoxicity and detoxification mechanism differ among inorganic and methylated arsenic species in Arabidopsis thaliana
复制标题
拟南芥中无机砷和甲基化砷的植物毒性和解毒机制不同
DOI：
10.1007/s11104-015-2739-3
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发表时间：
2016
期刊：
影响因子：
4.9
通讯作者：
Zhao Fang-Jie
中科院分区：
文献类型：
--
作者：
Tang Zhong;Kang Yuanyuan;Wang Peitong;Zhao Fang-Jie
背景与目的植物能吸收无机砷和甲基化砷，但不同砷种的植物毒性模式和解毒机制是否不同尚不清楚。本研究旨在探讨砷（As（V））、甲基胂酸（MMA（V））和二甲基胂酸（DMA（V））对拟南芥的毒性差异及其解毒机制。比较了As（V）、MMA（V）和DMA（V）处理下野生型植物的根冠生长、种子产量、As积累和氧化胁迫指标。利用谷胱甘肽（GSH）生物合成的特异性抑制剂和GSH合成缺陷突变体（cad 2 -1）、植物螯合素（PC）合成缺陷突变体（cad 1 -3）和As（III）-PC液泡膜转运蛋白（abcc 1 -2）研究了巯基在砷解毒中的作用。thaliana.甲基化As比As（V）更有效地从根向地上部和地上部向种子转移。DMA（V）暴露导致更大的氧化应激比其他物种。As（V）和MMA（V）诱导非蛋白硫醇（NPT）的产生，而DMA（V）不诱导。GSH抑制剂BSO显著提高了细胞对As（V）和MMA（V）的敏感性，但降低了对DMA（V）的敏感性。突变体cad 1 -3、cad 2 -1和abcc 1 -2对As（V）和MMA（V）同样敏感，但对DMA（V）不敏感。As（V）和MMA（V）对硫同化基因ATP硫酸化酶（ATPS）和腺苷5′磷酸硫酸还原酶（APR 1）的表达的促进作用大于DMA（V）。thaliana比As（V）或MMA（V）更强。MMA（V）的解毒机制与As（V）相似，包括巯基生成、与PC络合和空泡隔离。这种机制对DMA（V）的解毒是无效的。
Background and aimsPlants are able to take up inorganic arsenic (As) and methylated As, but whether the mode of phytotoxicity and the detoxification mechanism differ between different As species remains unclear. This study aimed to investigate the differences in phytotoxicity and detoxification mechanism between arsenate [As(V)], monomethylarsonic acid [MMA(V)] and dimethylarsinic acid [DMA(V)].MethodsArabidopsis thaliana was grown in agar-solidified medium, hydroponic or soil pot experiments. Root and shoot growth, seed production, As accumulation and oxidative stress indicators of wild-type plants exposed to As(V), MMA(V) and DMA(V) were compared. The role of thiols in As detoxification was investigated using a specific inhibitor of glutathione (GSH) biosynthesis and the mutants defective in GSH synthesis (cad2-1), phytochelatin (PC) synthesis (cad1-3) or tonoplast transporters for As(III)-PCs (abcc1-2).ResultsMethylated As species, especially DMA(V), were more toxic than As(V) for growth and seed production in A. thaliana. Methylated As species were more efficiently translocated from roots to shoots and from shoots to seeds than As(V). DMA(V) exposure resulted in a greater oxidative stress than other As species. As(V) and MMA(V) induced the production of non-protein thiols (NPT), but DMA(V) did not. The GSH inhibitor BSO greatly enhanced the sensitivity to As(V) and MMA(V), but decreased the sensitivity to DMA(V). The mutants cad1-3, cad2-1 and abcc1-2 were similarly hypersensitive to As(V) and MMA(V), but not to DMA(V). As(V) and MMA(V) enhanced the expression of the sulphur assimilation genes encoding ATP Sulphurylase (ATPS) and adenosine-5′-phosphosulphate reductase (APR1) more than DMA(V).ConclusionsDMA(V) is more toxic to A. thaliana than As(V) or MMA(V). The detoxification mechanism for MMA(V) is similar to that for As(V), involving thiol production, complexation with PCs and vacuolar sequestration. This mechanism is ineffective for the detoxification of DMA(V).