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Cymbidium (Orchidaceae: Epidendroideae), with around 60 species, is widely-distributed across Southeast Asia, providing a nice system for studying the processes that underlie patterns of biodiversity in the region. However, phylogenetic relationships of Cymbidium have not been well resolved, hampering investigations of species diversification and the biogeographical history of this genus. In this study, we construct a plastome phylogeny of 56 Cymbidium species, with four well-resolved major clades, which provides a framework for biogeographical and diversification rate analyses. Molecular dating and biogeographical analyses show that Cymbidium likely originated in the region spanning northern Indo-Burma to the eastern Himalayas during the early Miocene (∼21.10 Ma). It then rapidly diversified into four major clades in East Asia within approximately a million years during the middle Miocene. Cymbidium spp. migration to the adjacent regions (Borneo, Philippines, and Sulawesi) primarily occurred during the Pliocene-Pleistocene period. Our analyses indicate that the net diversification rate of Cymbidium has decreased since its origin, and is positively associated with changes in temperature and monsoon intensity. Favorable hydrothermal conditions brought by monsoon intensification in the early Miocene possibly contributed to the initial rapid diversification, after which the net diversification rate was reduced with the cooling climate after the middle Miocene. The transition from epiphytic to terrestrial habits may have enabled adaptation to cooler environments and colonization of northern niches, yet without a significant effect on diversification rates. This study provides new insights into how monsoon activity and temperature changes affected the diversification dynamics of plants in Southeast Asia.

Pseudosasa gracilis (Poaceae: Bambusoideae) is a temperate woody bamboo species endemic to South-central China with a narrow distribution. Previous phylogenetic studies revealed an unexpected, isolated phylogenetic position of Ps. gracilis. Here we conducted phylogenomic analysis by sampling populations of Ps. gracilis and its sympatric species Ps. nanunica and Sinosasa polytricha reflecting different genomic signals, by deep genome skimming. Integrating molecular evidence from chloroplast genes and genome-wide SNPs, we deciphered the phylogenetic relationships of Ps. gracilis. Both plastid and nuclear data indicate that Ps. gracilis is more closely related to Sinosasa, which is discordant with the taxonomic treatment. To further explore this molecular-morphological conflict, we screened 411 “perfect-copy” syntenic genes to reconstruct phylogenies using both the concatenation and coalescent methods. We observed extensive discordance between gene trees and the putative species tree. A significant hybridization event was detected based on 411 genes from the D subgenome, showing Ps. gracilis was a hybrid descendant between Sinosasa longiligulata and Ps. nanunica, with 63.56% and 36.44% inheritance probabilities of each parent. Moreover, introgression events were detected in the C subgenome between Ps. gracilis and S. polytricha in the same distribution region. Our findings suggest that sympatric hybridization and introgression play a crucial role in the origin of Ps. gracilis. By providing an empirical example of bamboo of hybrid origin using comprehensive analyses based on genomic data from different inheritance systems and morphological characters, our study represents a step forward in understanding of reticulate evolution of bamboos.

Abstract Background The plastid is the photosynthetic organelle in plant cell, and the plastid genomes (plastomes) are generally conserved in evolution. As one of the most economically and ecologically important order of angiosperms, Poales was previously documented to exhibit great plastomic variation as an order of photoautotrophic plants. Results We acquired 93 plastomes, representing all the 16 families and 5 major clades of Poales to reveal the extent of their variation and evolutionary pattern. Extensive variation including the largest one in monocots with 225,293 bp in size, heterogeneous GC content, and a wide variety of gene duplication and loss were revealed. Moreover, rare occurrences of three inverted repeat (IR) copies in angiosperms and one IR loss were observed, accompanied by short IR (sIR) and small direct repeat (DR). Widespread structural heteroplasmy, diversified inversions, and unusual genomic rearrangements all appeared in Poales, occasionally within a single species. Extensive repeats in the plastomes were found to be positively correlated with the observed inversions and rearrangements. The variation all showed a “small-large-moderate” trend along the evolution of Poales, as well as for the sequence substitution rate. Finally, we found some positively selected genes, mainly in C4 lineages, while the closely related lineages of those experiencing gene loss tended to have undergone more relaxed purifying selection. Conclusions The variation of plastomes in Poales may be related to its successful diversification into diverse habitats and multiple photosynthetic pathway transitions. Our order-scale analyses revealed unusual evolutionary scenarios for plastomes in the photoautotrophic order of Poales and provided new insights into the plastome evolution in angiosperms as a whole.

Abstract Poaceae members shared a whole-genome duplication called rho. However, little is known about the evolutionary pattern of the rho-derived duplicates among Poaceae lineages and implications in adaptive evolution. Here we present phylogenomic/phylotranscriptomic analyses of 363 grasses covering all 12 subfamilies and report nine previously unknown whole-genome duplications. Furthermore, duplications from a single whole-genome duplication were mapped to multiple nodes on the species phylogeny; a whole-genome duplication was likely shared by woody bamboos with possible gene flow from herbaceous bamboos; and recent paralogues of a tetraploid Oryza are implicated in tolerance of seawater submergence. Moreover, rho duplicates showing differential retention among subfamilies include those with functions in environmental adaptations or morphogenesis, including ACOT for aquatic environments (Oryzoideae), CK2β for cold responses (Pooideae), SPIRAL1 for rapid cell elongation (Bambusoideae), and PAI1 for drought/cold responses (Panicoideae). This study presents a Poaceae whole-genome duplication profile with evidence for multiple evolutionary mechanisms that contribute to gene retention and losses.

Chinese Assam tea (Camellia sinensis var. assamica) is an important tea crop with a long history of cultivation in Yunnan, China. Despite its potential value as a genetic resource, its genetic diversity and domestication/breeding history remain unclear. To address this issue, we genotyped 469 ancient tea plant trees representing 26 C. sinensis var. assamica populations, plus two of its wild relatives (six and three populations of C. taliensis and C. crassicolumna, respectively) using 16 nuclear microsatellite loci. Results showed that Chinese Assam tea has a relatively high, but comparatively lower gene diversity (HS = 0.638) than the wild relative C. crassicolumna (HS = 0.658). Clustering in STRUCTURE indicated that Chinese Assam tea and its two wild relatives formed distinct genetic groups, with considerable interspecific introgression. The Chinese Assam tea accessions clustered into three gene pools, corresponding well with their geographic distribution. However, NewHybrids analysis indicated that 68.48% of ancient Chinese Assam tea plants from Xishuangbanna were genetic intermediates between the Puer and Lincang gene pools. In addition, 10% of the ancient Chinese Assam tea individuals were found to be hybrids between Chinese Assam tea and C. taliensis. Our results suggest that Chinese Assam tea was domesticated separately in three gene pools (Puer, Lincang and Xishuangbanna) in the Mekong River valley and that the hybrids were subsequently selected during the domestication process. Although the domestication history of Chinese Assam tea in southwestern Yunnan remains complex, our results will help to identify valuable genetic resources that may be useful in future tea breeding programs.

Dryopteris jinpingensis, a new species of diploid, sexually reproductive ferns of Dryopteridaceae from Yunnan, southwestern China, is described and illustrated. Morphologically, D. jinpingensis is similar to D. gaoligongensis but unique in elongated lanceolate laminae, sessile or subsessile pinna stalks, and overlapping membranous scales adnate to stipe base. Phylogenetic analyses based on both plastome and the nuclear AK1 gene sequences showed that D. jinpingensis is sister to D. gaoligongensis. A detailed taxonomic description with line drawings is provided, and its conservation status is evaluated to be critically endangered.

Abstract Background Independent origins of carnivory in multiple angiosperm families are fabulous examples of convergent evolution using a diverse array of life forms and habitats. Previous studies have indicated that carnivorous plants have distinct evolutionary trajectories of plastid genome (plastome) compared to their non-carnivorous relatives, yet the extent and general characteristics remain elusive. Results We compared plastomes from 9 out of 13 carnivorous families and their non-carnivorous relatives to assess carnivory-associated evolutionary patterns. We identified inversions in all sampled Droseraceae species and four species of Utricularia, Pinguicula, Darlingtonia and Triphyophyllum. A few carnivores showed distinct shifts in inverted repeat boundaries and the overall repeat contents. Many ndh genes, along with some other genes, were independently lost in several carnivorous lineages. We detected significant substitution rate variations in most sampled carnivorous lineages. A significant overall substitution rate acceleration characterizes the two largest carnivorous lineages of Droseraceae and Lentibulariaceae. We also observe moderate substitution rates acceleration in many genes of Cephalotus follicularis, Roridula gorgonias, and Drosophyllum lusitanicum. However, only a few genes exhibit significant relaxed selection. Conclusion Our results indicate that the carnivory of plants have different effects on plastome evolution across carnivorous lineages. The complex mechanism under carnivorous habitats may have resulted in distinctive plastome evolution with conserved plastome in the Brocchinia hechtioides to strongly reconfigured plastomes structures in Droseraceae. Organic carbon obtained from prey and the efficiency of utilizing prey-derived nutrients might constitute possible explanation.

Five new orchid species from southwestern China’s Yunnan Province and the Tibetan Autonomous Region, Neottia lihengiae, Neottia chawalongensis, Papilionanthe motuoensis, Gastrochilus lihengiae, and Gastrochilus bernhardtianus, are described and illustrated. To confirm their identities, and to resolve phylogenetic relationships, we sequenced the complete plastomes of these taxa with their congeneric species, adding new plastomes of three Neottia species, two Papilionanthe species and nine Gastrochilus species. Combined with published plastid sequences, our well-resolved phylogeny supported the alliance of N. lihengiae with the the N. grandiflora + N. pinetorum clade. Neottia chawalongensis is now sister to N. alternifolia, while P. motuoensis is closely related to P. subulata + P. teres. Conversely, phylogenetic analyses based on complete plastomes and plastid sequences showed inconsistent relationships among taxa in the genus Gastrochilus, but the two new species, G. lihengiae and G. bernhardtianus were supported by all datasets.

Sex-biased genes offer insights into the evolution of sexual dimorphism. Sex-biased genes, especially those with male bias, show elevated evolutionary rates of protein sequences driven by positive selection and relaxed purifying selection in animals. Although rapid sequence evolution of sex-biased genes and evolutionary forces have been investigated in animals and brown algae, less is known about evolutionary forces in dioecious angiosperms. In this study, we separately compared the expression of sex-biased genes between female and male floral buds and between female and male flowers at anthesis in dioecious Trichosanthes pilosa (Cucurbitaceae). In floral buds, sex-biased gene expression was pervasive, and had significantly different roles in sexual dimorphism such as physiology. We observed higher rates of sequence evolution for male-biased genes in floral buds compared to female-biased and unbiased genes. Male-biased genes under positive selection were mainly associated with functions to abiotic stress and immune responses, suggesting that high evolutionary rates are driven by adaptive evolution. Additionally, relaxed purifying selection may contribute to accelerated evolution in male-biased genes generated by gene duplication. Our findings, for the first time in angiosperms, suggest evident rapid evolution of male-biased genes, advance our understanding of the patterns and forces driving the evolution of sexual dimorphism in dioecious plants.

Fargesia, the largest genus within the temperate bamboo tribe Arundinarieae, has more than 90 species mainly distributed in the mountains of Southwest China. The Fargesia bamboos are important components of the subalpine forest ecosystems that provide food and habitat for many endangered animals, including the giant panda. However, species-level identification of Fargesia is difficult. Moreover, the rapid radiation and slow molecular evolutionary rate of Fargesia pose a significant challenge to using DNA barcoding with standard plant barcodes (rbcL, matK, and ITS) in bamboos. With progress in the sequencing technologies, complete plastid genomes (plastomes) and nuclear ribosomal DNA (nrDNA) sequences have been proposed as organelle barcodes for species identification; however, these have not been tested in bamboos. We collected 196 individuals representing 62 species of Fargesia to comprehensively evaluate the discriminatory power of plastomes and nrDNA sequences compared to standard barcodes. Our analysis indicates that complete plastomes have substantially higher discriminatory power (28.6%) than standard barcodes (5.7%), whereas nrDNA sequences show a moderate improvement (65.4%) compared to ITS (47.2%). We also found that nuclear markers performed better than plastid markers, and ITS alone had higher discriminatory power than complete plastomes. The study also demonstrated that plastomes and nrDNA sequences can contribute to intrageneric phylogenetic resolution in Fargesia. However, neither of these sequences were able to discriminate all the sampled species, and therefore, more nuclear markers need to be identified.

Three woody bamboo species collected in Hainan, China in 1940 have been described as Dinochloa based on vegetative specimens. However, the identity of these species has long been in doubt, largely because the vegetative phase in species of Dinochloa is morphologically similar to that in species of Melocalamus, a climbing or scrambling bamboo genus of the paleotropical woody bamboos (Poaceae: Bambusoideae) that consists of about 15 species and one variety. To determine the phylogenetic affinity of the three Dinochloa species from Hainan, we sampled almost all recognized Chinese species of Melocalamus and representative species of Dinochloa as well as other closely related genera, performed molecular phylogenetic analysis, and compared their morphology based on herbarium and fieldwork investigation. Our ddRAD data indicate that the three species from Hainan are closely related to Melocalamus, not Dinochloa. Morphological analysis showed that these three species have a climbing habit but do not grow spirally, their culm leaves have smooth bases, and there is a ring of powder and/or tomenta above and below the nodes. Taken together our findings indicate that the three species from Hainan originally published in Dinochloa should be transferred to Melocalamus, i.e., Melocalamus orenudus (McClure) D.Z. Li & J.X. Liu, Melocalamus puberulus (McClure) D.Z. Li & J.X. Liu, and Melocalamus utilis (McClure) D.Z. Li & J.X. Liu, respectively. This study concludes with an enumeration of Chinese species of Melocalamus, with a key to nine recognized species and one variety, and a lectotypification for M. compatiflorus.

The Hickeliinae (Poaceae: Bambusoideae) is an ecologically and economically significant subtribe of tropical bamboos restricted to Madagascar, Comoros, Reunion Island, and a small part of continental Africa (Tanzania). Because these bamboos rarely flower, field identification is challenging, and inferring the evolutionary history of Hickeliinae from herbarium specimens is even more so. Molecular phylogenetic work is critical to understanding this group of bamboos. Here, comparative analysis of 22 newly sequenced plastid genomes showed that members of all genera of Hickeliinae share evolutionarily conserved plastome structures. We also determined that Hickeliinae plastome sequences are informative for phylogenetic reconstructions. Phylogenetic analysis showed that all genera of Hickeliinae are monophyletic, except for Nastus, which is paraphyletic and forms two distant clades. The type species of Nastus (Clade II) is endemic to Reunion Island and is not closely related to other sampled species of Nastus endemic to Madagascar (Clade VI). Clade VI (Malagasy Nastus) is sister to the Sokinochloa + Hitchcockella clade (Clade V), and both clades have a clumping habit with short-necked pachymorph rhizomes. The monotypic Decaryochloa is remarkable in having the longest floret in Bambuseae and forms a distinct Clade IV. Clade III, which has the highest generic diversity, consists of Cathariostachys, Perrierbambus, Sirochloa, and Valiha, which are also morphologically diverse. This work provides significant resources for further genetic and phylogenomic studies of Hickeliinae, an understudied subtribe of bamboo.

The taxonomy of the Sino-Himalayan alpine bamboos is controversial due to their complex evolutionary history and further complicated by the scarcity of inflorescence. Here, we supplement the description of the inflorescence of Fargesia angustissima T.P. Yi and Yushania pauciramificans T.P. Yi, which shed light on the taxonomy of Fargesia Franchet, Borinda Stapleton and Yushania Keng. F. angustissima has compressed inflorescence unilateral stretching out from reduced spathe, showing a transitional state between species with condensed inflorescence embraced by spathe-like bracts and species with open inflorescence without bracts. Considering that extensive gene flow existed between several clades of Fargesia found in recent studies, a broadly-defined Fargesia s. l. should be adopted. Meanwhile, the inflorescence of Y. pauciramificans has typical characteristics of Yushania, such as axilla with tuberculate glands, rachilla internodes ciliate and cylindrical florets, supporting the delimitation of Yushania.

Abstract Background Polypodiales suborder Dennstaedtiineae contain a single family Dennstaedtiaceae, eleven genera, and about 270 species, and include some groups that were previously placed in Dennstaedtiaceae, Hypolepidaceae, Monachosoraceae, and Pteridaceae. The classification and phylogenetic relationships among these eleven genera have been poorly understood. To explore the deep relationships within suborder Dennstaedtiineae and estimate the early diversification of this morphologically heterogeneous group, we analyzed complete plastomes of 57 samples representing all eleven genera of suborder Dennstaedtiineae using maximum likelihood and Bayesian inference. Results The phylogenetic relationships of all the lineages in the bracken fern family Dennstaedtiaceae were well resolved with strong support values. All six genera of Hypolepidoideae were recovered as forming a monophyletic group with full support, and Pteridium was fully supported as sister to all the other genera in Hypolepidoideae. Dennstaedtioideae (Dennstaedtia s.l.) fell into four clades with full support: the Microlepia clade, the northern Dennstaedtia clade, the Dennstaedtia globulifera clade, and the Dennstaedtia s.s. clade. Monachosorum was strongly resolved as sister to all the remaining genera of suborder Dennstaedtiineae. Based on the well resolved relationships among genera, the divergence between Monachosorum and other groups of suborder Dennstaedtiineae was estimated to have occurred in the Early Cretaceous, and all extant genera (and clades) in Dennstaedtiineae, were inferred to have diversified since the Late Oligocene. Conclusion This study supports reinstating a previously published family Monachosoraceae as a segregate from Dennstaedtiaceae, based on unique morphological evidence, the shady habitat, and the deep evolutionary divergence from its closest relatives.

Lobelia species, as rich source of the alkaloid lobeline which has been shown to have important biological activity, have been used in folk medicine throughout East Asia to treat various diseases. However, Lobelia is a complex and varied genus in East Asia and is thus difficult to identify. Genomic resources would aid identification, however the availability of such information is poor, preventing a clear understanding of their evolutionary history from being established. To close this gap in the available genomic data, in this study, 17 plastomes of East Asian lobelias were newly sequenced and assembled. Although the plastomes of Lobelia sect. Hypsela, L. sect. Speirema, and L. sect. Rhynchopetalum shared the gene structure, the inverted repeat (IR)/large single copy (LSC) boundaries, genome size, and the number of repeats were variable, indicating the non-conservative nature of plastome evolution within these sections. However, the genomes of the Lobelia sect. Delostemon and L. sect. Stenotium showed rearrangements, revealing that these two sections might have undergone different evolutionary histories. We assessed nine hotspot genes and 27-51 simple sequence repeat motifs, which will also serve as valuable DNA barcode regions in future population genetics studies and for the delineation of plant species. Our phylogenetic analysis resolved the evolutionary positions of the five sections in agreement with previous evolutionary trees based on morphological features. Although phylogenetic reconstruction of Lobelioideae based on the rpoC2 gene has rarely been performed, our results indicated that it contains a considerable amount of phylogenetic information and offers great promise for further phylogenetic analysis of Lobelioideae. Our site-specific model identified 173 sites under highly positive selections. The branch-site model exhibited 11 positive selection sites involving four genes in the East Asian branches. These four genes may play critical roles in the adaptation of East Asian taxa to diverse environments. Our study is the first to detect plastome organization, phylogenetic utility, and signatures of positive selection in the plastomes of East Asian lobelias, which will help to further advance taxonomic and evolutionary studies and the utilization of medicinal plant resources.

Selection along environmental gradients may play a vital role in driving adaptive evolution. Nevertheless, genomic variation and genetic adaptation along environmental clines remains largely unknown in plants in alpine ecosystems. To close this knowledge gap, we assayed transcriptomic profiles of late flower bud and early leaf bud of Rhododendron sanguineum var. haemaleum from four different elevational belts between 3,000 m and 3,800 m in the Gaoligong Mountains. By comparing differences in gene expression of these samples, a gene co-expression network (WGCNA) was constructed to identify candidate genes related to elevation. We found that the overall gene expression patterns are organ-specific for the flower and leaf. Differentially expressed unigenes were identified in these organs. In flowers, these were mainly related to terpenoid metabolism (RsHMGR, RsTPS), while in leaves mainly related to anthocyanin biosynthesis (RsCHS, RsF3’5’H). Terpenoids are the main components of flower scent (fragrance) likely attracting insects for pollination. In response to fewer pollinators at higher elevation zone, it seems relatively less scent is produced in flower organs to reduce energy consumption. Secondary metabolites in leaves such as anthocyanins determine the plants’ alternative adaptive strategy to extreme environments, such as selective pressures of insect herbivory from environmental changes and substrate competition in biosynthesis pathways at high elevations. Our findings indicated that the gene expression profiles generated from flower and leaf organs showed parallel expression shifts but with different functionality, suggesting the existence of flexibility in response strategies of plants exposed to heterogeneous environments across elevational gradients. The genes identified here are likely to be involved in the adaptation of the plants to these varying mountainous environments. This study thus contributes to our understanding of the molecular mechanisms of adaptation in response to environmental change.

Abstract Background Understanding the processes governing angiosperm seed growth and development is essential both for fundamental plant biology and for agronomic purposes. Master regulators of angiosperm seed development are expressed in a seed-specific manner. However, it is unclear how this seed specificity of transcription is established. In some vertebrates, DNA methylation valleys (DMVs) are highly conserved and strongly associated with key developmental genes, but comparable studies in plants are limited to Arabidopsis and soybean. Castor bean (Ricinus communis) is a valuable model system for the study of seed biology in dicots and source of economically important castor oil. Unlike other dicots such as Arabidopsis and soybean, castor bean seeds have a relatively large and persistent endosperm throughout seed development, representing substantial structural differences in mature seeds. Here, we performed an integrated analysis of RNA-seq, whole-genome bisulfite sequencing, and ChIP-seq for various histone marks in the castor bean. Results We present a gene expression atlas covering 16 representative tissues and identified 1162 seed-specific genes in castor bean (Ricinus communis), a valuable model for the study of seed biology in dicots. Upon whole-genome DNA methylation analyses, we detected 32,567 DMVs across five tissues, covering ~33% of the castor bean genome. These DMVs are highly hypomethylated during development and conserved across plant species. We found that DMVs have the potential to activate transcription, especially that of tissue-specific genes. Focusing on seed development, we found that many key developmental regulators of seed/endosperm development, including AGL61, AGL62, LEC1, LEC2, ABI3, and WRI1, were located within DMVs. ChIP-seq for five histone modifications in leaves and seeds clearly showed that the vast majority of histone modification peaks were enriched within DMVs, and their remodeling within DMVs has a critical role in the regulation of seed-specific gene expression. Importantly, further experiment analysis revealed that distal DMVs may act as cis-regulatory elements, like enhancers, to activate downstream gene expression. Conclusions Our results point to the importance of DMVs and special distal DMVs behaving like enhancers, in the regulation of seed-specific genes, via the reprogramming of histone modifications within DMVs. Furthermore, these results provide a comprehensive understanding of the epigenetic regulator roles in seed development in castor bean and other important crops.

Dryopteris sect. Diclisodon is a small section of ferns with about 12 species mainly distributed in East Asia. Here, we carried out morphological and phylogenetic analyses of this section. A new species from southwest China, D. gaoligongensis, is described and illustrated. Dryopteris gaoligongensis resembles D. indonesiana and D. sparsa, but differs by having a creeping rhizome and large 4-pinnate fronds. We also show that D. glabrior Ching & Z.Y. Liu is a distinct species; however, because it is a later homonym of D. glabrior Copel., it should be renamed D. renchangiana. We conclude that a species previously known as D. nitidula, also an illegitimate homonym, should be recognized with a new name, D. sinonepalensis. We resolve the phylogenetic position of D. yoroii as sister to other sampled species of D. sect. Diclisodon. Our phylogenetic analyses confirm the distinctiveness of D. gaoligongensis, D. renchangiana, and D. sinonepalensis. A key to species of D. sect. Diclisodon in China is provided.

Two new species of Yushania (Poaceae, Bambusoideae, Arundinarieae) are described and illustrated from Hunan, China. Yushania longshanensis D.Z. Li & X.Y. Ye is distinguished from related species (Y. confusa, Y. angustifolia and Y. pachyclada) by having a thinner culm (0.2–0.3 cm in diameter), glabrous sheath scar, no oral setae, a large glabrous leaf blade (10–20 × 0.9–1.3 cm) and 3–4 pairs of secondary veins. Yushania stoloniforma D.Z. Li & X.Y. Ye has a distinctive scrambling habit, which differs from its putative close allies. Both of these two new species have a solitary branch at the basal nodes and can be assigned to Yushania sect. Yushania based on morphological features. Additionally, we treated Yushania gigantea T.P. Yi & L. Yang as a new synonym of Y. elevata T.P. Yi and renamed Y. microphylla T.P. Yi & L. Yang as Y. weiningensis D.Z. Li & X.Y. Ye.

Abstract Background Flowering plants (angiosperms) are dominant components of global terrestrial ecosystems, but phylogenetic relationships at the familial level and above remain only partially resolved, greatly impeding our full understanding of their evolution and early diversification. The plastome, typically mapped as a circular genome, has been the most important molecular data source for plant phylogeny reconstruction for decades. Results Here, we assembled by far the largest plastid dataset of angiosperms, composed of 80 genes from 4792 plastomes of 4660 species in 2024 genera representing all currently recognized families. Our phylogenetic tree (PPA II) is essentially congruent with those of previous plastid phylogenomic analyses but generally provides greater clade support. In the PPA II tree, 75% of nodes at or above the ordinal level and 78% at or above the familial level were resolved with high bootstrap support (BP ≥ 90). We obtained strong support for many interordinal and interfamilial relationships that were poorly resolved previously within the core eudicots, such as Dilleniales, Saxifragales, and Vitales being resolved as successive sisters to the remaining rosids, and Santalales, Berberidopsidales, and Caryophyllales as successive sisters to the asterids. However, the placement of magnoliids, although resolved as sister to all other Mesangiospermae, is not well supported and disagrees with topologies inferred from nuclear data. Relationships among the five major clades of Mesangiospermae remain intractable despite increased sampling, probably due to an ancient rapid radiation. Conclusions We provide the most comprehensive dataset of plastomes to date and a well-resolved phylogenetic tree, which together provide a strong foundation for future evolutionary studies of flowering plants.

Abstract The evolution of subtropical evergreen broadleaved forests (EBLFs) in East Asia is interesting while complicated. Genus‐level phylogenies indicate that the origins of EBLFs could trace back to the Oligocene–Miocene boundary or even the Eocene, while population‐level phylogeographic evidence suggests that they diversified after the Miocene, particularly in the Pleistocene. Here, we review the origins of dominant plant species to better understand the evolution of EBLFs. We compiled published estimates of the timing of origin of dominant species and diversification of evergreen relict genera from East Asian EBLFs. We also traced and visualized the evolution of EBLFs in the region using dated phylogenies and geographic distributions of the reviewed taxa. Most (76.1%) of the dominant species originated after the late Miocene, ca. 8 million years ago. Of the 10 evergreen relict genera, eight diverged near the late Miocene–Pliocene boundary or during the late Pliocene, and the remaining two diverged during the Pleistocene. Over the past 8 million years, geo‐climatic changes have triggered origins of most of the dominant EBLF species and provided refugia for evergreen relict genera. Three pulsed phases of evolution are suggested by genetic studies at the genus, species, and population levels. Fossil evidence and spatiotemporal investigations should be integrated to fully understand the evolution of EBLFs in East Asia.

IntroductionEast Asia (EA), which falls within the region of the Asian monsoon that is composed of the East Asia monsoon (EAM) and the Indian monsoon (IM), is known for its high species diversity and endemism. This has been attributed to extreme physiographical heterogeneity in conjunction with climate and sea-level changes during the Pleistocene, this hypothesis has been widely proven by phylogeographic studies. Recently, dated phylogenies have indicated that the origins (stem age) of the flora occurred after the Oligocene–Miocene boundary and are related to the establishment of the EAM.MethodsHence, this study further examined whether the strengthening of the monsoons triggered floral evolution via a meta-analysis of the tempo-spatial pattern of evolutionary radiation dates (crown ages) of 101 endemic seed plant genera.ResultsTaxonomic diversification began during the late Eocene, whereas the accumulated number of diversifications did not significantly accelerate until the late Miocene. The distribution of the weighted mean and the average divergence times in the EAM, IM, or transitional regions all fall within the mid-late Miocene. Fossils of the Tertiary relict genera are mostly and widely distributed outside EA and only half of the earliest fossils in the EA region are not older than Miocene, while their divergence times are mostly after the late Miocene. The pattern of divergence time of monotypic and polytypic taxa suggest the climatic changes after the late Pliocene exert more influence on monotypic taxa.DiscussionThe two key stages of floral evolution coincide with the intensifications of the EAM and IM, especially the summer monsoon which brings a humid climate. An integrated review of previous studies concerning flora, genus, and species levels further supports our suggestion that monsoon intensification in EA triggered the evolution of its flora.

Identification of the evolution history and genetic diversity of a species is important in the utilization of novel genetic variation in this species, as well as for its conservation. Pistacia chinensis is an important biodiesel tree crop in China, due to the high oil content of its fruit. The aim of this study was to uncover the genetic structure of P. chinensis and to investigate the influence of intraspecific gene flow on the process of domestication and the diversification of varieties. We investigated the genetic structure of P. chinensis, as well as evolution and introgression in the subpopulations, through analysis of the plastid and nuclear genomes of 39 P. chinensis individuals from across China. High levels of variation were detected in the P. chinensis plastome, and 460 intraspecific polymorphic sites, 104 indels and three small inversions were identified. Phylogenetic analysis and population structure using the plastome dataset supported five clades of P. chinensis. Population structure analysis based on the nuclear SNPs showed two groups, clearly clustered together, and more than a third of the total individuals were classified as hybrids. Discordance between the plastid and nuclear genomes suggested that hybridization events may have occurred between highly divergent samples in the P. chinensis subclades. Most of the species in the P. chinensis subclade diverged between the late Miocene and the mid-Pliocene. The processes of domestication and cultivation have decreased the genetic diversity of P. chinensis. The extensive variability and structuring of the P. chinensis plastid together with the nuclear genomic variation detected in this study suggests that much unexploited genetic diversity is available for improvement in this recently domesticated species.

Quercus variabilis (Fagaceae) is an ecologically and economically important deciduous broadleaved tree species native to and widespread in East Asia. It is a valuable woody species and an indicator of local forest health, and occupies a dominant position in forest ecosystems in East Asia. However, genomic resources from Q. variabilis are still lacking. Here, we present a high-quality Q. variabilis genome generated by PacBio HiFi and Hi-C sequencing. The assembled genome size is 787 Mb, with a contig N50 of 26.04 Mb and scaffold N50 of 64.86 Mb, comprising 12 pseudo-chromosomes. The repetitive sequences constitute 67.6% of the genome, of which the majority are long terminal repeats, accounting for 46.62% of the genome. We used ab initio, RNA sequence-based and homology-based predictions to identify protein-coding genes. A total of 32,466 protein-coding genes were identified, of which 95.11% could be functionally annotated. Evolutionary analysis showed that Q. variabilis was more closely related to Q. suber than to Q. lobata or Q. robur. We found no evidence for species-specific whole genome duplications in Quercus after the species had diverged. This study provides the first genome assembly and the first gene annotation data for Q. variabilis. These resources will inform the design of further breeding strategies, and will be valuable in the study of genome editing and comparative genomics in oak species.

Abstract Mountain ecosystems support a significant one‐third of all terrestrial biodiversity, but our understanding of the spatiotemporal maintenance of this high biodiversity remains poor, or at best controversial. The Himalaya hosts a complex mountain ecosystem with high topographic and climatic heterogeneity and harbors one of the world's richest floras. The high species endemism, together with increasing anthropogenic threats, has qualified the Himalaya as one of the most significant global biodiversity hotspots. The topographic and climatic complexity of the Himalaya makes it an ideal natural laboratory for studying the mechanisms of floral exchange, diversification, and spatiotemporal distributions. Here, we review literature pertaining to the Himalaya in order to generate a concise synthesis of the origin, distribution, and climate change responses of the Himalayan flora. We found that the Himalaya supports a rich biodiversity and that the Hengduan Mountains supplied the majority of the Himalayan floral elements, which subsequently diversified from the late Miocene onward, to create today's relatively high endemicity in the Himalaya. Further, we uncover links between this Miocene diversification and the joint effect of geological and climatic upheavals in the Himalaya. There is marked variance regarding species dispersal, elevational gradients, and impact of climate change among plant species in the Himalaya, and our review highlights some of the general trends and recent advances on these aspects. Finally, we provide some recommendations for conservation planning and future research. Our work could be useful in guiding future research in this important ecosystem and will also provide new insights into the maintenance mechanisms underpinning other mountain systems.

Abstract Background Castor bean (Ricinus communis L.) is an important oil crop, which belongs to the Euphorbiaceae family. The seed oil of castor bean is currently the only commercial source of ricinoleic acid that can be used for producing about 2000 industrial products. However, it remains largely unknown regarding the origin, domestication, and the genetic basis of key traits of castor bean. Results Here we perform a de novo chromosome-level genome assembly of the wild progenitor of castor bean. By resequencing and analyzing 505 worldwide accessions, we reveal that the accessions from East Africa are the extant wild progenitors of castor bean, and the domestication occurs ~ 3200 years ago. We demonstrate that significant genetic differentiation between wild populations in Kenya and Ethiopia is associated with past climate fluctuation in the Turkana depression ~ 7000 years ago. This dramatic change in climate may have caused the genetic bottleneck in wild castor bean populations. By a genome-wide association study, combined with quantitative trait locus analysis, we identify important candidate genes associated with plant architecture and seed size. Conclusions This study provides novel insights of domestication and genome evolution of castor bean, which facilitates genomics-based breeding of this important oilseed crop and potentially other tree-like crops in future.

Abstract Background The Rhododendron sanguineum complex is endemic to alpine mountains of northwest Yunnan and southeast Tibet of China. Varieties in this complex exhibit distinct flower colors even at the bud stage. However, the underlying molecular regulations for the flower color variation have not been well characterized. Here, we investigated this via measuring flower reflectance profiles and comparative transcriptome analyses on three coexisting varieties of the R. sanguineum complex, with yellow flush pink, bright crimson, and deep blackish crimson flowers respectively. We compared the expression levels of differentially-expressed-genes (DEGs) of the anthocyanin / flavonoid biosynthesis pathway using RNA-seq and qRT-PCR data. We performed clustering analysis based on transcriptome-derived Single Nucleotide Polymorphisms (SNPs) data, and finally analyzed the promoter architecture of DEGs. Results Reflectance spectra of the three color morphs varied distinctively in the range between 400 and 700 nm, with distinct differences in saturation, brightness, hue, and saturation/hue ratio, an indirect measurement of anthocyanin content. We identified 15,164 orthogroups that were shared among the three varieties. The SNP clustering analysis indicated that the varieties were not monophyletic. A total of 40 paralogous genes encoding 12 enzymes contributed to the flower color polymorphism. These anthocyanin biosynthesis-related genes were associated with synthesis, modification and transportation properties (RsCHS, RsCHI, RsF3H, RsF3′H, RsFLS, RsANS, RsAT, RsOMT, RsGST), as well as genes involved in catabolism and degradation (RsBGLU, RsPER, RsCAD). Variations in sequence and cis-acting elements of these genes might correlate with the anthocyanin accumulation, thus may contribute to the divergence of flower color in the R. sanguineum complex. Conclusions Our results suggested that the varieties are very closely related and flower color variations in the R. sanguineum complex correlate tightly with the differential expression levels of genes involved in the anabolic and catabolic synthesis network of anthocyanin. Our study provides a scenario involving intricate relationships between genetic mechanisms for floral coloration accompanied by gene flow among the varieties that may represent an early case of pollinator-mediated incipient sympatric speciation.

Salvia is the largest genus of Lamiaceae, with almost 1000 species, and has been divided into 11 subgenera. Salvia subg. Glutinaria, native to East Asia, is particularly important because of its potential medicinal value. However, the interspecific relationships of this subgenus have not been resolved and the plastomes of Salvia have rarely been studied. In the current study, we compared plastid genome structure and organization of 19 species of Salvia (14 newly sequenced and 5 previously published). Our comparative analysis showed that all Salvia plastomes examined have a quadripartite structure typical of most angiosperms and contain an identical set of 114 unique genes (80 protein-coding genes, 4 rRNA genes, and 30 tRNA genes). The plastome structure of all Salvia species is highly conserved like other Lamiaceae plastomes. Gene content, gene order, and GC content were highly similar in these plastomes. The inverted repeats/single copy region (IR/SC) boundaries of Salvia are highly conserved, and IR contraction only occurred in two species (Salvia mekongensis and S. rosmarinus). In Salvia, sequence divergence was higher in non-coding regions than in coding regions. We found that using large single copy (LSC) and small single copy regions (SSC) with exclusion of the rapidly evolving sites produced the highest resolution in phylogenetic analysis of Salvia, suggesting that using suitable informative sites to build trees is more conducive in phylogenetic research. This study assembled a powerful matrix data set for studying the phylogeny of Salvia, resolving the interspecific relationship of Salvia subg. Glutinaria. The newly sequenced plastid genomes will also enrich the plastome database of Salvia, providing the scientific basis for the development and utilization of germplasm resources of this large and important genus.

Nervonic acid (NA, cis-15-tetracosenoic acid) is a very long-chain monounsaturated fatty acid that has been shown to be a core component of nerve fibers and nerve cells. It can be used to treat and prevent many neurological diseases. At present, commercially available NA is mainly derived from Acer truncatum seeds, which contain about 5%–6% NA in their seed oil. The aim of this study were to identify and analyze NA-containing Acer species that could be used as NA resource plants. For this purpose, 46 Acer species seeds were collected in China and in some or all of the seed oils from these species 15 fatty acids were detected, including linoleic acid, oleic acid (C18:1Δ9, C18:1Δ11), erucic acid, palmitic acid, NA, linolenic acid (C18:3Δ6,9,12, C18:3Δ9,12,15), eicosenoic acid (C20:1Δ11, C20:1Δ13), stearic acid, behenic acid, tetracosanoic acid, arachidic acid, and docosadienoic acid. Nervonic acid was detected in all samples, but the content was highly variable among species. NA content over 9% was detected in eleven species, of which Acer elegantulum had the highest levels (13.90%). The seed oil content, seed weight, and fatty acid profiles varied among species, but the comprehensive evaluation value (W) showed that A. coriaceifolium could be a new potential NA resources plant. The results also showed that NA was significantly negatively correlated with palmitic acid, oleic acid, and eicosenoic acid, but positively correlated with eicosadienoic acid, behenic acid, erucic acid, and tetracosanoic acid, which indicate the probable pathway for NA biosynthesis in Acer plants. This study has identified Acer species that may serve as NA resources and will help guide subsequent species breeding programs.

Abstract In East Asia, genetic divergence is usually considered to be correlated to different floristic regions, however, subtropical-tropical divergence is largely ignored, compared to widely explored temperate-subtropical divergence. Lindera aggregata (Lauraceae), a dominant species in South-East China was selected to address this issue. Fifteen low-copy nuclear genes (LCGs) and four chloroplast DNA (cpDNA) fragments were used to detect its evolutionary history. In LCGs, STRUCTURE and dated Bayesian phylogeny analyses detect distinct subtropical-tropical divergence since late Pleistocene. Approximate Bayesian calculation (ABC) further supports the distinct subtropical-tropical divergence, and close related Taiwan and South China populations are diverged at the last interglacial. Isolation by distance, isolation by environment and isolation by resistance analyses suggest the current climatic difference rather than geographical distance contributes to the genetic differentiation. Principle component analysis shows populations of tropical cluster occur in warmer area with higher precipitation. Ancestral area reconstruction based on Bayesian phylogeny indicates that ancestral L. aggregata populations are distributed in tropical region. In cpDNA, although unique haplotypes are found in tropical region, distinct subtropical-tropical divergence is absent. In conclusion, distinct late Pleistocene subtropical-tropical divergence of L. aggregata is triggered by climate. It is likely that L. aggregata is originated in Southwest-South China and experienced hierarchical dispersal from south to north. The South China Sea land bridge has dual role in connecting or isolating Taiwan and mainland populations since the last glaciation.

Gigantochloa glabrata N. H. Xia & Y. Zeng ex D. Z. Li & Z. C. Xu, sp. nov., a new species of paleotropical woody bamboo has been described and illustrated from Yunnan, China. The new species is morphologically similar to G. albociliata and G. levis, but differs from them by having erect culm sheath blades; culm sheath ligules 4–6 mm high, truncate, denticulate; and with a ring of white tomentum on the intranode and below the node. The new species was mistakenly identified as Gigantochloa albociliata in the Flora of China and was recognised with description of the vegetative characters in 2014, but it was not effectively published. Here, we designate a complete specimen with inflorescence as the type and describe it in accordance with the Code.

Two new species of Fargesia, one from Xizang (Tibet) and one from Yunnan, China, are described and illustrated. Fargesia viridis D.Z. Li & X.Y. Ye is characterized by its densely white powder, nearly solid internodes, yellow setose sheath scar and culm sheaths, and 4–6 leaves of large size. Fargesia purpurea D.Z. Li & X.Y. Ye has thinner culms (0.5–1.4 cm in diameter), a ring of 4–5 mm tall brown setae below nodes, fewer branches, glabrous sheath scar and culm sheaths, differentiated from the related species.

Species of Cephalotaxus have great economic and ecological values. However, the taxonomy and interspecific phylogenetic relationships within the genus have been controversial and remained not fully resolved until now. To date, no study examined the efficiency of the complete plastome as super-barcode across Cephalotaxus species with multiple samples per taxon. In this study, we have evaluated the complete plastome in species discrimination and phylogenetic resolution in Cephalotaxus by including 32 individuals of all eight recognized species and five varieties following Farjon’s classification (2010) with multiple samples per taxon. Our results indicated that not all species recognized in recent taxonomic revisions of Cephalotaxus could be distinguished and not all were monophyletic. Based on the plastome phylogeny, a new taxonomic classification for the genus comprising nine species and two varieties, including a cryptic species, was proposed. The phylogeny also resolved all interspecific relationships. Compared to the plastome based classification, standard DNA barcodes, alone or in combination, only recognized a maximum of seven out of the nine species. Moreover, two highly variable single loci, ycf1 and rps16, each alone achieved full species discrimination. With the moderate length of 1079 bp, rps16 is proposed as a specific barcode to discriminate Cephalotaxus species. The super-barcodes and specific barcode candidates will aid in the identification of endangered Cephalotaxus species, and to help focus conservation measures.

Structural variation of plastid genomes (plastomes), particularly large inversions and gene losses, can provide key evidence for the deep phylogeny of plants. In this study, we investigated the structural variation of fern plastomes in a phylogenetic context. A total of 127 plastomes representing all 50 recognized families and 11 orders of ferns were sampled, making it the most comprehensive plastomic analysis of fern lineages to date. The samples included 42 novel plastomes of 15 families with a focus on Hymenophyllales and Gleicheniales. We reconstructed a well-supported phylogeny of all extant fern families, detected significant structural synapomorphies, including 9 large inversions, 7 invert repeat region (IR) boundary shifts, 10 protein-coding gene losses, 7 tRNA gene losses or anticodon changes, and 19 codon indels (insertions or deletions) across the deep phylogeny of ferns, particularly on the backbone nodes. The newly identified inversion V5, together with the newly inferred expansion of the IR boundary R5, can be identified as a synapomorphy of a clade composed of Dipteridaceae, Matoniaceae, Schizaeales, and the core leptosporangiates, while a unique inversion V4, together with an expansion of the IR boundary R4, was verified as a synapomorphy of Gleicheniaceae. This structural evidence is in support of our phylogenetic inference, thus providing key insight into the paraphyly of Gleicheniales. The inversions of V5 and V7 together filled the crucial gap regarding how the “reversed” gene orientation in the IR region characterized by most extant ferns (Schizaeales and the core leptosporangiates) evolved from the inferred ancestral type as retained in Equisetales and Osmundales. The tRNA genes trnR-ACG and trnM-CAU were assumed to be relicts of the early-divergent fern lineages but intact in most Polypodiales, particularly in eupolypods; and the loss of the tRNA genes trnR-CCG, trnV-UAC, and trnR-UCU in fern plastomes was much more prevalent than previously thought. We also identified several codon indels in protein-coding genes within the core leptosporangiates, which may be identified as synapomorphies of specific families or higher ranks. This study provides an empirical case of integrating structural and sequence information of plastomes to resolve deep phylogeny of plants.

Urticeae s.l., a tribe of Urticaceae well-known for their stinging trichomes, consists of more than 10 genera and approximately 220 species. Relationships within this tribe remain poorly known due to the limited molecular and taxonomic sampling in previous studies, and chloroplast genome (CP genome/plastome) evolution is still largely unaddressed. To address these concerns, we used genome skimming data—CP genome and nuclear ribosomal DNA (18S-ITS1-5.8S-ITS2-26S); 106 accessions—for the very first time to attempt resolving the recalcitrant relationships and to explore chloroplast structural evolution across the group. Furthermore, we assembled a taxon rich two-locus dataset of trnL-F spacer and ITS sequences across 291 accessions to complement our genome skimming dataset. We found that Urticeae plastomes exhibit the tetrad structure typical of angiosperms, with sizes ranging from 145 to 161 kb and encoding a set of 110–112 unique genes. The studied plastomes have also undergone several structural variations, including inverted repeat (IR) expansions and contractions, inversion of the trnN-GUU gene, losses of the rps19 gene, and the rpl2 intron, and the proliferation of multiple repeat types; 11 hypervariable regions were also identified. Our phylogenomic analyses largely resolved major relationships across tribe Urticeae, supporting the monophyly of the tribe and most of its genera except for Laportea, Urera, and Urtica, which were recovered as polyphyletic with strong support. Our analyses also resolved with strong support several previously contentious branches: (1) Girardinia as a sister to the Dendrocnide-Discocnide-Laportea-Nanocnide-Zhengyia-Urtica-Hesperocnide clade and (2) Poikilospermum as sister to the recently transcribed Urera sensu stricto. Analyses of the taxon-rich, two-locus dataset showed lower support but was largely congruent with results from the CP genome and nuclear ribosomal DNA dataset. Collectively, our study highlights the power of genome skimming data to ameliorate phylogenetic resolution and provides new insights into phylogenetic relationships and chloroplast structural evolution in Urticeae.

Intra-specific genetic diversity is a fundamental component of biodiversity, and is key to species adaptation and persistence. However, significant knowledge gaps still exist in our understanding of the patterns of genetic diversity and their key determinants. Most previous investigations mainly utilized single-species and/or a limited number of explanatory variables; so here we mapped the patterns of plastid genetic diversity within 15 plant species, and explored the key determinants shaping these patterns using a wide range of variables. Population-level cpDNA sequence data for 15 plant species from the Longitudinal Range Gorge Region (LRGR), southwest China, were retrieved from literature and used to estimate haplotype diversity (HD) and population pairwise genetic differentiation (FST) indices. Genetic diversity and divergence landscape surfaces were then generated based on the HD and FST, respectively, to clarify the patterns of genetic structure in the region. Subsequently, we analyzed the relationships between plastid genetic diversity and 16 explanatory variables (classified as anthropogenic, climatic, and topographic). We found that the highest genetic diversity occurred in the Yulong Mountain region, with a significant proportion (~74.81%) of the high diversity land area being located outside of protected areas. The highest genetic divergence was observed approximately along the 25°N latitudinal line, with notable peaks in the western and eastern edges of the LRGR. Genetic diversity (HD) was weakly but significantly positively correlated with both Latitude (lat) and Annual Mean Wet Day Frequency (wet), yet significantly negatively correlated with all of Longitude (long), Annual Mean Cloud Cover Percent (cld), Annual Mean Anthropogenic Flux (ahf), and Human Footprint Index (hfp). A combination of climatic, topographic, and anthropogenic factors explained a significant proportion (78%) of genetic variation, with topographic factors (lat and long) being the best predictors. Our analysis identified areas of high genetic diversity (genetic diversity “hotspots”) and divergence in the region, and these should be prioritized for conservation. This study contributes to a better understanding of the features that shape the distribution of plastid genetic diversity in the LRGR and thus would inform conservation management efforts in this species-rich, but vulnerable region.

Morphological approaches often fail to delimit species in recently derived species complexes. This can be exacerbated in historical collections which may have lost key features in specimen preparation and preservation. Here, we examine the Pedicularis siphonantha complex, endemic to the Mountains of Southwest China. This complex is characterized by its red/purple/pink and long-tubular corolla, and twisted, beaked galea. However, herbarium specimens are often difficult to identify to species. Molecular approaches using nrITS or nuclear ribosomal internal transcribed spacer (nrITS) + plastid DNA (ptDNA) have been successfully used for species identification in Pedicularis. To resolve taxonomic confusion in the Pedicularis siphonantha complex, we reconstructed phylogenies of the complex using nrITS and four plastid DNA loci (matK, rbcL, trnH-psbA, and trnL-F). To recover as much of the phylogenetic history as possible, we sampled individuals at the population level. Topological incongruence between the nrITS and ptDNA datasets was recovered in clades including two widely distributed species, Pedicularis milliana and Pedicularis tenuituba. Based on morphological, geographical, and genetic evidence, we suggest that hybridization/introgression has occurred between P. milliana and Pedicularis sigmoidea/Pedicularis sp. 1 in the Yulong Snow Mountain of Lijiang, northwest Yunnan, and between P. tenuituba and Pedicularis leptosiphon in Ninglang, northwest Yunnan. After removing conflicting DNA regions in Pedicularis dolichosiphon (nrITS) and P. milliana (ptDNA), the concatenated nrITS and ptDNA phylogenies distinguish 11 species in the P. siphonantha complex, including two undescribed species, from the Jiaozi and Yulong Snow Mountains, respectively. Phylogeographical analyses indicate that the P. siponantha complex originated from south of the Hengduan Mountains, expanding north to the Himalayas and the Yunnan-Guizhou Plateau. Moreover, the uplift of the Qinghai-Tibet Plateau and climate oscillations may have driven further diversification in the complex.

Cytidine-to-uridine (C-to-U) RNA editing is common in coding regions of organellar genomes throughout land plants. In most cases RNA editing alters translated amino acids or creates new start codons, potentially confounds phylogenetic reconstructions. In this study, we used the spike moss genus Selaginella (lycophytes), which has the highest frequency of RNA editing, as a model to test the effects of extreme RNA editing on phylogenetic reconstruction. We predicted the C-to-U RNA editing sites in coding regions of 18 Selaginella plastomes, and reconstructed the phylogenetic relationships within Selaginella based on three data set pairs consisted of plastome or RNA-edited coding sequences, first and second codon positions, and translated amino acid sequences, respectively. We predicted between 400 and 3100 RNA editing sites of 18 Selaginella plastomes. The numbers of RNA editing sites in plastomes were highly correlated with the GC content of first and second codon positions, but not correlated with the GC content of plastomes as a whole. Contrast phylogenetic analyses showed that there were substantial differences (e.g., the placement of clade B in Selaginella) between the phylogenies generated by the plastome and RNA-edited data sets. This empirical study provides evidence that extreme C-to-U RNA editing in the coding regions of organellar genomes alters the sequences used for phylogenetic reconstruction, and might even confound phylogenetic reconstruction. Therefore, RNA editing sites should be corrected when plastid or mitochondrial genes are used for phylogenetic studies, particularly in those lineages with abundant organellar RNA editing sites, such as hornworts, quillworts, spike mosses, and some seed plants.

Abstract GetOrganelle is a state-of-the-art toolkit to accurately assemble organelle genomes from whole genome sequencing data. It recruits organelle-associated reads using a modified “baiting and iterative mapping” approach, conducts de novo assembly, filters and disentangles the assembly graph, and produces all possible configurations of circular organelle genomes. For 50 published plant datasets, we are able to reassemble the circular plastomes from 47 datasets using GetOrganelle. GetOrganelle assemblies are more accurate than published and/or NOVOPlasty-reassembled plastomes as assessed by mapping. We also assemble complete mitochondrial genomes using GetOrganelle. GetOrganelle is freely released under a GPL-3 license ( https://github.com/Kinggerm/GetOrganelle ).

Lush jungle flagship species, woody bamboos (Poaceae–Bambusoideae) are famed for their synchronous flowering as well as the extensive “bamboo forests” some species can form in tropical or temperate environments. In portions of their natural distribution, Bambusoideae members developed various adaptations to seasonality in environmental parameters, such as frost or seasonal drought. A new taxon, Laobambos calcareus, described here, is extremely novel in showing the first documented case of succulence in bamboos, with its ability to seasonally vary the volume of its stem depending on the quantity of water stored. Anatomical studies presented in this paper document this specificity at the cellular level. Though no flowers or fruits are known yet, unique morphological characteristics along with an investigation of its phylogenetic affinities using molecular data show that this new taxon should belong to a new genus herein described.

The Poales is one of the largest orders of flowering plants with significant economic and ecological values. Reconstructing the phylogeny of the Poales is important for understanding its evolutionary history that forms the basis for biological studies. However, due to sparse taxon sampling and limited molecular data, previous studies have resulted in a variety of contradictory topologies. In particular, there are three nodes surrounded by incongruence: the phylogenetic ambiguity near the root of the Poales tree, the sister family of Poaceae, and the delimitation of the xyrid clade. We conducted a comprehensive sampling and reconstructed the phylogenetic tree using plastid and mitochondrial genomic data from 91 to 66 taxa, respectively, representing all the 16 families of Poales. Our analyses support the finding of Bromeliaceae and Typhaceae as the earliest diverging groups within the Poales while having phylogenetic relationships with the polytomy. The clade of Ecdeiocoleaceae and Joinvilleaceae is recovered as the sister group of Poaceae. The three families, Mayacaceae, Eriocaulaceae, and Xyridaceae, of the xyrid assembly diverged successively along the backbone of the Poales phylogeny, and thus this assembly is paraphyletic. Surprisingly, we find substantial phylogenetic conflicts within the plastid genomes of the Poales, as well as among the plastid, mitochondrial, and nuclear data. These conflicts suggest that the Poales could have a complicated evolutionary history, such as rapid radiation and polyploidy, particularly allopolyploidy through hybridization. In sum, our study presents a new perspicacity into the complex phylogenetic relationships and the underlying phylogenetic conflicts within the Poales.

Shibataea is a genus of temperate bamboos (Poaceae: Bambusoideae) endemic to China, but little is known about its phylogenetic position and interspecific relationships. To elucidate the phylogenetic relationship of the bamboo genus Shibataea, we performed genome-scale phylogenetic analysis of all seven species and one variety of the genus using double digest restriction-site associated DNA sequencing (ddRAD-seq) and whole plastid genomes generated using genome skimming. Our phylogenomic analyses based on ddRAD-seq and plastome data congruently recovered Shibataea as monophyletic. The nuclear data resolved S. hispida as the earliest diverged species, followed by S. chinensis, while the rest of Shibataea can be further divided into two clades. However, the plastid and nuclear topologies conflict significantly. By comparing the results of network analysis and topologies reconstructed from different datasets, we identify S. kumasasa as the most admixed species, which may be caused by incomplete lineage sorting (ILS) or interspecific gene flow with four sympatric species. This study highlights the power of ddRAD and plastome data in resolving complex relationships in the intractable bamboo genus. Keywords: Shibataea, ddRAD-seq, Genome skimming, Phylogeny, Incongruence

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Dendrocalamus menghanensis P.Y.Wang & D.Z.Li, a new species of woody bamboos endemic to south Yunnan, China, is described and illustrated. The new species is morphologically similar to D. semiscandens and D. birmanicus but differs in having a reflexed culm sheath blade, 10 mm high culm sheath ligule, 1 mm high leaf sheath ligule, 4 florets and 1 glume.

Bulbophyllum reflexipetalum, a new species from Motuo County, Southeast Xizang, China, is described and illustrated here. This new species belongs to Bulbophyllum sect. Umbellata Bentham & J. D. Hooker, and it is morphologically similar to B. umbellatum Lindley, B. guttulatum (J. D. Hooker) N. P. Balakrishnan and B. salweenensis X.H. Jin, but is distinguished from them by having reflexed petals, base of dorsal sepal with 1 dentate on each side, lip with significantly revolute margin, adaxially with dark brown spots or patches and one longitudinal groove.

Marsdenia yarlungzangboensis (Apocynaceae, Asclepiadoideae), a new species from Motuo County, southeastern Xizang of China, is described and illustrated. It is morphologically similar to M. medogensis, M. tenii and M. yuei, the major differences between the new species and the morphological relatives are outlined and discussed. A diagnostic key to the new species and its closely related species in China is provided.

Pedicularis multicaulis W.B.Yu, H.Wang & D.Z.Li (series Oliganthae Prain) is a new species described and illustrated herein. This new species is endemic to northwest Yunnan and only two populations were found in Weixi county. Phylogenetic analyses support P. multicaulis as a new species, sister to P. taihaiensis Bonati and P. macilenta Franch. Morphological comparisons between P. multicaulis and P. macilenta and P. taihaiensis also support P. multicaulis as a new species to science.

Yushania tongpeii D.Z.Li, Y.X.Zhang & E.D.Liu, a new species of the temperate bamboo tribe Arundinarieae (Poaceae: Bambusoideae), is described and illustrated from north-eastern Yunnan, China. Yushania tongpeii is characterised by taller branching from nodes 1–2 m above the ground, usually three branches at the node, sparse purple spots and thin white powder on the internode, densely purple-spotted culm sheaths, glabrous margins of culm sheaths and tomentose leaf ligules. Based on the morphological features, this new species is assigned to section Yushania.