Background

World agricultural production of genetically modified (GM) products, in particular, the combination of different traits/genes in the same plant has been a trend over the last decade. There have been concerns raised over stacking multiple herbicide and insect-resistant transgenes that could result in fitness costs depending on the type and strength of selection pressures exerted by the environment. Here, we report the results of transcriptomic analysis comparing the effect of glyphosate-based herbicide (GBH) in the single-transgene versus stacked, herbicide-resistant soybean varieties on various biological processes, metabolic pathways, and key shikimic enzymes.

Results

Gene expression data showed that defense metabolism and redox homeostasis were equally modulated in single-transgene and stacked-variety samples. Carbon accumulation and energy metabolisms were distinct between the varieties and photosynthesis metabolism was found negatively affected in the single-transgene variety only. In the stacked variety, the shikimate pathway was modulated by the accumulation of transcripts from phenylalanine gene and other cascade genes. As expected, the expression of native EPSPS was upregulated in both varieties when herbicide was applied. On the other hand, transgenic EPSPS expression was down-regulated in both GM varieties upon herbicide application which cannot be explained.

Conclusion

Glyphosate-based herbicides toxicity suggests its effects on carbon central metabolism and flux, redox metabolism, photosynthesis, and to hormone and defense response in plants. The observed unintended effects in GM herbicide-tolerant varieties unravel the deleterious effects previously observed on GM-tolerant varieties growth and production. The impact of GBH on shikimate and cascade pathways was observed in terms of both native and transgenic insensitive EPSPS modulation, alteration of jasmonic acid and lignin metabolism in both single-transgene and stacked variety. The energy metabolism and carbon flux were differently affected in these varieties. Oxidative stress, more specifically glutathione metabolism, induced by GBH, was also observed in this study. The stacked variety showed a more pronounced stress response (activation of specific stress defense proteins, Rboh, WRKY) and secondary compounds (β-glucosidase, isoflavone 7-O-methyltransferase). Omics profiling techniques, such as transcriptomics, can be considered tools to support risk assessment in detecting unintended effects due to the GBH application.

中文翻译：

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堆叠的转基因大豆具有除草剂抗性，而杀虫剂rCry1Ac在使用草甘膦类除草剂后显示出强大的防御能力和氧化还原稳态障碍

背景

过去十年来，世界农业生产转基因（GM）产品，尤其是同一植物中不同性状/基因的组合一直是趋势。堆叠多种除草剂和抗虫转基因可能引起关注，这取决于环境施加的选择压力的类型和强度，可能导致健身成本增加。在这里，我们报告了转录组学分析的结果，比较了单转基因草甘膦型除草剂（GBH）与堆叠的抗除草剂大豆品种在各种生物过程，代谢途径和关键key草酶上的作用。

结果

基因表达数据显示，在单转基因和堆叠品种样品中，防御代谢和氧化还原稳态被均等地调节。碳的积累和能量代谢在不同的品种之间是不同的，而光合作用的代谢仅对单转基因品种有负面影响。在堆积的品种中，the草酸途径是由苯丙氨酸基因和其他级联基因的转录物的积累调节的。如所预期的，当施用除草剂时，天然EPSPS的表达在两个品种中均被上调。另一方面，两种除草剂施用后的转基因EPSPS表达下调，这无法解释。

结论

基于草甘膦的除草剂毒性表明其对碳中枢代谢和通量，氧化还原代谢，光合作用以及对植物激素和防御反应的影响。在耐转基因除草剂品种中观察到的意外影响揭示了先前观察到的耐转基因品种生长和生产的有害影响。从天然和转基因不敏感的EPSPS调节，茉莉酸的改变以及单转基因和堆叠品种中的木质素代谢方面，均观察到GBH对iki草酸酯和级联途径的影响。在这些品种中，能量代谢和碳通量受到不同的影响。在这项研究中还观察到了由GBH引起的氧化应激，尤其是谷胱甘肽代谢。O-甲基转移酶）。诸如转录组学的组学分析技术可以被认为是支持风险评估的工具，可用于检测由于应用GBH引起的意外影响。