Gene amplification of 5-enol-pyruvylshikimate-3-phosphate synthase in glyphosate-resistant Kochia scoparia

The widely used herbicide glyphosate inhibits the shikimate pathway enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Globally, the intensive use of glyphosate for weed control has selected for glyphosate resistance in 31 weed species. Populations of suspected glyphosate-resistant Kochia scoparia were collected from fields located in the US central Great Plains. Glyphosate dose response verified glyphosate resistance in nine populations. The mechanism of resistance to glyphosate was investigated using targeted sequencing, quantitative PCR, immunoblotting, and whole transcriptome de novo sequencing to characterize the sequence and expression of EPSPS. Sequence analysis showed no mutation of the EPSPS Pro106 codon in glyphosate-resistant K. scoparia, whereas EPSPS genomic copy number and transcript abundance were elevated three- to ten-fold in resistant individuals relative to susceptible individuals. Glyphosate-resistant individuals with increased relative EPSPS copy numbers ha...

广泛使用的除草剂草甘膦（glyphosate）可抑制莽草酸途径（shikimate pathway）中的关键酶5-烯醇丙酮酰莽草酸-3-磷酸合酶（5-enolpyruvylshikimate-3-phosphate synthase，EPSPS）。全球范围内，为防控杂草而大量施用草甘膦，已筛选出31种具有草甘膦抗药性的杂草物种。本研究从美国中部大平原（US central Great Plains）的农田中采集了疑似抗草甘膦的地肤（Kochia scoparia）种群，通过草甘膦剂量响应实验验证，其中9个种群确认为草甘膦抗性种群。为探究该类群的草甘膦抗药性机制，本研究采用靶向测序（targeted sequencing）、定量PCR（quantitative PCR）、免疫印迹（immunoblotting）及全转录组从头测序（whole transcriptome de novo sequencing）等技术，对EPSPS的序列与表达特征进行解析。序列分析结果显示，抗草甘膦地肤的EPSPS基因Pro106密码子未发生突变，但抗性个体的EPSPS基因组拷贝数及转录本丰度较敏感个体提升了3至10倍。相对EPSPS拷贝数升高的抗草甘膦个体……