The Eastern Himalayas are renowned for their high plant diversity. To understand how this modern botanical richness formed, it is critical to investigate past plant biodiversity preserved as fossils throughout the eastern Himalayan Siwalik succession (middle Miocene-early Pleistocene). Here, we present a summary of plant diversity records that document Neogene floristic and climate changes. We do this by compiling published records of megafossil plant remains, because these offer better spatial and temporal resolution than do palynological records. Analyses of the Siwalik floral assemblages based on the distribution of the nearest living relative taxa suggest that a tropical wet evergreen forest was growing in a warm humid monsoonal climate at the deposition time. This qualitative interpretation is also corroborated by published CLAMP (Climate Leaf Analysis Multivariate Program) analyses. Here, we also reconstruct the climate by applying a new common proxy WorldClim2 calibration. This allows the detection of subtle climate differences between floral assemblages free of artefacts introduced by using different methodologies and climate calibrations. An analysis of the Siwalik floras indicates that there was a gradual change in floral composition. The lower Siwalik assemblages provide evidence of a predominance of evergreen elements. An increase in deciduous elements in the floral composition is noticed towards the close of the middle Siwalik and the beginning of the upper Siwalik formation. This change reflects a climatic difference between Miocene and Plio-Pleistocene times. This review helps us to understand under what paleoenvironmental conditions plant diversity occurred and evolved in the eastern Himalayas throughout the Cenozoic.

Species diversity of angiosperms (flowering plants) varies greatly among regions. Geographic patterns of variation in species diversity are shaped by the interplay of ecological and evolutionary processes. Here, using a comprehensive data set for regional angiosperm floras across the world, we show geographic patterns of taxonomic (species) diversity, phylogenetic diversity, phylogenetic dispersion, and phylogenetic deviation (i.e., phylogenetic diversity after accounting for taxonomic diversity) across the world. Phylogenetic diversity is strongly and positively correlated with taxonomic diversity; as a result, geographic patterns of taxonomic and phylogenetic diversity across the world are highly similar. Areas with high taxonomic and phylogenetic diversity are located in tropical regions whereas areas with low taxonomic and phylogenetic diversity are located in temperate regions, particularly in Eurasia and North America, and in northern Africa. Similarly, phylogenetic dispersion is, in general, higher in tropical regions and lower in temperate regions. However, the geographic pattern of phylogenetic deviation differs substantially from those of taxonomic and phylogenetic diversity and phylogenetic dispersion. As a result, hotspots and coldspots of angiosperm diversity identified based on taxonomic and phylogenetic diversity and phylogenetic dispersion are incongruent with those identified based on phylogenetic deviations. Each of these metrics may be considered when selecting areas to be protected for their biodiversity.

Plants classified as Near Threatened (NT) are at high risk of becoming threatened because of anthropogenic interference and climate change. Especially in conservation efforts, such species have however long been overlooked. Here, we obtained 98,419 precise occurrence points for 2442 NT plants in China, and used species richness, species complementarity, and weighted endemism that consider all, endemic and narrow-ranged species in order to identify the diversity hotspots of NT plants. Then we evaluated the conservation effectiveness of current nature reserves for them. Our results indicate that the diversity hotspots of NT plants were mainly confined to southwestern and southern China, and only 35.87% of hotspots and 71.5% of species were protected by nature reserves. Numerous hotspots in southwestern China (e.g., Sichuan, Yunnan, Guangxi, and Hainan) were identified as conservation gaps. Given that NT plants include large proportions of endemic and narrow-ranged species, they represent an important value in conservation priority. So, more conservation efforts in the future should be tilted towards NT plants. Additionally, when comparing with the recently updated NT list, there are already 87 species raised to threatened categories, while 328 species were lowered to least concern, 56 species were now categorized as data deficient, and 119 species considered as uncertain due to changes of scientific names. It is essential to carry out a continuous assessment of species' threatened categories to realize targeting conservation.

Cryptic species are commonly misidentified because of high morphological similarities to other species. One group of plants that may harbor large numbers of cryptic species is the quillworts (Isoëtes spp.), an ancient aquatic plant lineage. Although over 350 species of Isoëtes have been reported globally, only ten species have been recorded in China. The aim of this study is to better understand Isoëtes species diversity in China. For this purpose, we systematically explored the phylogeny and evolution of Isoëtes using complete chloroplast genome (plastome) data, spore morphology, chromosome number, genetic structure, and haplotypes of almost all Chinese Isoëtes populations. We identified three ploidy levels of Isoëtes in China-diploid (2n = 22), tetraploid (2n = 44), and hexaploid (2n = 66). We also found four megaspore and microspore ornamentation types in diploids, six in tetraploids, and three in hexaploids. Phylogenetic analyses confirmed that I. hypsophila as the ancestral group of the genus and revealed that Isoëtes diploids, tetraploids, and hexaploids do not form monophyletic clades. Most individual species possess a single genetic structure; however, several samples have conflicting positions on the phylogenetic tree based on SNPs and the tree based on plastome data. All 36 samples shared 22 haplotypes. Divergence time analysis showed that I. hypsophila diverged in the early Eocene (～48.05 Ma), and most other Isoëtes species diverged 3-20 Ma. Additionally, different species of Isoëtes were found to inhabit different water systems and environments along the Yangtze River. These findings provide new insights into the relationships among Isoëtes species in China, where highly similar morphologic populations may harbor many cryptic species.

Myanmar is one of the most biodiverse countries in the Asia-Pacific region due to a wide range of climatic and environmental heterogeneity. Floristic diversity in Myanmar is largely unknown, resulting in a lack of comprehensive conservation plans. We developed a database of higher plants in Myanmar derived from herbarium specimens and literature sources, and analyzed patterns of diversity inventories and collection inconsistencies, aiming to provide a baseline floristic data of Myanmar and act as a guide for future research efforts. We collected 1,329,354 records of 16,218 taxa. Results show that the collection densities at the township level was variable, with 5% of townships having no floristic collections. No ecoregion had an average collection density of greater than 1 specimen/km² and the lowest collection density was found in the Kayah-Karen Montane Rainforests, which covered 8% of Myanmar's total area. The highest sampling densities were found in Mandalay Region, Chin State, and Yangon Region. Despite floristic collections over the past three centuries, knowledge of the distribution of the vast majority of plant taxa remained limited, particularly for gymnosperms, pteridophytes, and bryophytes. More botanical surveys and further analyses are needed to better describe Myanmar's floristic diversity. An important strategy to promote knowledge of the biodiversity patterns in Myanmar is to improve the collection and digitalization of specimens and to strengthen cooperation among countries.

Independence among leaf economics, leaf hydraulics and leaf size confers plants great capability in adapting to heterogeneous environments. However, it remains unclear whether the independence of the leaf traits revealed across species still holds within species, especially under stressed conditions. Here, a suite of traits in these dimensions were measured in leaves and roots of a typical mangrove species, Ceriops tagal, which grows in habitats with a similar sunny and hot environment but different soil salinity in southern China. Compared with C. tagal under low soil salinity, C. tagal under high soil salinity had lower photosynthetic capacity, as indicated directly by a lower leaf nitrogen concentration and higher water use efficiency, and indirectly by a higher investment in defense function and thinner palisade tissue; had lower water transport capacity, as evidenced by thinner leaf minor veins and thinner root vessels; and also had much smaller single leaf area. Leaf economics, hydraulics and leaf size of the mangrove species appear to be coordinated as one trait dimension, which likely stemmed from co-variation of soil water and nutrient availability along the salinity gradient. The intraspecific leaf trait relationship under a stressful environment is insightful for our understanding of plant adaption to the multifarious environments.

Floral trait variation may help pollinators and nectar robbers identify their target plants and, thus, lead to differential selection pressure for defense capability against floral antagonists. However, the effect of floral trait variation among individuals within a population on multi-dimensional plant-animal interactions has been little explored. We investigated floral trait variation, pollination, and nectar robbing among individual plants in a population of the bumble bee-pollinated plant, Caryopteris divaricata, from which flowers are also robbed by bumble bees with varying intensity across individuals. We measured the variation in corolla tube length, nectar volume and sugar concentration among individual plants, and evaluated whether the variation were recognized by pollinators and robbers. We investigated the influence of nectar robbing on legitimate visitation and seed production per fruit. We found that the primary nectar robber (Bombus nobilis) preferred to forage on plants with long-tubed flowers, which produced less nectar and had lower sugar concentration compared to those with shorter corolla tubes. Individuals with shorter corolla tubes had comparatively lower nectar robbing intensity but higher visitation by legitimate visitors (mainly B. picipes) and higher seed production. Nectar robbing significantly reduced seed production because it decreased pollinator visits. However, neither pollination nor seed production differed between plants with long and short corolla tubes when nectar robbers were excluded. This finding suggests that floral trait variation might not be driven by pollinators. Such variation among individual plants thus allows legitimate visitors and nectar robbers to segregate niches and enhances population defense against nectar robbing in unpredictable conditions.

Dendrobium nobile is an important medicinal and nutraceutical herb. Although the ingredients of D. nobile have been identified as polysaccharides, alkaloids, amino acids, flavonoids and bibenzyls, our understanding of the metabolic pathways that regulate the synthesis of these compounds is limited. Here, we used transcriptomic and metabolic analyses to elucidate the genes and metabolites involved in the biosynthesis of carbohydrate and several secondary metabolites in the stems of D. nobile. A total of 1005 metabolites and 31,745 genes were detected in the stems of D. nobile. The majority of these metabolites and genes were involved in the metabolism of carbohydrates (fructose, mannose, glucose, xylulose and starch), while some were involved in the metabolism of secondary metabolites (alkaloids, β-tyrosine, ferulic acid, 4-hydroxybenzoate and chrysin). Our predicted regulatory network indicated that five genes (AROG, PYK, DXS, ACEE and HMGCR) might play vital roles in the transition from carbohydrate to alkaloid synthesis. Correlation analysis identified that six genes (ALDO, PMM, BGLX, EGLC, XYLB and GLGA) were involved in carbohydrate metabolism, and two genes (ADT and CYP73A) were involved in secondary metabolite biosynthesis. Our analyses also indicated that phosphoenol-pyruvate (PEP) was a crucial bridge that connected carbohydrate to alkaloid biosynthesis. The regulatory network between carbohydrate and secondary metabolite biosynthesis established will provide important insights into the regulation of metabolites and biological systems in Dendrobium species.

Verticillium wilt, caused by Verticillium dahliae, seriously restricts the yield and quality improvement of cotton. Previous studies have revealed the involvement of WRKY members in plant defense against V. dahliae, but the underlying mechanisms involved need to be further elucidated. Here, we demonstrated that Gossypium hirsutum WRKY DNA-binding protein 33 (GhWRKY33) functions as a negative regulator in plant defense against V. dahliae. GhWRKY33 expression is induced rapidly by V. dahliae and methyl jasmonate, and overexpression of GhWRKY33 reduces plant tolerance to V. dahliae in Arabidopsis. Quantitative RT-PCR analysis revealed that expression of several JA-associated genes was significantly repressed in GhWRKY33 overexpressing transgenic plants. Yeast one-hybrid analysis revealed that GhWRKY33 may repress the transcription of both AtERF1 and GhERF2 through its binding to their promoters. Protein-protein interaction analysis suggested that GhWRKY33 interacts with G. hirsutum JASMONATE ZIM-domain protein 3 (GhJAZ3). Similarly, overexpression of GhJAZ3 also decreases plant tolerance to V. dahliae. Furthermore, GhJAZ3 acts synergistically with GhWRKY33 to suppress both AtERF1 and GhERF2 expression. Our results imply that GhWRKY33 may negatively regulate plant tolerance to V. dahliae via the JA-mediated signaling pathway.

The previously released packages of the PhyloMaker series (i.e. S.PhyloMaker, V.PhyloMaker, and V.PhyloMaker2) have been broadly used to generate phylogenetic trees for ecological and biogeographical studies. Although these packages can be used to generate phylogenetic trees for any groups of plants and animals for which megatrees are available, they focus on generating phylogenetic trees for plants based on the megatrees provided by the packages. How to use these packages to generate phylogenetic trees based on other megatrees is not straightforward. Here, we present a new tool, which is called 'U.PhyloMaker', and a simple R script that can be used to easily generate large phylogenetic trees for both plants and animals at a relatively fast speed.

The role of regional species diversity in large-scale species invasions has been largely controversial. On the one hand, it has been proposed that diversity may facilitate invasion ("diversity begets diversity") because regions with higher diversity may indicate favorable conditions for many more species. On the other hand, high diversity may indicate high levels of niche occupation, thus making it more difficult for new species to invade. In the past, invasion biologists have evaluated how regional native and exotic richness are related. Here, we test whether the range size of exotic species may be constrained by regional native richness using plant data from three continental regions in the Northern Hemisphere, i.e., Europe, Eastern Asia, and North America. We found that regional native plant diversity is inversely related to the range size of exotic species. This result may be due to stronger species interactions such as competition in species-rich habitats that limit the establishment and spread of exotic species.