Ministry of Education Key Laboratory of Xinjiang Phytomedicine Resource Utilisation, College of Life Sciences, Shihezi University, Shihezi, Xinjiang 832003, China.
C R Biol. 2020 Jun 5;343(1):63-72. doi: 10.5802/crbiol.7.
Xanthium italicum is an aggressive weed found worldwide. Despite several ecological, morphological, and physiological research on its invasion mechanism, the mechanism of its successful invasion has not been revealed from the viewpoint of population genetics. Thus, we aimed to evaluate the genetic variation within and among populations of the alien invasive weed X. italicum in China, and to provide a theoretical basis for its invasion mechanism. For that, we employed inter-simple sequence repeat (ISSR) markers to explore the genetic diversity and genetic differentiation of 185 individuals sampled from 10 populations. Eight selected primers yielded a total of 76 bright and discernible bands. X. italicum showed an intermediate genetic diversity at the population level (percentage of polymorphic loci (PPL) = 60.26%, Nei's genetic diversity (H) = 0.2098, Shannon's information index (I) = 0.3129). However, the genetic diversity at the species level was significantly high (PPL = 100%; H = 0.3673; I = 0.5425). The coefficient of gene differentiation (GST, 41.4%) and analysis of molecular variance showed that genetic differentiation mainly occurred within populations. The estimated gene flow (Nm, 0.7085) and Mantel test indicated that genetic differentiation in the populations may primarily come from genetic drift and anthropogenic activities. Our results revealed the high genetic diversity of X. italicum, which may help explain its invasion success in China. This knowledge may contribute to the efforts for decreasing and eventually stopping X. italicum invasion in China.
豚草是一种在全世界广泛存在的侵略性杂草。尽管已经对其入侵机制进行了生态、形态和生理等多方面的研究，但从种群遗传学的角度来看，其成功入侵的机制尚未被揭示。因此，我们旨在评估中国外来入侵杂草豚草种群内和种群间的遗传变异，并为其入侵机制提供理论依据。为此，我们采用简单重复间序列（ISSR）标记来探索 10 个种群的 185 个个体的遗传多样性和遗传分化。从 8 个选定的引物中总共产生了 76 个明亮且可分辨的条带。豚草在种群水平上表现出中等程度的遗传多样性（多态性位点百分比（PPL）=60.26%，Nei 遗传多样性（H）=0.2098，Shannon 信息指数（I）=0.3129）。然而，物种水平上的遗传多样性则显著较高（PPL=100%；H=0.3673；I=0.5425）。基因分化系数（GST，41.4%）和分子方差分析表明，遗传分化主要发生在种群内部。估计的基因流（Nm，0.7085）和 Mantel 检验表明，种群间的遗传分化可能主要来自遗传漂变和人为活动。我们的研究结果揭示了豚草具有较高的遗传多样性，这可能有助于解释其在中国的成功入侵。这些知识可能有助于减少甚至最终阻止豚草在中国的入侵。
