Knotweed species in the genus Reynoutria are native to eastern Asia but have become noxious weeds in Europe and North America. In the United States, invasive populations of Japanese knotweed (Reynoutria japonica Houtt.), giant knotweed [Reynoutria sachalinensis (F. Schmidt) Nakai], and their interspecific hybrid known as Bohemian knotweed (R. × bohemica Chrtek & Chrtková) continue to expand their ranges. Although these plants are among the most invasive terrestrial species, there are relatively few molecular tools for identifying the parental species, the F1 hybrid, or subsequent hybrids or introgressed individuals. We studied Reynoutria populations in Wisconsin, a state where all three taxa grow, to determine whether molecular data would be useful for distinguishing species and identifying hybrids. We obtained DNA sequence data from the plastid matK gene and the nuclear LEAFY gene and compared these to previously published sequences. Data from the uniparentally inherited matK region included haplotypes attributable to R. japonica and R. sachalinensis. Nuclear data indicated that R. sachalinensis plants are most similar to native plants in Japan, with two Wisconsin accessions exhibiting a monomorphic genotype for the LEAFY gene. Three Wisconsin accessions of R. japonica were each characterized by having three distinct kinds of LEAFY sequence. Most plants in our study were found to possess two or three phylogenetically distinct copies of the LEAFY gene, with the copies being most closely related to R. japonica and R. sachalinensis, respectively, and these were inferred to be interspecific hybrids. Altogether, five kinds of interspecific hybrids were identified, reflecting various combinations of LEAFY sequence types from the parental species. The widespread existence of hybrid plants in Wisconsin, many of which are morphologically identifiable as R. japonica, indicates a cryptic genetic diversity that should be examined more broadly in North America using molecular tools.

中文翻译：

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利用核叶基因重建入侵虎杖（Reynoutria，Polygonaceae）种群之间的系统发育关系

虎杖属物种雷诺氏菌原产于东亚，但在欧洲和北美已成为有害杂草。在美国，日本虎杖的入侵种群（粳稻Houtt.), 巨型虎杖 [大花犀（F. Schmidt）Nakai]，以及它们的种间杂种，称为波西米亚虎杖（R. × bohemicaChrtek & Chrtková) 继续扩大他们的范围。尽管这些植物是最具入侵性的陆地物种之一，但用于识别亲本物种的分子工具相对较少，F1杂种，或随后的杂种或渗入的个体。我们学习了雷诺氏菌威斯康星州的种群，这是一个所有三个分类群都生长的州，以确定分子数据是否有助于区分物种和识别杂种。我们从质体中获得了 DNA 序列数据垫子基因与核多叶基因并将这些与先前发表的序列进行比较。来自单亲继承的数据垫子区域包括可归因于的单倍型粳稻和R. sachalinensis. 核数据表明R. sachalinensis植物与日本的本土植物最相似，威斯康星州的两个种质表现出单态基因型多叶基因。三个威斯康星州加入粳稻每个都具有三种不同的特征多叶顺序。在我们的研究中，大多数植物被发现拥有两到三个在系统发育上不同的拷贝。多叶基因，其中的拷贝与粳稻和R. sachalinensis，分别，并且这些被推断为种间杂种。总共鉴定出五种种间杂种，反映了多叶来自亲本物种的序列类型。威斯康星州广泛存在杂交植物，其中许多在形态上可识别为粳稻, 表明一种神秘的遗传多样性，应该在北美使用分子工具进行更广泛的检查。