堪萨斯州立大学的一位杂草科学家最近的一项研究发现了为什么入侵性杂草地肤就像植物界的蟑螂。
According to Kansas State, Mithila Jugulam, assistant professor of agronomy, led a study that looked at how kochia — invasive weed populations that are taking over crops and non-crop areas in western Kansas and the Great Plains — evolved resistance to glyphosate. Researchers found that kochia has evolved to have multiple copies of a gene code that targets glyphosate. These copies enable the plants to survive the field rate of glyphosate applications.
“It’s a very novel resistance mechanism and is becoming prevalent in a number of glyphosate-resistant weeds, including Palmer amaranth, common waterhemp and kochia,” Jugulam said.
Jugulam conducted the study in collaboration with Kansas State University’s Bikram Gill, university distinguished professor of plant pathology.
日记 植物生理学 recently published their study, “Tandem Amplification of a Chromosomal Segment Harboring 5-Enolpyruvylshikimate-3-Phosphate Synthase Locus Confers Glyphosate Resistance in 地肤子.” It is the first study to find a molecular cytogenetic basis of EPSPS gene amplification in kochia.
草甘膦的作用是阻止一种叫做 EPSPS 的酶，这种酶对于莽草酸途径中芳香氨基酸的产生至关重要。如果 EPSPS 受到干扰，植物最终会死亡。
使用称为荧光的创新技术 就地 hybridization, or Fiber FISH, on kochia’s DNA fragment, the team found that glyphosate-resistant kochia had duplicated several EPSPS copies that stacked alongside each other on a single chromosome.
研究人员还发现，EPSPS地肤的拷贝数越多，它对草甘膦的耐受性就越高。例如，具有 9 到 12 个 EPSPS 拷贝的地肤植物可以在两倍于推荐量的草甘膦中存活，而具有 16 个拷贝的植物可以承受六倍的草甘膦量。
虽然 EPSPS 基因拷贝的增加创造了一种仅用草甘膦方案控制地肤子的不可持续方式，但 Jugulam 说，这种抗性是由于持续使用草甘膦和控制这种杂草缺乏除草剂多样性而演变而来的。
“Herbicides are not known to cause mutations in plants,” Jugulam said in a statement. “The resistant individuals present in the population initially are at low levels and slowly dominate over the susceptible plants if selection with the same herbicide continues.”
目前，Jugulam 及其同事正在研究美国和加拿大各地的地肤子，以了解世界其他地区的植物是否以同样的方式进化。堪萨斯州说，这可能会阐明未来的控制方法。