Corrigendum: Identifying hotspots of woody plant diversity and their relevance with home ranges of the critically endangered gibbon (Nomascus hainanus) across forest landscapes within a tropical nature reserve.

[This corrects the article DOI: 10.3389/fpls.2023.1283037.].

Identifying hotspots of woody plant diversity and their relevance with home ranges of the critically endangered gibbon (Nomascus hainanus) across forest landscapes within a tropical nature reserve.

Introduction: To achieve effective conservation objectives, it is crucial to map biodiversity patterns and hotspots while considering multiple influencing factors. However, focusing solely on biodiversity hotspots is inadequate for species conservation on a landscape scale. This emphasizes the importance of integrating hotspots with the home ranges of species to identify priority conservation areas. Methods: Compiling the vegetation data with environmental and anthropogenic disturbance data collected from kilometer-grid plots in Bawangling Nature Reserve, Hainan, China, we analyzed the spatial distribution of plant diversity (species richness and Shannon-Wiener index), as well as the main drivers affecting these patterns. We also investigated the spatial distribution of hotspots using a threshold approach and compared them with the home ranges of the flagship species, Hainan gibbon (Nomascus hainanus). Result: Climate and soil are predominant drivers shaping the spatial pattern of plant diversity in Bawangling Nature Reserve, surpassing the influence of anthropogenic disturbance and topographic factors. Both diversity indices exhibit a generally similar pattern with exceptions in surrounding areas of Futouling and Elongling. The hotspots identified by the Shannon-Wiener index showed a higher spatial overlap with the home ranges of Hainan gibbon compared to the species richness hotspots. The recently established Hainan gibbon Group E in 2019, located 8 km away from the original Futouling habitat, does not coincide with identified hotspots. Discussion: Our findings indicate that the hotspots of plant diversity within the habitat of Hainan gibbon Group E are relatively limited, emphasizing the necessity of giving precedence to its conservation. Integrating hotspots with the home ranges of critically endangered species offers decision-makers valuable information to establish rational conservation networks in the context of changing environments, as well as a reference for habitat restoration of species.

Soil microbes support Janzen's mountain passes hypothesis: The role of local-scale climate variability along a tropical montane gradient.

Tropical montane ecosystems are the centers of biodiversity, and Janzen proposed that mountain climate variability plays a key role in sustaining this biodiversity. We test this hypothesis for soil bacteria and fungi along a 265-1,400 m elevational gradient on Hainan Island of tropical China, representing diverse vegetation types from deciduous monsoon forest to cloud forest. We found that bacterial and fungal diversity declined as elevation increased, and the dissimilarity of both groups increased with increasing separation in elevation, although changes in bacteria were larger than in fungi. Seasonal alterations and the range of soil moisture in the growing season were found to be the dominant drivers of fungal richness and Shannon diversity, whereas soil pH was the major driver of bacterial diversity. Dissimilarities of bacterial and fungal communities were best predicted by climate, particularly seasonal changes in soil temperature, with weaker influences of soil physicochemistry and vegetation. The dominant effect of seasonality in soil temperature was further detected in cloud forests, which harbored a higher proportion of unique bacterial species and dissimilarity of bacterial and fungal communities. Our findings suggest that local-climate variability plays a crucial role in structuring the distribution of soil microbial communities along a tropical montane gradient, which generally supports Janzen's hypothesis. Such a sensitivity to climatic variability suggests that soil microbial communities along tropical montane gradients may shift in response to future climate scenarios.

Pollen morphology and its implication in the taxonomy of some selected taxa of the bi and tri-ovulate Euphorbiaceae of the Hainan Island by using multiple microscopic techniques.

The family Euphorbiaceae is one of the most taxonomically complex and diverse family among the angiosperm. Therefore, this study aims to document the pollen morphology of the Euphorbiaceae taxa collected from different geographical regions of the Hainan Island South China, to strengthen the taxonomy and support the subfamilial classification. The Euphorbiaceae includes 23 species and 10 genera of the bi-ovulate subfamily Phyllanthoideae and tri-ovulate Crotonoideae, Euphorbioideae, and Acalyphoideae were examined under light and scanning electron microscopy. The principal component analysis was performed by using six variables to show variation and relationships between the species. A significant variation was found in the pollen morphology (exine and colpus sculpturing). The croton-type pattern of the pollen was found the diagnostic trait of the Crotonoideae. The Euhphorboideae taxa were mostly homogenous however, variation was found in the muri pattern. The Acalyphoideae, have fossulate scabrate and verrucate exine sculpturing that can delimit from the rest of sub-families. The Phyllanthoideae, showed reticulate exine, tri to tetra-colporate having various colpus morphology. The maximum pollen size was found in Croton hirtus (59.49 × 60.86 µm) and minimum in Acalypha indica (10.86 × 73 µm). Similarly, the maximum colpus width was observed in Euphorbia pulcherrima (8.3 µm). Hence pollen traits have relevance in the taxonomy and phylogenetic of the family to define species boundaries at various taxonomic levels. This study can support and strengthen the taxonomy of subfamilies and fill the palynological gap of these taxa in Hainan Island and will contribute to future systematic studies of the Euphorbiaceae.

Differing Trade-Off Patterns of Tree Vegetative Organs in a Tropical Cloud Forest.

Functional trait ecology demonstrates the significance of the leaf economics spectrum in understanding plants' trade-off between acquisitive and conservative resource utilization. However, whether trait variations of different vegetative organs are coordinated and whether the plant economics spectrum is characterized by more than one vegetative organ remain controversial. To gain insights into these questions, within a tropical cloud forest in Hainan Island, a total of 13 functional traits of 84 tree species were analyzed here, including leaf, stem and root traits. By using standardized major axis (SMA) regression and principal components analysis, we examined the trait variations and correlations for deciphering plants' trade-off pattern. We found decreases of leaf phosphorus content, leaf nitrogen content and specific leaf area and increases of leaf mass per unit area (LMA), wood density and leaf thickness along the first principal component, while there were decreases of specific root length and specific root area and increases of root tissue density along the second principal component. Root phosphorus and nitrogen contents were significantly positively associated with the phosphorus and nitrogen contents of both stem and leaf. Wood density was significantly positively associated with LMA and leaf thickness, but negatively associated with leaf thickness and specific leaf area. Our results indicate that, in the tropical cloud forest, there is a "fast-slow" economic spectrum characterized by leaf and stem. Changes of nutrient trait are coordinated, whereas the relationships of morphological traits varied independently between plant above- and below-ground parts, while root nutrient traits are decoupled from root morphological traits. Our findings can provide an insight into the species coexistence and community assembly in high-altitude tropical forests.

Identification of key genes in the tumor microenvironment of lung adenocarcinoma.

The tumor microenvironment plays an important role in tumor development and progression, but the role of immune and stromal cells in this environment has not been sufficiently studied. In this study, we aimed to identify key genes associated with the microenvironment of lung adenocarcinoma (LUAD). Raw data for stromal and immune cells in malignant tumors were downloaded from The Cancer Genome Atlas (TCGA). These expression data were used to identify the differentially expressed genes (DEGs) in tissue samples of LUAD with high and low immune scores. A protein-protein interaction (PPI) network based on genes with significant differential expression was constructed. Additionally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to functionally annotate putative hub genes. These genes were assessed via Kaplan Meier analysis to determine their correlation with overall survival. In total, we identified 216 DEGs which were correlated with immune and stromal scores, including 30 hub genes which were identified based on the PPI network. Further analysis suggested that the expression levels of 10 of these genes were significantly correlated with overall survival of LUAD patients. These key hub genes included CCR2, CCR5, CD53, CYBB, HCK, IRF8, LCP2, PLEK, PTPRC, and TLR7. Moreover, the expression level of CCR2 was found to have strong prognostic value for LUAD patients. Additionally, high expression of CYBB was also correlated with better survival of patients with LUAD. The results of this study open several new avenues to explore in the treatment of LUAD.

2-(2-Phenylethyl)chromone derivatives: Promising α-glucosidase inhibitors in agarwood from Aquilaria filaria.

Twelve undescribed 2-(2-phenylethyl)chromone derivatives, including one pair of enantiomers, together with eleven known ones, were isolated from the EtOAc extract of agarwood originating from Aquilaria filaria. All structures were elucidated by spectroscopic (NMR, UV, IR, MS) methods and compared with reported data in literatures. Twenty-one compounds were assessed for α-glucosidase inhibitory activity, which showed inhibition of α-glucosidase with IC50 values ranging between 7.8 ± 0.3 to 137.7 ± 3.0 µM (Acarbose, 743.4 ± 3.3 µM; Genistein, 8.3 ± 0.1 µM). Our results expanded the structural diversity of 2-(2-phenylethyl)chromones from agarwood, and revealed the potential of 2-(2-phenylethyl)chromones as α-glucosidase inhibitors.

Upregulation of cervical carcinoma expressed PCNA regulatory long non-coding RNA promotes esophageal squamous cell carcinoma progression.

Cervical carcinoma expressed PCNA regulatory long non-coding (lnc)RNA (CCEPR) has recently been reported to play oncogenic roles in some common types of human cancer. However, the clinical significance of CCEPR mRNA expression levels in esophageal squamous cell carcinoma (ESCC) and the exact function of CCEPR in regulating the malignant phenotypes of ESCC cells have not been previously investigated. In the present study, CCEPR mRNA expression level was upregulated in ESCC tissues and cell lines, and overexpression of CCEPR was associated with advanced TNM stage, lymph node metastasis, and poor prognosis in ESCC. In vitro experiments showed that silencing CCEPR mRNA expression levels significantly suppressed the proliferation, migration, and invasion of ESCC cells, while inducing ESCC cell apoptosis. Furthermore, inhibition of CCEPR decreased the protein expression levels of matrix metalloproteinase (MMP)2 and MMP9 and inhibited epithelial-mesenchymal transition in ESCC cells. In conclusion, the results showed that CCEPR plays an oncogenic role in ESCC and suggests that CCEPR could be used as a potential therapeutic target for ESCC treatment.

Strong positively diversity-productivity relationships in the natural sub-alpine meadow communities across time are up to superior performers.

In experiments that test plant diversity-productivity relationships, the common practice of weeding unsown species and disallowing species colonization may have the unintended consequence of favoring priority effects that maintain niche complementarity in determining productivity. However, in naturally assembled communities where colonization occurs, resource competition may favor dominant traits, which eventually have the greatest influence on productivity. Here, in naturally developed long-term subalpine meadows (from 4-year to at least 40 years meadows) in the Qinghai-Tibetan Plateau, we investigated the relationships between species richness and productivity to testify whether positive diversity-productivity relationships can still exist in naturally developed long-term communities. We also measured five functional traits (specific leaf area, photosynthesis rate, leaf proline content, seed mass and seed germination rate) to calculate two functional diversity indices: community-weighted mean trait values (CWM) and Rao's quadratic entropy (RaoQ) which are highly correlated to functional traits of dominating species and variety of functional trait among all species. Finally, we quantified the relative contribution of species diversity, functional traits of dominating species and functional diversity among all species to productivity along the succession. We demonstrated strong positively diversity-productivity relationships in the natural sub-alpine meadow communities across time. The five traits of dominating species explained a large proportion (54-80%) of the variation in productivity during succession, whereas species diversity and functional diversity (FD) for each of the five traits explained much less (24-48% for species richness and 0-40% for FD for each of the five traits respectively). We found unequivocal evidence that significantly positive diversity-productivity relationships in the natural sub-alpine meadow communities across time are up to superior performers (dominant traits) in naturally developed communities where colonization occurs. As a result, understanding diversity-productivity relationships under the full range of community assembly processes therefore merits further investigation.

Human coronaviruses with emphasis on the COVID-19 outbreak.

Human coronaviruses are known as respiratory pathogens mainly associated with a range of respiratory diseases. In the past 18 years, the beginning of severe acute respiratory syndrome human coronavirus (SARS-HCoV), Middle East respiratory syndrome coronavirus (MERS-CoV) and now the (COVID-19) have driven the HCoV into the platform of the scientific community due to their high pathogenicity in humans. Our study about the HCoV has contributed extensively to the understanding of HCoV pathogenesis its outbreak and precautionary measurements mainly COVID-19. By the 16-February 2020, total existing diagnosis cases of COVID-19, in china now numbered around 57,255, total cumulative diagnosis is about 68,592, total existing suspicion is about 8228, a total severe existing disease 11,272, the total cumulative cure is about 9671 with more than 1666 cumulative deaths have been reported. The purpose of the review is to summarize the present knowledge on the viral diversity, reservoir hosts, and geographical distributions of Human coronavirus (COVID-19) in China.

Genetic diversity and genetic structure of Decalobanthus boisianus in Hainan Island, China.

Decalobanthus boisianus is a native plant of Hainan Island, China, which has caused considerable damage to tropical forest ecosystems in recent decades. Understanding the genetic diversity and structure of this species can facilitate uncovering the molecular mechanism of its invasive ability. Here, we collected 77 individuals of D. boisianus spanning 8 distribution areas with a gradient of human disturbance intensity (i.e., low, moderate, and high disturbance intensity groups) to assess patterns of genetic diversity and structure using inter simple sequence repeat (ISSR) markers. We found that a total of 220 loci were scored with 13 primers using ISSR methods, and that 198 loci were polymorphic. The genetic diversity of D. boisianus among these eight forests decreased with increasing human disturbance intensity. Over 70% of the total genetic variation was present within populations, while less than 30% of variation was found among populations. There was a high gene flow (1.27) among them due to a lack of effective geographic barriers. The mean Nei's genetic distance of D. boisianus populations was found to be relatively small (i.e., 0.07), and the average genetic similarity of the eight populations was high (i.e., 0.93). Our findings indicate that the genetic diversity of D. boisianus correlated to human disturbance density, and that D. boisianus populations in Hainan Island have frequent gene exchange. We suggest that reduce deforestation to decrease human disturbance may be a good way to prevent the invasion of D. boisianus.

Four new guaiane sesquiterpenoids from agarwood of Aquilaria filaria.

Six 8,12-epoxyguaiane sesquiterpenes (1-6), together with two known 2-(2-phenylethyl)chromone derivatives (7-8) were isolated from agarwood originating from Aquilaria filaria. Their structures were established by spectroscopic methods including IR, HRESIMS, 1D, and 2D NMR, and comparison with the published data. The absolute configuration of compound 1 was unambiguously determined by quantum chemical calculation of the electronic circular dichroism (ECD) spectrum. All compounds were tested for their α-glucosidase inhibitory activity and cytotoxicity. Compound 5 showed significant α-glucosidase inhibitory activity with IC50 value of 253.2 ±â€¯9.7 µM (Acarbose, 743. 4 ±â€¯3.3 µM). Compounds 2-4 displayed weak cytotoxicity against K562 tumor cell lines.

DNA barcoding analysis and phylogenetic relationships of tree species in tropical cloud forests.

DNA barcoding is a useful tool for species identification and phylogenetic construction. But present studies have far reached a consistent result on the universality of DNA barcoding. We tested the universality of tree species DNA barcodes including rbcL, matK, trnH-psbA and ITS, and examined their abilities of species identification and phylogenetic construction in three tropical cloud forests. Results showed that the success rates of PCR amplification of rbcL, matK, trnH-psbA and ITS were 75.26% ± 3.65%, 57.24% ± 4.42%, 79.28% ± 7.08%, 50.31% ± 6.64%, and the rates of DNA sequencing were 63.84% ± 4.32%, 50.82% ± 4.36%, 72.87% ± 11.37%, 45.15% ± 8.91% respectively, suggesting that both rbcL and trnH-psbA are universal for tree species in the tropical cloud forests. The success rates of species identification of the four fragments were higher than 41.00% (rbcL: 41.50% ± 2.81%, matK: 42.88% ± 2.59%, trnH-psbA: 46.16% ± 5.11% and ITS: 47.20% ± 5.76%), demonstrating that these fragments have potentiality in species identification. When the phylogenetic relationships were built with random fragment combinations, optimal evolutionary tree with high supporting values were established using the combinations of rbcL + matK + trnH-psbA in tropical cloud forests.

Vascular Epiphyte Diversity Differs with Host Crown Zone and Diameter, but Not Orientation in a Tropical Cloud Forest.

Vascular epiphytes are important components of biological diversity in tropical forests. We measured the species richness and abundance of vascular epiphytes along four vertical crown zones and five horizontal orientations on 376 trees, as well as the diameter at breast height (DBH) of host trees in tropical cloud forests in Bawangling, Hainan, China. The relationship between vascular epiphyte species richness and host tree DBH was assessed using a generalized linear model. There were 1,453 vascular individual epiphytes attributed to 9 families, 24 genera and 35 species, with orchids and pteridophytes dominating. Both the species richness and abundance of epiphytes significantly differed among the four crown zones for all collections and each host tree, suggesting that vertical microhabitats contribute to the distribution of epiphytes on host trees. Neither epiphyte abundance nor species richness differed among the eastern, southern, western, and northern orientations for all host trees; however, both richness and abundance were significantly higher for epiphytes that encircled host tree trunks. This suggests that morphological and physiological characteristics of the tree, but not microclimates probably contribute to the distribution of epiphytes on host trees. Epiphyte species richness was positively correlated with tree DBH across the six host tree species studied, with increases in DBH among smaller trees resulting in larger increases in richness, while increases in DBH among larger host trees resulting in more modest increases in ephiphyte richness. Our findings contribute support for a positive relationship between epiphyte species richness and host tree DBH and provide important guidance for future surveys of epiphyte community development.

Factors affecting the distribution pattern of wild plants with extremely small populations in Hainan Island, China.

Understanding which factors affect the distribution pattern of extremely small populations is essential to the protection and propagation of rare and endangered plant species. In this study, we established 108 plots covering the entire Hainan Island, and measured the appearance frequency and species richness of plant species with extremely small populations, as well as the ecological environments and human disturbances during 2012-2013. We explored how the ecological environments and human activities affected the distribution pattern of these extremely small populations. Results showed that the extremely small populations underwent human disturbances and threats, and they were often found in fragmental habitats. The leading factors changing the appearance frequency of extremely small populations differed among plant species, and the direct factors making them susceptible to extinction were human disturbances. The peak richness of extremely small populations always occurred at the medium level across environmental gradients, and their species richness always decreased with increasing human disturbances. However, the appearance frequencies of three orchid species increased with the increasing human disturbances. Our study thus indicate that knowledge on how the external factors, such as the ecological environment, land use type, roads, human activity, etc., affect the distribution of the extremely small populations should be taken for the better protecting them in the future.

Effects of competition and facilitation on species assemblage in two types of tropical cloud forest.

Competition and facilitation between tree individuals are two kinds of non-random processes influencing the structure and functioning of forest communities, but how these two plant-plant interactions change along gradient of resources or environments remains very much a matter of debate. We developed a null model to test the size-distance regression, and assessed the effects of competition and facilitation (including interspecific interactions, intraspecific interactions and overall species interactions) on each adult tree species assemblage [diameter at breast height (dbh) ≥5 cm] across two types of tropical cloud forest with different environmental and resource regimes. The null model test revealed that 17% to 27% tree species had positive dbh-distance correlations while 11% to 19% tree species showed negative dbh-distance correlations within these two forest types, indicating that both competition and facilitation processes existed during the community assembly. The importance of competition for heterospecific species, and the intensity of competition for both heterospecific and overall species increased from high to low resources for all the shared species spanning the two forests. The importance of facilitation for conspecific and overall species, as well as that the intensity of facilitation for both heterospecific and conspecific species increased with increasing low air temperature stress for all the shared species spanning the two forests. Our results show that both competition and facilitation processes simultaneously affect parts of species assemblage in the tropical cloud forests. Moreover, the fact that nearly 50% species assemblage is not detected with our approaches suggest that tree species in these tropical forest systems are assembled with multiple ecological processes, and that there is a need to explore the processes other than the two biotic interactions in further researches.

Within- and among-species variation in specific leaf area drive community assembly in a tropical cloud forest.

Specific leaf area (SLA) is a key functional trait reflecting the trade-off between resource capture and conservation, and has been identified as playing an important role in plant community assembly. Mechanistic models of community assembly state that the assemblage of species in a local community is controlled by environment filters operating on functional traits. We measured within- and among-species variation of SLA, and environmental conditions in a tropical cloud forest to explore how variation in this functional trait contributes to community assembly. SLA variation at the species level was also decomposed into alpha (within assemblage variation), and beta (across assemblage variation) values. SLA decreased with increasing solar irradiance (approximated using plant height) within the three study sites, and differed among the three sites both for within- and among-species comparisons. Mean plot SLA, accounting for both within and among species across the three sites, increased significantly in relation to air temperature but not local photosynthetic photon flux density and soil total phosphorus. Alpha SLA decreased with increasing solar irradiance within the three sites and beta SLA differed among the three sites. Our results clearly demonstrate that light and air temperature are key environmental factors involved in organizing plant species within and among communities in tropical cloud forests. The strong relationship between both intra- and interspecific variation in SLA and environmental conditions strongly confirms the role of trait variation in the assembly of plant species in tropical cloud forest communities via environment filtering related to light availability and air temperature.