Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
Sci Rep. 2017 Mar 22;7:44913. doi: 10.1038/srep44913.
Gene flow is an important component in evolutionary biology; however, the role of gene flow in dispersal of herbicide-resistant alleles among weed populations is poorly understood. Field experiments were conducted at the University of Nebraska-Lincoln to quantify pollen-mediated gene flow (PMGF) from glyphosate-resistant (GR) to -susceptible (GS) common waterhemp using a concentric donor-receptor design. More than 130,000 common waterhemp plants were screened and 26,199 plants were confirmed resistant to glyphosate. Frequency of gene flow from all distances, directions, and years was estimated with a double exponential decay model using Generalized Nonlinear Model (package gnm) in R. PMGF declined by 50% at <3 m distance from the pollen source, whereas 90% reduction was found at 88 m (maximum) depending on the direction of the pollen-receptor blocks. Amplification of the target site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), was identified as the mechanism of glyphosate resistance in parent biotype. The EPSPS gene amplification was heritable in common waterhemp and can be transferred via PMGF, and also correlated with glyphosate resistance in pseudo-F progeny. This is the first report of PMGF in GR common waterhemp and the results are critical in explaining the rapid dispersal of GR common waterhemp in Midwestern United States.
基因流是进化生物学的一个重要组成部分；然而，基因流在除草剂抗性等位基因在杂草种群中的扩散中的作用还知之甚少。在内布拉斯加大学林肯分校进行了田间实验，使用同心供体-受体设计来量化草甘膦抗性（GR）到-敏感（GS）普通豚草通过花粉介导的基因流（PMGF）。筛选了超过 130,000 株普通豚草植物，其中 26,199 株被证实对草甘膦具有抗性。使用 R 中的广义非线性模型（gnm 包），通过双指数衰减模型估计了来自所有距离、方向和年份的基因流频率。从花粉源<3 m 的距离处，PMGF 下降了 50%，而取决于花粉-受体块的方向，在 88 m（最大）处发现了 90%的减少。5-烯醇丙酮酰莽草酸-3-磷酸合酶（EPSPS）的靶基因扩增被确定为亲本生物型对草甘膦的抗性机制。EPSPS 基因在普通豚草中可遗传扩增，可通过 PMGF 传递，并且与拟 F 后代中的草甘膦抗性相关。这是首次报道 GR 普通豚草中的 PMGF，研究结果对于解释 GR 普通豚草在美国中西部的快速扩散至关重要。
