Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE, USA.
Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO, USA.
Plant J. 2018 Dec;96(5):1051-1063. doi: 10.1111/tpj.14089. Epub 2018 Oct 23.
Pollen-mediated gene flow (PMGF) might play an important role in dispersing herbicide resistance alleles in dioecious weedy Amaranthus species. Field experiments in a concentric donor-receptor design were conducted to quantify two sets of PMGF studies, an interspecific (Amaranthus tuberculatus × Amaranthus palmeri) and an intraspecific (A. tuberculatus × A. tuberculatus). In both studies, PMGF was evaluated using a resistant A. tuberculatus phenotype with enhanced mesotrione detoxification via P450 enzymes as a source of resistance alleles. For interspecific hybridization, more than 104 000 putative hybrid seedlings were screened with three markers, one phenotypic and two molecular. The two molecular markers used, including 2-bp polymorphisms in the internal transcribed spacer region, distinguished A. palmeri, A. tuberculatus and their hybrids. Results showed that 0.1% hybridization between A. tuberculatus × A. palmeri occurred under field research conditions. For intraspecific hybridization, 22 582 seedlings were screened to assess the frequency of gene flow. The frequency of gene flow (F ) varied with distance, direction and year of the study. The farthest distance for 90% reduction of F was at 69 m in 2015 however, after averaging across directions it was 13.1 and 26.1 m in 2014 and 2015, respectively. This study highlights the transfer of metabolism-based mesotrione resistance from A. tuberculatus to A. palmeri under field research conditions. The results presented here might aid in the rapid detection of A. palmeri among other Amaranthus species and show that PMFG could be expediting the increase of herbicide resistance in A. palmeri and A. tuberculatus across US crop production areas.
花粉介导的基因流（PMGF）可能在分散雌雄异株杂草苋属物种中的除草剂抗性等位基因方面发挥重要作用。在同心供体-受体设计中进行了田间实验，以量化两项 PMGF 研究，一项是种间（Amaranthus tuberculatus×Amaranthus palmeri）和一项是种内（A. tuberculatus×A. tuberculatus）。在这两项研究中，均使用具有增强的通过 P450 酶进行的麦草畏解毒作用的抗性 A. tuberculatus 表型作为抗性等位基因的来源来评估 PMGF。对于种间杂交，使用三个标记物（一个表型标记物和两个分子标记物）筛选了超过 104000 个假定的杂种幼苗。使用的两个分子标记物，包括内部转录间隔区的 2-bp 多态性，可区分 A. palmeri、A. tuberculatus及其杂种。结果表明，在田间研究条件下，A. tuberculatus×A. palmeri 之间发生了 0.1%的杂交。对于种内杂交，筛选了 22582 个幼苗以评估基因流的频率。基因流的频率（F）随距离、方向和研究年份而变化。在 2015 年，F 降低 90%的最远距离为 69m，但在平均方向后，分别为 2014 年和 2015 年的 13.1 和 26.1m。这项研究强调了在田间研究条件下，A. tuberculatus 中代谢基础的麦草畏抗性向 A. palmeri 的转移。这里呈现的结果可能有助于在其他苋属物种中快速检测到 A. palmeri，并表明 PMFG 可能正在加速美国作物生产区 A. palmeri 和 A. tuberculatus 中除草剂抗性的增加。
