Physical Mapping of Amplified Copies of the 5-Enolpyruvylshikimate-3-Phosphate Synthase Gene in Glyphosate-Resistant Amaranthus tuberculatus
Physical Mapping of Amplified Copies of the 5-Enolpyruvylshikimate-3-Phosphate Synthase Gene in Glyphosate-Resistant Amaranthus tuberculatus
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DOI：
10.1104/pp.16.01427
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发表时间：
2017-02-01
期刊：
影响因子：
7.4
通讯作者：
Jugulam, Mithila
中科院分区：
文献类型：
--
作者：
Dillon, Andrew;Varanasi, Vijay K.;Jugulam, Mithila
草甘膦是最广泛使用的除草剂，最近在几种杂草中，包括常见的水麻（Amaranthus tuberculatus），对草甘膦的抗性迅速演变，对作物的持续生产构成严重威胁。我们报道了草甘膦抗性在A. tuberculatus的感染是由于5-烯醇式莽草酸-3-P合酶（EPSPS）基因的扩增，该基因编码草甘膦的分子靶标。EPSPS基因拷贝数与其转录本表达量呈正相关。我们分析了EPSPS拷贝数在A.利用荧光原位杂交技术对有丝分裂中期染色体和间期核进行了研究。荧光原位杂交分析将EPSPS基因定位于草甘膦敏感A.具瘤的在抗草甘膦植物中，在一对同源染色体的近着丝粒区域检测到EPSPS基因簇。有趣的是，两个高度抗草甘膦的植物除了具有EPSPS拷贝的天然染色体对之外，还具有具有多个EPSPS拷贝的额外染色体。这些结果表明，EPSPS基因复制的初始事件可能是由于重复DNA介导的不平等重组而发生的。随后，基因扩增可能通过几种其他机制，如染色体重排，缺失/插入，转座子介导的分散，或可能通过种间杂交。本报告说明了扩增的EPSPS拷贝在A.具瘤的
Recent and rapid evolution of resistance to glyphosate, the most widely used herbicides, in several weed species, including common waterhemp (Amaranthus tuberculatus), poses a serious threat to sustained crop production. We report that glyphosate resistance in A. tuberculatus was due to amplification of the 5-enolpyruvylshikimate-3-P synthase (EPSPS) gene, which encodes the molecular target of glyphosate. There was a positive correlation between EPSPS gene copies and its transcript expression. We analyzed the distribution of EPSPS copies in the genome of A. tuberculatus using fluorescence in situ hybridization on mitotic metaphase chromosomes and interphase nuclei. Fluorescence in situ hybridization analysis mapped the EPSPS gene to pericentromeric regions of two homologous chromosomes in glyphosate sensitive A. tuberculatus. In glyphosate-resistant plants, a cluster of EPSPS genes on the pericentromeric region on one pair of homologous chromosomes was detected. Intriguingly, two highly glyphosate-resistant plants harbored an additional chromosome with several EPSPS copies besides the native chromosome pair with EPSPS copies. These results suggest that the initial event of EPSPS gene duplication may have occurred because of unequal recombination mediated by repetitive DNA. Subsequently, gene amplification may have resulted via several other mechanisms, such as chromosomal rearrangements, deletion/insertion, transposon-mediated dispersion, or possibly by interspecific hybridization. This report illustrates the physical mapping of amplified EPSPS copies in A. tuberculatus.