Lancaster Environment Centre, Lancaster University, Lancaster, United Kingdom.
Department of Genetics and Genome Biology, Leicester University, Leicester, United Kingdom.
PLoS One. 2022 Jan 7;17(1):e0261742. doi: 10.1371/journal.pone.0261742. eCollection 2022.
Extreme weather and globalisation leave our climate vulnerable to invasion by alien species, which have negative impacts on the economy, biodiversity, and ecosystem services. Rapid and accurate identification is key to the control of invasive alien species. However, visually similar species hinder conservation efforts, for example hybrids within the Japanese Knotweed complex.We applied the novel method of ATR-FTIR spectroscopy combined with chemometrics (mathematics applied to chemical data) to historic herbarium samples, taking 1580 spectra in total. Samples included five species from within the interbreeding Japanese Knotweed complex (including three varieties of Japanese Knotweed), six hybrids and five species from the wider Polygonaceae family. Spectral data from herbarium specimens were analysed with several chemometric techniques: support vector machines (SVM) for differentiation between plant types, supported by ploidy levels; principal component analysis loadings and spectral biomarkers to explore differences between the highly invasive Reynoutria japonica var. japonica and its non-invasive counterpart Reynoutria japonica var. compacta; hierarchical cluster analysis (HCA) to investigate the relationship between plants within the Polygonaceae family, of the Fallopia, Reynoutria, Rumex and Fagopyrum genera.ATR-FTIR spectroscopy coupled with SVM successfully differentiated between plant type, leaf surface and geographical location, even in herbarium samples of varying age. Differences between Reynoutria japonica var. japonica and Reynoutria japonica var. compacta included the presence of two polysaccharides, glucomannan and xyloglucan, at higher concentrations in Reynoutria japonica var. japonica than Reynoutria japonica var. compacta. HCA analysis indicated that potential genetic linkages are sometimes masked by environmental factors; an effect that can either be reduced or encouraged by altering the input parameters. Entering the absorbance values for key wavenumbers, previously highlighted by principal component analysis loadings, favours linkages in the resultant HCA dendrogram corresponding to expected genetic relationships, whilst environmental associations are encouraged using the spectral fingerprint region.The ability to distinguish between closely related interbreeding species and hybrids, based on their spectral signature, raises the possibility of using this approach for determining the origin of Japanese knotweed infestations in legal cases where the clonal nature of plants currently makes this difficult and for the targeted control of species and hybrids. These techniques also provide a new method for supporting biogeographical studies.
极端天气和全球化使我们的气候容易受到外来物种的入侵，这些物种对经济、生物多样性和生态系统服务都有负面影响。快速准确的鉴定是控制入侵外来物种的关键。然而，视觉上相似的物种会阻碍保护工作，例如日本虎杖复合体中的杂种。我们应用新型的衰减全反射傅里叶变换红外光谱结合化学计量学（应用于化学数据的数学）方法，对历史植物标本馆样本进行了研究，总共采集了 1580 个光谱。样本包括日本虎杖复合体（包括三种日本虎杖品种）内的五个物种、六个杂种和 wider Polygonaceae 家族的五个物种。对植物标本馆标本的光谱数据进行了多种化学计量技术分析：支持向量机（SVM）用于区分植物类型，同时支持多倍体水平；主成分分析负荷和光谱生物标志物用于探索高度入侵的日本虎杖（Reynoutria japonica var. japonica）与其非入侵对应物日本虎杖（Reynoutria japonica var. compacta）之间的差异；层次聚类分析（HCA）用于研究Polygonaceae 家族中植物之间的关系，包括 Fallopia、Reynoutria、Rumex 和 Fagopyrum 属。ATR-FTIR 光谱结合 SVM 成功地区分了植物类型、叶片表面和地理位置，即使在不同年代的植物标本馆样本中也是如此。日本虎杖（Reynoutria japonica var. japonica）和日本虎杖（Reynoutria japonica var. compacta）之间的差异包括两种多糖，葡甘露聚糖和木葡聚糖，在日本虎杖（Reynoutria japonica var. japonica）中的浓度高于日本虎杖（Reynoutria japonica var. compacta）。HCA 分析表明，遗传联系有时会被环境因素掩盖；通过改变输入参数，可以减少或促进这种影响。输入主成分分析负荷突出的关键波数的吸光度值有利于对应于预期遗传关系的 HCA 树状图中的连接，而使用光谱指纹区域则有利于鼓励环境关联。根据其光谱特征区分密切相关的杂交种和杂种的能力，提高了在目前由于植物克隆性质而难以确定日本虎杖入侵来源的法律案件中使用这种方法的可能性，并有助于对物种和杂种进行有针对性的控制。这些技术还为生物地理研究提供了一种新方法。
