As Charles Darwin anticipated, living fossils provide excellent opportunities to study evolutionary questions related to extinction, competition, and adaptation. Ginkgo (Ginkgo bilobaL.) is one of the oldest living plants and a fascinating example of how people have saved a species from extinction and assisted its resurgence. By resequencing 545 genomes of ginkgo trees sampled from 51 populations across the world, we identify three refugia in China and detect multiple cycles of population expansion and reduction along with glacial admixture between relict populations in the southwestern and southern refugia. We demonstrate multiple anthropogenic introductions of ginkgo from eastern China into different continents. Further analyses reveal bioclimatic variables that have affected the geographic distribution of ginkgo and the role of natural selection in ginkgo’s adaptation and resilience. These investigations provide insights into the evolutionary history of ginkgo trees and valuable genomic resources for further addressing various questions involving living fossil species.

The Chinese ginseng Panax notoginseng is a domesticated herb with significant medicinal and economic value. Here we report a chromosome-level P. notoginseng genome assembly with a high (∼79%) repetitive sequence content. The juxtaposition with the widely distributed, closely related Korean ginseng (Panax ginseng) genome revealed contraction of plant defense genes (in particular R-genes) in the P. notoginseng genome. We also investigated the reasons for the larger genome size of Panax species, revealing contributions from two Panax-specific whole-genome duplication events and transposable element expansion. Transcriptome data and comparative genome analysis revealed the candidate genes involved in the ginsenoside synthesis pathway. We also performed a genome-wide association study on 240 cultivated P. notoginseng individuals and identified the associated genes with dry root weight (63 genes) and stem thickness (168 genes). The P. notoginseng genome represents a critical step toward harnessing the full potential of an economically important and enigmatic plant.

At the end of the Pliocene and the beginning of Pleistocene glaciation and deglaciation cycles Ginkgo biloba went extinct all over the world, and only few populations remained in China in relict areas serving as sanctuary for Tertiary relict trees. Yet the status of these regions as refuge areas with naturally existing populations has been proven not earlier than one decade ago. Herein we elaborated the hypothesis that during the Pleistocene cooling periods G. biloba expanded its distribution range in China repeatedly. Whole plastid genomes were sequenced, assembled and annotated, and sequence data was analyzed in a phylogenetic framework of the entire gymnosperms to establish a robust spatio-temporal framework for gymnosperms and in particular for G. biloba Pleistocene evolutionary history. Using a phylogenetic approach, we identified that Ginkgoatae stem group age is about 325 million years, whereas crown group radiation of extant Ginkgo started not earlier than 390,000 years ago. During repeated warming phases, Gingko populations were separated and isolated by contraction of distribution range and retreated into mountainous regions serving as refuge for warm-temperate deciduous forests. Diversification and phylogenetic splits correlate with the onset of cooling phases when Ginkgo expanded its distribution range and gene pools merged. Analysis of whole plastid genome sequence data representing the entire spatio-temporal genetic variation of wild extant Ginkgo populations revealed the deepest temporal footprint dating back to approximately 390,000 years ago. Present-day directional West-East admixture of genetic diversity is shown to be the result of pronounced effects of the last cooling period. Our evolutionary framework will serve as a conceptual roadmap for forthcoming genomic sequence data, which can then provide deep insights into the demographic history of Ginkgo.