Genetic and demographic signatures accompanying the evolution of the selfing syndrome in Daphne kiusiana, an evergreen shrub.

BACKGROUND AND AIMS: The evolution of mating systems from outcrossing to self-fertilization is a common transition in flowering plants. This shift is often associated with the 'selfing syndrome', which is characterized by less visible flowers with functional changes to control outcrossing. In most cases, the evolutionary history and demographic dynamics underlying the evolution of the selfing syndrome remain poorly understood. METHODS: Here, we characterize differences in the demographic genetic consequences and associated floral-specific traits between two distinct geographical groups of a wild shrub, Daphne kiusiana, endemic to East Asia; plants in the eastern region (southeastern Korea and Kyushu, Japan) exhibit smaller and fewer flowers compared to those of plants in the western region (southwestern Korea). Genetic analyses were conducted using nuclear microsatellites and chloroplast DNA (multiplexed phylogenetic marker sequencing) datasets. KEY RESULTS: A high selfing rate with significantly increased homozygosity characterized the eastern lineage, associated with lower levels of visibility and herkogamy in the floral traits. The two lineages harboured independent phylogeographical histories. In contrast to the western lineage, the eastern lineage showed a gradual reduction in the effective population size with no signs of a severe bottleneck despite its extreme range contraction during the last glacial period. CONCLUSIONS: Our results suggest that the selfing-associated morphological changes in D. kiusiana are of relatively old origin (at least 100 000 years ago) and were driven by directional selection for efficient self-pollination. We provide evidence that the evolution of the selfing syndrome in D. kiusiana is not strongly associated with a severe population bottleneck.

The complete chloroplast genome sequence of Ligularia stenocephala (Maxim.) Matsum. & Koidz. (Asteraceae: Senecioneae).

Ligularia stenocephala (Maxim.) Matsum. & Koidz is a widely known edible plant species in Korea. It contains various useful antioxidant compounds and has been developed as a horticultural cultivar blooming showy inflorescence. We report the complete plastid genome (plastome) of Ligularia stenocephala, a collection from Korea. The plastome of L. stenocephala is 151,158 base pairs (bp) long and includes a pair of inverted repeat (IR) regions (24,830 bp each) that are separated by a large single copy (LSC) region (83,265 bp) and a small single copy (SSC) region (18,233 bp). The phylogenetic tree shows that L. stenocephala is closely related to L. fischeri with strong bootstrap support.

Comparative Mitogenomic Analysis Reveals Gene and Intron Dynamics in Rubiaceae and Intra-Specific Diversification in Damnacanthus indicus.

The dynamic evolution of mitochondrial gene and intron content has been reported across the angiosperms. However, a reference mitochondrial genome (mitogenome) is not available in Rubiaceae. The phylogenetic utility of mitogenome data at a species level is rarely assessed. Here, we assembled mitogenomes of six Damnacanthus indicus (Rubiaceae, Rubioideae) representing two varieties (var. indicus and var. microphyllus). The gene and intron content of D. indicus was compared with mitogenomes from representative angiosperm species and mitochondrial contigs from the other Rubiaceae species. Mitogenome structural rearrangement and sequence divergence in D. indicus were analyzed in six individuals. The size of the mitogenome in D. indicus varied from 417,661 to 419,435 bp. Comparing the number of intact mitochondrial protein-coding genes in other Gentianales taxa (38), D. indicus included 32 genes representing several losses. The intron analysis revealed a shift from cis to trans splicing of a nad1 intron (nad1i728) in D. indicus and it is a shared character with the other four Rubioideae taxa. Two distinct mitogenome structures (type A and B) were identified. Two-step direct repeat-mediated recombination was proposed to explain structural changes between type A and B mitogenomes. The five individuals from two varieties in D. indicus diverged well in the whole mitogenome-level comparison with one exception. Collectively, our study elucidated the mitogenome evolution in Rubiaceae along with D. indicus and showed the reliable phylogenetic utility of the whole mitogenome data at a species-level evolution.

The complete plastid genome sequence of Vaccinium japonicum (Ericales: Ericaceae), a deciduous broad-leaved shrub endemic to East Asia.

We here sequenced the complete plastid genome (plastome) of Vaccinium japonicum (Ericaceae), a deciduous broad-leaved shrub endemic to East Asia. This species has considerable practical economic value. The plastome of V. japonicum is assembled as a single contig (187,213 bp). A large single copy (104,637 bp) and a small single copy (3,000 bp) of the genome are separated by a pair of inverted repeats (39,788 bp). The genome consists of 135 genes, which include 88 protein coding, eight ribosomal RNA, and 39 transfer RNA genes. The plastome of V. japonicum is similar to that of Vaccinium macrocarpon in gene content and order. Our phylogenetic analysis revealed the phylogenetic position of V. japonicum in a highly supported clade of the genus Vaccinium together with other four congeners, V. bracteatum, V. vitis-idaea, V. uliginosum and V. macrocarpon.

The complete plastid genome sequence of Quercus acuta (Fagaceae), an evergreen broad-leaved oak endemic to East Asia.

We are reporting the complete plastid genome (plastome) of Quercus acuta, an evergreen broad-leaved oak endemic to East Asia. This species is important for maintaining the warm-temperate evergreen forest biome in East Asia. The Q. acuta plastome is 160,522 base pairs (bp) long, with two inverted repeat (IR) regions (25,839 bp each) that separate a large single copy (LSC) region (90,199 bp) and a small single copy (SSC) region (18,645 bp). The phylogenetic tree shows that Quercus acuta is closely related to Quercus sichourensis with strong bootstrap support.

Rear-edge, low-diversity, and haplotypic uniformity in cold-adapted Bupleurum euphorbioides interglacial refugia populations.

The high genetic diversity of rear-edge refugia populations is predicted to have resulted from species repeatedly migrating to low latitudes during glacial periods over the course of Quaternary climate change. However, several recent empirical studies of cold-tolerant plants revealed the opposite pattern. We investigated whether current habitats of the cold-adapted and range-restricted Bupleurum euphorbioides in the Baekdudaegan, South Korea, and North Korea could be interglacial refugia, and documented how their rear-edge populations differ genetically from those of typical temperate species. Phylogeographic analysis and ecological niche modeling (ENM) were used. The genetic structure was analyzed using microsatellite markers and chloroplast DNA sequences. The congener B. longiradiatum was included as a typical temperate plant species. Despite having almost identical life history traits, these congeneric species exhibited contrasting patterns of genetic diversity. ENM revealed an apparent maximum range contraction during the last interglacial. In contrast, its range expanded northward to the Russian Far East (Primorsky) during the Last Glacial Maximum. Thus, we hypothesize that B. euphorbioides retreated to its current refugia during interglacial periods. Unlike populations in the central region, the rear-edge populations were genetically impoverished and uniform, both within populations and in pooled regional populations. The rear-edge B. euphorbioides survived at least one past interglacial, contributing to the species' genetic diversity. We believe that such genetic variation in the cold-adapted B. euphorbioides gives the species the necessary adaptations to survive an upcoming favorable environment (the next glacial), unless there is artificial environmental change.

A Disjunctive Marginal Edge of Evergreen Broad-Leaved Oak (Quercus gilva) in East Asia: The High Genetic Distinctiveness and Unusual Diversity of Jeju Island Populations and Insight into a Massive, Independent Postglacial Colonization.

Jeju Island is located at a marginal edge of the distributional range of East Asian evergreen broad-leaved forests. The low genetic diversity of such edge populations is predicted to have resulted from genetic drift and reduced gene flow when compared to core populations. To test this hypothesis, we examined the levels of genetic diversity of marginal-edge populations of Quercus gilva, restricted to a few habitats on Jeju Island, and compared them with the southern Kyushu populations. We also evaluated their evolutionary potential and conservation value. The genetic diversity and structure were analyzed using 40 polymorphic microsatellite markers developed in this study. Ecological Niche Modeling (ENM) has been employed to develop our insights, which can be inferred from historical distribution changes. Contrary to our expectations, we detected a similar level of genetic diversity in the Jeju populations, comparable to that of the southern Kyushu populations, which have been regarded as long-term glacial refugia with a high genetic variability of East Asian evergreen trees. We found no signatures of recent bottlenecks in the Jeju populations. The results of STRUCTURE, neighbor-joining phylogeny, and Principal Coordinate Analysis (PCoA) with a significant barrier clearly demonstrated that the Jeju and Kyushu regions are genetically distinct. However, ENM showed that the probability value for the distribution of the trees on Jeju Island during the Last Glacial Maximum (LGM) converge was zero. In consideration of these results, we hypothesize that independent massive postglacial colonization from a separate large genetic source, other than Kyushu, could have led to the current genetic diversity of Jeju Island. Therefore, we suggest that the Jeju populations deserve to be separately managed and designated as a level of management unit (MU). These findings improve our understanding of the paleovegetation of East Asian evergreen forests, and the microevolution of oaks.

The complete chloroplast genome sequence of Taxillus yadoriki (Loranthaceae): a hemi-parasitic evergreen shrub in East Asia.

Taxillus yadoriki (Loranthaceae) is a hemiparasitic evergreen shrub distributed in Korea and Japan. We report the complete chloroplast genome of T. yadoriki to provide insight into the phylogenetic relationship of Loranthaceae. This genome is 122,192 bp long, with two IR regions (22,756 bp each) that separate a large single-copy (LSC) region (70,628 bp) and a small single-copy (SSC) region (6052 bp). It contains 109 genes that encode 68 proteins, 8 rRNAs, and 33 tRNAs. All of ndh genes have been lost and the SSC region consists of only four genes similar to other Taxillus species. In ML phylogenetic, monophyly of Taxillus was strongly supported with high bootstrap value and formed a sister group with Scurrula.

The complete chloroplast genome of hemi-parasitic Pedicularis hallaisanensis (Orobanchaceae).

We determined the complete chloroplast genome of Pedicularis hallaisanensis (Orobanchaceae), a hemi-parasitic perennial herb. This genome is 143,469 bp long and features a large single-copy region (81,664 bp) and a small single-copy region (12,203 bp), separated by two inverted-repeat regions (24,801 bp each). It contains 115 genes - 70 for coding, eight for rRNA, and 37 for tRNA. However, 11 ndh genes have been pseudogenized, truncated, or deleted. Our phylogenetic tree showed that these hemi-parasitic plants are sister to holo-parasitic genera within Orobanchaceae.

The complete chloroplast genome of Sarcandra glabra (Chloranthaceae): a perianthless basal angiosperm.

We have obtained the complete chloroplast (cp) genome sequence for Sarcandra glabra. This genome is 158,881 bp long, with 39.2% GC content. It includes a large single copy region of 88,169 bp that is separated from the 18,446-bp small single copy region by two inverted repeat regions (26,133 bp each). This genome contains 130 genes, i.e. 85 protein-coding genes, 37 tRNA, and eight tRNA. Maximum likelihood analysis, based on 13 complete cp genomes, showed that S. glabra is closely related to two other family members, Chloranthus spicatus and C. japonicus.

The complete chloroplast genome sequence of Viburnum Japonicum (Adoxaceae), an evergreen broad-leaved shrub.

The wax-leafed Viburnum japonicum (Adoxaceae) is an evergreen shrub distributed in Japan, Korea, and Taiwan. We sequenced its complete chloroplast (cp) genome to examine its phylogenetic relationship within Dipsacales. This genome is 158,614 bp long and features a large single-copy region (87,059 bp) and a small single-copy region (18,523 bp), separated by two inverted-repeat regions (26,516 bp each). It contains 128 genes, including 84 coding genes, eight rRNAs, and 36 tRNAs. The overall GC content is 38.1%. Our phylogenetic tree showed that V. japonicum is closely related to V. utile and is clustered together with four species in the family Adoxaceae.

Isolation and characterization of 28 microsatellite loci for a Korean endemic, Lespedeza maritima (Fabaceae).

PREMISE OF THE STUDY: We developed microsatellite primers for Lespedeza maritima (Fabaceae), a Korean endemic shrub, and conducted cross-amplifications for closely related species. METHODS AND RESULTS: We produced 28 polymorphic microsatellite markers through reference mapping of 300-bp paired-end reads obtained from Illumina MiSeq data. For 47 individual plants from two populations, the total alleles numbered two to 13, and observed and expected heterozygosities ranged from 0.067 to 0.867 and from 0.064 to 0.848, respectively. Most of these markers were well amplified in closely related species. CONCLUSIONS: In future research, the microsatellite markers described here will help reveal the taxonomic entity of this species.

Development of microsatellite markers for the endangered Pedicularis ishidoyana (Orobanchaceae) using next-generation sequencing.

PREMISE OF THE STUDY: Microsatellite primers were developed for Pedicularis ishidoyana (Orobanchaceae), an endangered and hemiparasitic plant that is narrowly endemic to Korea. Because its populations are threatened by loss of suitable habitat, conservation efforts are required. METHODS AND RESULTS: We developed polymorphic microsatellite loci through reference mapping of 300-bp paired-end reads obtained from Illumina MiSeq data. In all, 74 primer pairs were designed and 32 were amplified. Of these, 18 pairs were polymorphic, with two to six alleles each occurring in 26 individual plants. Expected and observed heterozygosities ranged from 0.142 to 0.703 and from 0.077 to 0.615, respectively. CONCLUSIONS: These microsatellite markers are expected to be useful for studies of the population genetics of P. ishidoyana.