Data from: Genetic diversity and structure of Lolium perenne ssp. multiflorum in California vineyards and orchards indicates potential for spread of herbicide resistance via gene flow

Management of agroecosystems with herbicides imposes strong selection pressures on weedy plants leading to the evolution of resistance against those herbicides. Resistance to glyphosate in populations of Lolium perenne L. ssp. multiflorum is increasingly common in California, USA, causing economic losses and the loss of effective management tools. To gain insights into the recent evolution of glyphosate resistance in L. perenne in perennial cropping systems of northwest California and to inform management, we investigated the frequency of glyphosate resistance and the genetic diversity and structure of 14 populations. The sampled populations contain frequencies of resistant plants ranging from 10% to 89%. Analyses of neutral genetic variation using microsatellite markers indicated very high genetic diversity within all populations regardless of resistance frequency. Genetic variation was distributed predominantly among individuals within populations rather than among populations or sampled counties, as would be expected for a wide-ranging outcrossing weed species. Bayesian clustering analysis provided evidence of population structuring with extensive admixture between two genetic clusters or gene pools. High genetic diversity and admixture, and low differentiation between populations, strongly suggests the potential for spread of resistance through gene flow and the need for management that limits seed and pollen dispersal in L. perenne.利用除草剂开展农业生态系统管控，会对杂草类植物施加强烈的选择压力，进而促使其演化出针对此类除草剂的抗性。美国加利福尼亚州境内，多花黑麦草（Lolium perenne L. ssp. multiflorum）种群对草甘膦（glyphosate）的抗性案例愈发普遍，不仅造成了经济损失，还导致有效管控手段的失效。为解析美国加利福尼亚州西北部多年生种植系统中多花黑麦草草甘膦抗性的近期演化机制，并为田间管控提供科学依据，本研究对14个种群的草甘膦抗性频率、遗传多样性及种群遗传结构展开了调查。所采样的种群中，抗性植株的频率介于10%至89%之间。利用微卫星标记（microsatellite markers）对中性遗传变异进行分析的结果显示，无论抗性频率如何，所有种群内部均具有极高的遗传多样性。遗传变异主要分布于种群内部的个体之间，而非种群间或采样县域间，这一结果契合广布型异交杂草物种的遗传分化规律。贝叶斯聚类分析（Bayesian clustering analysis）结果显示种群存在遗传结构，且两个遗传簇或基因库间存在广泛的遗传混合。极高的遗传多样性与遗传混合程度，加之种群间极低的遗传分化，均强烈提示抗性可通过基因流（gene flow）快速扩散，因此亟需制定能够限制多花黑麦草种子与花粉扩散的管控策略。