This article aims to understand the global and longitudinal trends of research on Panax ginseng. We used bibliometrics to analyze 3974 papers collected from the Web of Science^TM Core Collection database during 1959–2016. The number of publications showed a steady growth before 2000 and exponentially increased in stage III (2000–2016, about 86% of the papers were published). Research on P. ginseng was conducted in 64 countries, mainly in Asia; in particular, 41% and 28% of the publications were from South Korea and China, respectively. The institutions from South Korea and China had high publication output and close cooperation and provided the majority of financial support. All top 10 authors and four of the top 20 journals in terms of number of publications originated from South Korea. The leading research subjects were pharmacology (39%), plant science (26%), and integrative complementary medicine (19%). The hotspot of P. ginseng research transformed from basic science to application, and multidisciplinary sciences will play a substantial role in the future. This study provides a comprehensive analysis to elucidate the global distribution, collaboration patterns, and research trends in the P. ginseng domain.

Background: Cistanche is an important genus of Orobanchaceae, with critical medicinal, economic, and desertification control values. However, the phylogenetic relationships of Cistanche genus remained obscure. To date, no effective molecular markers have been reported to discriminate effectively the Cistanche closely related species reported here. In this study, we obtained and characterized the plastomes of four Cistanche species from China, to clarify the phylogenetic relationship within the genus, and to develop molecular markers for species discrimination. Results: Four Cistanche species (Cistanche deserticola, Cistanche salsa, Cistanche tubulosa and Cistanche sinensis), were deep-sequenced with Illumina. Their plastomes were assembled using SPAdes and annotated using CPGAVAS2. The plastic genomes were analyzed in detail, finding that all showed the conserved quadripartite structure (LSC-IR-SSC-IR) and with full sizes ranging from 75 to 111 Kbp. We observed a significant contraction of small single copy region (SSC, ranging from 0.4–29 Kbp) and expansion of inverted repeat region (IR, ranging from 6–30 Kbp), with C. deserticola and C. salsa showing the smallest SSCs with only one gene (rpl32). Compared with other Orobanchaceae species, Cistanche species showed extremely high rates of gene loss and pseudogenization, as reported for other parasitic Orobanchaceae species. Furthermore, analysis of sequence divergence on protein-coding genes showed the three genes (rpl22, clpP and ycf2) had undergone positive selection in the Cistanche species under study. In addition, by comparison of all available Cistanche plastomes we found 25 highly divergent intergenic spacer (IGS) regions that were used to predict two DNA barcode markers (Cis-mk01 and Cis-mk02 based on IGS region trnR-ACG-trnN-GUU) and eleven specific DNA barcode markers using Ecoprimer software. Experimental validation showed 100% species discrimination success rate with both type of markers. Conclusion: Our findings have shown that Cistanche species are an ideal model to investigate the structure variation, gene loss and pseudogenization during the process of plastome evolution in parasitic species, providing new insights into the evolutionary relationships among the Cistanche species. In addition, the developed DNA barcodes markers allow the proper species identification, ensuring the effective and safe use of Cistanche species as medicinal products.