Glyphosate, the most commonly used herbicide in the world, controls a wide range of plant species, mainly because plants have little capacity to metabolize (detoxify) glyphosate. Massive glyphosate use has led to world-wide evolution of glyphosate-resistant (GR) weed species, including the economically damaging grass weed Echinochloa colona An Australian population of E colona has evolved resistance to glyphosate with unknown mechanisms that do not involve the glyphosate target enzyme 5-enolpyruvylshikimate-3-P synthase. GR and glyphosate-susceptible (S) lines were isolated from this population and used for resistance gene discovery. RNA sequencing analysis and phenotype/genotype validation experiments revealed that one aldo-keto reductase (AKR) contig had higher expression and higher resultant AKR activity in GR than S plants. Two full-length AKR (EcAKR4-1 and EcAKR4-2) complementary DNA transcripts were cloned with identical sequences between the GR and S plants but were upregulated in the GR plants. Rice (Oryza sativa) calli and seedlings overexpressing EcAKR4-1 and displaying increased AKR activity were resistant to glyphosate. EcAKR4-1 expressed in Escherichia coli can metabolize glyphosate to produce aminomethylphosphonic acid and glyoxylate. Consistent with these results, GR E colona plants exhibited enhanced capacity for detoxifying glyphosate into aminomethylphosphonic acid and glyoxylate. Structural modeling predicted that glyphosate binds to EcAKR4-1 for oxidation, and metabolomics analysis of EcAKR4-1 transgenic rice seedlings revealed possible redox pathways involved in glyphosate metabolism. Our study provides direct experimental evidence of the evolution of a plant AKR that metabolizes glyphosate and thereby confers glyphosate resistance.

中文翻译：

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醛酮还原酶代谢草甘膦并赋予稗草抗草甘膦性。


草甘膦是世界上最常用的除草剂，控制着多种植物物种，主要是因为植物代谢（解毒）草甘膦的能力很小。草甘膦的大量使用导致世界范围内抗草甘膦 (GR) 杂草物种的进化，包括具有经济破坏性的禾本科杂草稗 澳大利亚的稗草种群已经进化出对草甘膦的抗性，其机制未知，但不涉及草甘膦目标酶5-烯醇丙酮酰莽草酸-3-P合酶。从该群体中分离出 GR 和草甘膦敏感 (S) 系，并用于发现抗性基因。 RNA 测序分析和表型/基因型验证实验表明，一种醛酮还原酶 (AKR) 重叠群在 GR 中比 S 植物具有更高的表达和更高的 AKR 活性。两个全长 AKR（EcAKR4-1 和 EcAKR4-2）互补 DNA 转录物在 GR 和 S 植物之间克隆，具有相同的序列，但在 GR 植物中上调。过度表达 EcAKR4-1 并表现出增加的 AKR 活性的水稻 (Oryza sativa) 愈伤组织和幼苗对草甘膦具有抗性。大肠杆菌中表达的EcAKR4-1可以代谢草甘膦产生氨甲基膦酸和乙醛酸盐。与这些结果一致，GR E 结肠植物表现出增强的将草甘膦解毒成氨甲基膦酸和乙醛酸盐的能力。结构模型预测草甘膦与 EcAKR4-1 结合进行氧化，EcAKR4-1 转基因水稻幼苗的代谢组学分析揭示了草甘膦代谢中可能涉及的氧化还原途径。我们的研究提供了植物 AKR 进化的直接实验证据，AKR 代谢草甘膦，从而赋予草甘膦抗性。