Plant Diversity最新文献

Dryopteridaceae are the largest fern family and include nearly 20% of extant fern diversity, with 24 currently recognized genera. Recognition and delineation of genera within this family have varied greatly. The three-subfamily classification of Dryopteridaceae was based primarily on molecular phylogenetic relationships but lacked morphological evidence, and the phylogenetic relationships of the subfamilies and genera of Dryopteridaceae are only partially resolved. A comprehensive and robust phylogeny is urgently needed. The heterogeneous morphology of the current members of Dryopteridaceae makes the family and its subfamilies difficult to define by single morphological characteristics or even character combinations. We carried out phylogenetic analyses to reconstruct a highly supported phylogeny of Dryopteridaceae. Our analyses recovered 24 strongly supported clades grouped into seven major clades of Dryopteridaceae. Seven morphological characters including habit, rhizome shape, frond morphology, rachis-costae architecture, appendages on stipe base and lamina, and soral arrangement were found to be informative for identifying different major clades and clades in Dryopteridaceae. Based on phylogenetic reconstruction and morphological analysis, we presented an updated infra-familial classification of Dryopteridaceae with seven subfamilies and 24 genera including four newly proposed subfamilies (Ctenitidoideae, Lastreopsidoideae, Pleocnemioideae, and Polystichopsidoideae). Morphological character combinations of each subfamily are summarized, and a key is provided. Most genera sensu PPG I are recognized, with Stigmatopetris reclassified into Dryopteridoideae and Arthrobotrya considered a synonym of Teratophyllum. A new genus Pseudarachniodes is introduced. This revised classification will serve as a foundational framework for future investigations on taxonomy, biogeography, and diversification of the most species-rich Dryopteridaceae in ferns.

Genome skimming has dramatically extended DNA barcoding from short DNA fragments to next generation barcodes in plants. However, conserved DNA barcoding markers, including complete plastid genome and nuclear ribosomal DNA (nrDNA) sequences, are inadequate for accurate species identification. Skmer, a recently proposed approach that estimates genetic distances among species based on unassembled genome skims, has been proposed to effectively improve species discrimination rate. In this study, we used Skmer to identify species based on genomic skims of 47 individuals representing 10 out of 13 species of Schima (Theaceae) from China. The unassembled reads identified six species, with a species identification rate of 60%, twice as high as previous efforts that used plastid genomes (27.27%). In addition, Skmer was able to identify Schima species with only 0.5× sequencing depth, as six species were well-supported with unassembled data sizes as small as 0.5 Gb. These findings demonstrate the potential for Skmer approach in species identification, where nuclear genomic data plays a crucial role. For taxonomically difficult taxa such as Schima, which have diverged recently and have low levels of genetic variation, Skmer is a promising alternative to next generation barcodes.

The common walnut (Juglans regia) is one of the most economically important nut trees cultivated worldwide. Despite its importance, no comprehensive evaluation of walnut tree population genetics has been undertaken across the range where it originated, Central Asia. In this study, we investigated the genetic diversity and population structure of 1082 individuals from 46 populations across Central Asia. We found moderate genetic diversity of J. regia across Central Asia, with 46 populations clustered into three groups with a weak relationship between genetic and geographic distance. Our findings reveal that the western Himalaya might be the core region of common walnut genetic diversity in Central Asia and that, except for two populations in Gongliu Wild Walnut Valley, humans might have introduced walnut populations to Xinjiang, China. The observed distribution of the genetic landscape has probably been affected by historical climate fluctuation, breeding system, and prolonged anthropogenic activity. We propose the conservation of the core genetic diversity resources in the western Himalaya and pay special attention to populations from Gongliu in Xinjiang. These findings enhance our understanding of the genetic variation throughout the distribution range of J. regia in Central Asia, which will provide a key prerequisite for evidence-based conservation and management.

The timing of flowering is an important driver of species distribution and community assembly patterns. However, we still have much to learn about the factors that shape flowering diversity (i.e., number of species flowering per period) in plant communities. One potential explanation of flowering diversity is the mid-domain effect, which states that geometric constraints on species ranges within a bounded domain (space or time) will yield a mid-domain peak in diversity regardless of ecological factors. Here, we determine whether the mid-domain effect explains peak flowering time (i.e., when most species of communities are flowering) across China. We used phenological data of 16,267 herbaceous and woody species from the provincial Flora in China and species distribution data from the Chinese Vascular Plant Distribution Database to determine relationships between the observed number of species flowering and the number of species flowering as predicted by the mid-domain effect model, as well as between three climatic variables (mean minimum monthly temperature, mean monthly precipitation, and mean monthly sunshine duration). We found that the mid-domain effect explained a significant proportion of the temporal variation in flowering diversity across all species in China. Further, the mid-domain effect explained a greater proportion of variance in flowering diversity at higher latitudes than at lower latitudes. The patterns of flowering diversity for both herbaceous and woody species were related to both the mid-domain effect and environmental variables. Our findings indicate that including geometric constraints in conjunction with abiotic and biotic predictors will improve predictions of flowering diversity patterns.

Phlomoides, with 150-170 species, is the second largest and perhaps most taxonomically challenging genus within the subfamily Lamioideae (Lamiaceae). With about 60 species, China is one of three major biodiversity centers of Phlomoides. Although some Phlomoides species from China have been included in previous molecular phylogenetic studies, a robust and broad phylogeny of this lineage has yet to be completed. Moreover, given the myriad new additions to the genus, the existing infrageneric classification needs to be evaluated and revised. Here, we combine molecular and morphological data to investigate relationships within Phlomoides, with a focus on Chinese species. We observed that plastid DNA sequences can resolve relationships within Phlomoides better than nuclear ribosomal internal and external transcribed spacer regions (nrITS and nrETS). Molecular phylogenetic analyses confirm the monophyly of Phlomoides, but most previously defined infrageneric groups are not monophyletic. In addition, morphological analysis demonstrates the significant taxonomic value of eight characters to the genus. Based on our molecular phylogenetic analyses and morphological data, we establish a novel section Notochaete within Phlomoides, and propose three new combinations as well as three new synonyms. This study presents the first molecular phylogenetic analyses of Phlomoides in which taxa representative of the entire genus are included, and highlights the phylogenetic and taxonomic value of several morphological characters from species of Phlomoides from China. Our study suggests that a taxonomic revision and reclassification for the entire genus is necessary in the future.

Leaf economics spectrum (LES) describes the fundamental trade-offs between leaf structural, chemical, and physiological investments. Generally, structurally robust thick leaves with high leaf dry mass per unit area (LMA) exhibit lower photosynthetic capacity per dry mass (A _mass). Paradoxically, "soft and thin-leaved" mosses and spikemosses have very low A _mass, but due to minute-size foliage elements, their LMA and its components, leaf thickness (LT) and density (LD), have not been systematically estimated. Here, we characterized LES and associated traits in cryptogams in unprecedented details, covering five evolutionarily different lineages. We found that mosses and spikemosses had the lowest LMA and LT values ever measured for terrestrial plants. Across a broad range of species from different lineages, A _mass and LD were negatively correlated. In contrast, A _mass was only related to LMA when LMA was greater than 14 g cm^{- 2}. In fact, low A _mass reflected high LD and cell wall thickness in the studied cryptogams. We conclude that evolutionarily old plant lineages attained poorly differentiated, ultrathin mesophyll by increasing LD. Across plant lineages, LD, not LMA, is the trait that represents the trade-off between leaf robustness and physiology in the LES.

Polyploidy is a major factor in the evolution of plants, yet we know little about the origin and evolution of polyploidy in intertidal species. This study aimed to identify the evolutionary transitions in three true-mangrove species of the genus Acanthus distributed in the Indo-West Pacific region. For this purpose, we took an integrative approach that combined data on morphology, cytology, climatic niche, phylogeny, and biogeography of 493 samples from 42 geographic sites. Our results show that the Acanthus ilicifolius lineage distributed east of the Thai-Malay Peninsula possesses a tetraploid karyotype, which is morphologically distinct from that of the lineage on the west side. The haplotype networks and phylogenetic trees for the chloroplast genome and eight nuclear genes reveal that the tetraploid species has two sub-genomes, one each from A. ilicifolius and A . ebracteatus, the paternal and maternal parents, respectively. Population structure analysis also supports the hybrid speciation history of the new tetraploid species. The two sub-genomes of the tetraploid species diverged from their diploid progenitors during the Pleistocene. Environmental niche models revealed that the tetraploid species not only occupied the near-entire niche space of the diploids, but also expanded into novel environments. Our findings suggest that A. ilicifolius species distributed on the east side of the Thai-Malay Peninsula should be regarded as a new species, A. tetraploideus, which originated from hybridization between A. ilicifolius and A. ebracteatus, followed by chromosome doubling. This is the first report of a true-mangrove allopolyploid species that can reproduce sexually and clonally reproduction, which explains the long-term adaptive potential of the species.

China is a hotspot of relict plant species that were once widespread throughout the Northern Hemisphere. Recent research has demonstrated that the occurrence of long-term stable refugia in the mountainous regions of central and south-western China allowed their persistence through the late Neogene climate fluctuations. One of these relict lineages is Dipteronia, an oligotypic tree genus with a fossil record extending to the Paleocene. Here, we investigated the genetic variability, demographic dynamics and diversification patterns of the two currently recognized Dipteronia species (D ipteronia sinensis and D . dyeriana). Molecular data were obtained from 45 populations of Dipteronia by genotyping three cpDNA regions, two single copy nuclear genes and 15 simple sequence repeat loci. The genetic study was combined with niche comparison analyses on the environmental space, ecological niche modeling, and landscape connectivity analysis. We found that the two Dipteronia species have highly diverged both in genetic and ecological terms. Despite the incipient speciation processes that can be observed in D. sinensis, the occurrence of long-term stable refugia and, particularly, a dispersal corridor along Daba Shan-west Qinling, likely ensured its genetic and ecological integrity to date. Our study will not only help us to understand how populations of Dipteronia species responded to the tectonic and climatic changes of the Cenozoic, but also provide insight into how Arcto-Tertiary relict plants in East Asia survived, evolved, and diversified.

•Phylogenomic analysis uncovers widespread discordance in the extended Picea likiangensis complex.•Introgression (54.99%) and incomplete lineage sorting (ILS; 33.12%) are key drivers of this incongruity.•Recombination rates shape ILS and introgression, with high rates correlating with elevated levels.•Genes linked to abiotic stress responses exhibit significant introgression and ILS, suggesting adaptive evolution.•Lower recombination rates improve accuracy in species relationships.

Vernalization is necessary for winter wheat to flower. However, it is unclear whether vernalization is also required for spring wheat, which is frequently sown in fall, and what molecular mechanisms underlie the vernalization response in wheat varieties. In this study, we examined the molecular mechanisms that regulate vernalization response in winter and spring wheat varieties. For this purpose, we determined how major vernalization genes (VRN1, VRN2, and VRN3) respond to vernalization in these varieties and whether modifications to histones play a role in changes in gene expression. We also identified genes that are differentially regulated in response to vernalization in winter and spring wheat varieties. We found that in winter wheat, but not in spring wheat, VRN1 expression decreases when returned to warm temperature following vernalization. This finding may be associated with differences between spring and winter wheat in the levels of tri-methylation of lysine 27 on histone H3 (H3K27me3) and tri-methylation of lysine 4 on histone H3 (H3K4me3) at the VRN1 gene. Analysis of winter wheat transcriptomes before and after vernalization revealed that vernalization influences the expression of several genes, including those involved in leucine catabolism, cysteine biosynthesis, and flavonoid biosynthesis. These findings provide new candidates for further study on the mechanism of vernalization regulation in wheat.