College of Life Sciences, South China Agricultural University, Guangzhou 510642, People's Republic of China.
Department of Environmental Sciences, Rutgers University, New Brunswick, NJ 08901, USA.
Sci Total Environ. 2019 May 20;666:445-460. doi: 10.1016/j.scitotenv.2019.02.281. Epub 2019 Feb 18.
Cadmium (Cd) and arsenic (As) are nonessential and toxic elements in rice that often occur together in contaminated paddy field soils. To understand whether rice has a common molecular response mechanism against Cd and As toxicity, 30-day seedlings (Oryza sativa L. indica) were exposed separately to Cd and As in hydroponic cultures for up to 7 days. Root transcriptomic analysis of plants exposed to Cd and As for 3 days revealed that a total of 2224 genes in rice roots responded to Cd stress, while 1503 genes responded to As stress. Of these, 841 genes responded to both stressors. The genes in common to Cd and As stress were associated with redox control, stress response, transcriptional regulation, transmembrane transport, signal transduction, as well as biosynthesis and metabolism of macromolecules and sulfur compounds. In plants exposed to Cd and As separately or in combination for 3 and 7 days, qRT-PCR verification revealed that the glutathione metabolism associated gene Os09g0367700 was significantly up-regulated with respect to unexposed controls and had a positive synergistic effect under combined Cd and As stress. In addition, the redox control related genes Os06g0216000, Os07g0638300 and Os01g0294500, the glutathione metabolism related gene Os01g0530900, the cell wall biogenesis related genes Os05g0247800, Os11g0592000 and Os03g0416200, the expression regulation related genes Os07g0597200 and Os02g0168200, and the transmembrane transport related genes Os04g0524500, also varied significantly with respect to an unexposed control and displayed synergistic effects after 7 days of simultaneous exposure to Cd and As. Our identification of a novel set of genes in rice which responded to both Cd and As stress may be of value in mitigating the toxicity of co-contaminated soils. These results also provide a deeper understanding of the molecular mechanisms involved in response to multi-metal/loids stress, and may be used in the genetic improvement of rice varieties.
镉（Cd）和砷（As）是水稻中两种非必需的有毒元素，它们经常在受污染的稻田土壤中共同存在。为了了解水稻是否对 Cd 和 As 的毒性有共同的分子响应机制，我们将 30 天的水稻幼苗（Oryza sativa L. indica）分别暴露在水培培养物中，接受 Cd 和 As 的处理，时间长达 7 天。暴露于 Cd 和 As 3 天的植物根系转录组分析表明，水稻根系中共有 2224 个基因对 Cd 胁迫有反应，而 1503 个基因对 As 胁迫有反应。其中，841 个基因对这两种胁迫都有反应。对 Cd 和 As 胁迫有共同反应的基因与氧化还原控制、应激反应、转录调控、跨膜转运、信号转导以及生物大分子和硫化合物的生物合成和代谢有关。在分别或同时暴露于 Cd 和 As 3 天和 7 天的植物中，qRT-PCR 验证显示，与未暴露对照相比，与谷胱甘肽代谢相关的基因 Os09g0367700 显著上调，并在 Cd 和 As 联合胁迫下具有正协同作用。此外，氧化还原控制相关基因 Os06g0216000、Os07g0638300 和 Os01g0294500、谷胱甘肽代谢相关基因 Os01g0530900、细胞壁生物合成相关基因 Os05g0247800、Os11g0592000 和 Os03g0416200、表达调控相关基因 Os07g0597200 和 Os02g0168200、以及跨膜转运相关基因 Os04g0524500，与未暴露对照相比也有显著差异，并在同时暴露于 Cd 和 As 7 天后表现出协同作用。我们在水稻中鉴定出了一组对 Cd 和 As 胁迫均有反应的新基因，这可能有助于减轻受污染土壤的毒性。这些结果还为深入了解多金属/类金属胁迫下的分子机制提供了依据，并可用于水稻品种的遗传改良。
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