Data from: Recurrent hybridisation events between Primula vulgaris, P. veris and P. elatior (Primulaceae, Ericales) challenge the species boundaries: Using molecular markers to re‐evaluate morphological identifications

Three Primula species, Primula vulgaris, P. veris and P. elatior, have been objects of fascination for gardeners and botanists over several centuries. The species are able to hybridise, and where they co-occur, hybrids are commonly found. In Denmark, Møns Klint on the island of Møn and Købelev Skov on Lolland are examples of localities where all three species occur and where the hybrids P. ×digenea, the hybrid between P. vulgaris and P. elatior, and P. ×polyantha, the hybrid between P. veris and P. vulgaris, can also be found. To investigate relations between the species and their hybrids, 168 specimens from 10 geographical locations were sampled for genetic analysis using DNA markers and identified based on morphological traits, primarily inflorescense structure, the size, shape, colour and markings of corolla and leaf basis, leaf blade texture and hairiness. After identifying species-specific SNPs in the internal transcribed spacer sequence, these were used to resolve species and hybrid boundaries and status through a cleaved amplified polymorphic sequence assay. Polymorphisms in the chloroplast trnL sequence were used as a high-throughput marker and used to determine the maternal parent of hybrids. Ten simple sequence repeat markers were applied to obtain further insight into the genetic makeup of the accessions using Structure and Introgress, providing information of genetic variability within and between populations. Data analyses indicated that backcrossing of P. ×digenea hybrids with parental species has occurred, and that many of the P. ×digenea found in the study were later-generation hybrids rather than F1s. Analyses of P. ×polyantha specimens show mostly the expected pattern for primary hybrids but indications of P. veris ancestry of a P. vulgaris plant was discovered. Our results further indicate that some of the specimens initially identified as P. elatior include P. vulgaris among their progenitors and thus challenge currently accepted species boundaries.

报春花属（Primula）的三个物种——欧报春（Primula vulgaris）、黄花九轮草（Primula veris）与高报春（Primula elatior）——数个世纪以来一直是园艺爱好者与植物学家倾心研究的对象。这三个物种间可发生杂交，在其共同分布区域内，杂交个体较为常见。在丹麦，默恩岛（Møn）的默恩斯崖（Møns Klint）与洛兰岛（Lolland）的克厄莱夫森林（Købelev Skov）即为三个原生物种共同分布的典型区域，此地同时存在两种杂交报春：一是欧报春与高报春的杂交种P. × digenea，二是黄花九轮草与欧报春的杂交种P. × polyantha。为探究三个原生物种及其杂交后代的亲缘关系，研究人员从10个地理区域采集了168份标本，采用DNA标记技术开展遗传分析，并结合形态性状对标本进行鉴定，形态性状主要包括花序结构、花冠与叶基的大小、形状、颜色及斑纹，以及叶片质地与毛被情况。研究人员在内部转录间隔区（internal transcribed spacer, ITS）序列中筛选出物种特异性单核苷酸多态性（single nucleotide polymorphism, SNP）位点，随后通过酶切扩增多态性序列（cleaved amplified polymorphic sequence, CAPS）分析，明确各物种与杂交个体的分类界限及群体地位。研究人员以叶绿体trnL序列多态性作为高通量分子标记，用于确定杂交个体的母本来源。研究人员选用10个简单序列重复（simple sequence repeat, SSR）标记，结合Structure与Introgress两款软件对供试种质材料的遗传构成展开深入分析，以解析种群内部及种群间的遗传变异情况。数据分析结果显示，P. × digenea杂交个体曾与亲本物种发生回交，且本研究中发现的多数P. × digenea均为多代杂交后代，而非F1代杂种。对P. × polyantha标本的分析结果大多符合初级杂交种的预期模式，但研究中同时发现1份欧报春材料携带黄花九轮草的祖先遗传背景。本研究结果还显示，部分最初被鉴定为高报春的标本，其祖先谱系中包含欧报春，这一发现对当前公认的物种分类界限提出了挑战。