The geographical distributions of plant species are being actively reshaped by climate change. Castanopsis eyrei, a cornerstone species of subtropical evergreen broad-leaved forests in China, plays a critical role in community assembly and carbon sequestration. Understanding the key factors driving shifts in its potential distribution is vital to maintain biodiversity and formulate effective conservation strategies. Here, by comparing the soil-topographic-bioclimatic model with the bioclimatic-only model, we found that soil (base saturation) and climate (annual mean temperature, precipitation of the coldest quarter) jointly constrain the potential distribution of C. eyrei. The bioclimate-only model predicted larger suitable areas, highlighting that non-climatic variables can substantially alter the potential distribution forecasts. For the period 2041-2060, both models projected relatively stable distributions under low-emission (SSP1-2.6) and high-emission (SSP5-8.5) scenarios, with the latter showing greater northward expansion likely associated with increased temperature and precipitation. The soil-topographic-bioclimatic models showed lower inter-scenario variability, suggesting that soil and topographic factors may buffer against the effects of climatic change within our modeling framework. Our study demonstrates the necessity of integrating non-climatic variables into species distribution models, and provides projections to guide future monitoring and conservation efforts for C. eyrei.

IntroductionThe impact of climate change on the distribution of Camellia japonica, an economically important ornamental shrub, is a critical concern for conservation. This study aims to explore its potential geographic distribution under climate change in China.MethodsWe used 56 carefully screened and spatially thinned occurrence records in a Maximum Entropy (MaxEnt) model. After filtering for multicollinearity, ten environmental variables were retained. Future projections were made for the SSP245 and SSP585 scenarios for the 2050s and 2070s.ResultsThe model showed high predictive accuracy (AUC = 0.958). Temperature factors, particularly Bio6 and Bio2, were the main determinants. Under current conditions, highly suitable habitats are mainly concentrated in eastern coastal regions. Future projections indicate a severe contraction of suitable habitats by the 2070s, with reductions of 80.1% and 90.9% under SSP245 and SSP585, respectively.DiscussionThe findings suggest a severe habitat contraction for wild C. japonica populations under future climate scenarios, with limited evidence of a range shift. This highlights their vulnerability and the urgent need for targeted, spatially explicit conservation strategies.

To screen the optimal in vitro pollen germination medium for Ilex cornuta and support breeding programs, pollen was used in single-factor experiments to determine suitable concentrations of sucrose, boric acid (H₃BO₃), and calcium chloride (CaCl₂), as well as culture time. An orthogonal design then tested their interactions and identified the optimal medium. Three staining methods — TTC (2,3,5-triphenyltetrazolium chloride), methylene blue, and I₂-KI (iodine–potassium iodide) — were compared for pollen viability. The flowering period of I. cornuta lasted about 30 days from late March to mid-April, peaking in mid-April with over half the flowers opening within 15 days. Single-factor tests showed suitable ranges: 0–50 g/L sucrose, 30–90 mg/L H₃BO₃, and 0–100 mg/L CaCl₂; optimal germination time was 16 h. The orthogonal test gave the highest germination rate (11.27%) in medium containing 50 g/L sucrose + 60 mg/L H₃BO₃ without CaCl₂. Pollen viability was 22.73% with methylene blue, 52.23% with TTC, while I₂-KI produced no obvious change. Thus, the optimal medium is 50 g/L sucrose + 60 mg/L H₃BO₃ (CaCl₂ omitted), with 16 h culture. TTC is suitable for rapid estimation. This study provides a reliable protocol for pollen quality assessment in I. cornuta to support future hybridization.

Recent advances in high-throughput sequencing have enabled detailed characterization of plant mitochondrial genomes. Here, we assembled and analyzed the mitochondrial genome of Quercus chenii Nakai, a key oak species in Fagaceae, using Illumina NovaSeq6000. The genome consists of a 364,958 bp linear and a 53,677 bp circular chromosome, totaling 418,635 bp with a GC content of 45.6

ABSTRACT Our understanding of the mechanisms that maintain phyllosphere microbial diversity in natural systems remains far less developed than our understanding of belowground microbiomes. This knowledge gap hinders our comprehension of growth dynamics in the Fagaceae, a predominant tree family in subtropical regions, and the critical role it plays as a major forest community assembly. Here, we tested leaves from Castanopsis eyrei , a widespread subtropical Fagaceae species in south-eastern China, sampled across multiple ages within a forest dynamics plot on Mt. Huangshan. Using third-generation sequencing of full-length bacterial 16S rRNA genes and fungal ITS regions, we characterized the associated phyllosphere microbiota. We found that phyllosphere fungal diversity was high, dominated by Teratosphaeriaceae, Trimorphomycetaceae, and Bulleribasidiaceae, while bacterial diversity was lower and primarily comprised Beijerinckiaceae, Isosphaeraceae, and Acidobacteriaceae. Habitat, rather than host age, emerged as the principal factor influencing fungal and pathogen diversity. Linear mixed-effects models revealed a negative relationship between C. eyrei biomass and phyllosphere pathogen diversity. Co-occurrence network analysis showed that C. eyrei saplings supported the most complex network structure, with Recuromyces acting as a key pathogenic fungus, serving as both a module hub and a connector across all age classes. Overall, these findings highlight the ecological importance of habitat in shaping phyllosphere microbial diversity and underscore the interplay between host function and the maintenance of microbial diversity. IMPORTANCE Plant surfaces host diverse microbial communities that significantly impact host health and overall forest productivity. However, mechanisms maintaining phyllosphere microbial diversity and their consequences for host plants remain poorly understood. Employing a three-generation high-throughput sequencing approach, we investigated the phyllosphere fungal and bacterial diversity across different microhabitats and ages of Castanopsis eyrei , a common species in subtropical forest, China. Our results underscore the presence of exceptionally high microbial diversity on the plant surface, elucidating the taxonomic composition at the family level of key host microorganisms. Furthermore, our observation of a negative correlation between host performance and phyllosphere pathogens underscores the potential self-limiting ability of plants.

Understanding the population dynamics and interspecific interactions in subtropical forests is crucial for uncovering the underlying mechanisms of species coexistence and community stability. Two censuses were conducted between 2018 and 2023 in a 9.6 ha subtropical evergreen broad-leaved forest dynamics plot situated in Mount Wuyi, southeastern China. Utilizing co-occurrence networks and long-term data, we examined the relationship between species interactions and their contributions to community assembly. Our findings reveal that high mortality rates among small-diameter individuals have created ecological niches, facilitating the establishment of 12 new species between 2018 and 2023. A generalized linear mixed-effects model showed positive relationships between sapling abundance and conspecific neighbor density. Co-occurrence networks demonstrated a shift toward higher positive interactions but reduced modularity, indicating a more integrated yet less stable community structure. Despite their low abundance, rare species demonstrated significant roles in network connectivity and stability, underscoring their status as keystone species. Additionally, the significant correlations between topographic factors and species richness highlighted the role of environmental filtering in shaping community composition. Our findings contribute to a deeper understanding of subtropical forest community dynamics, emphasizing the importance of long-term monitoring to unravel the complex interactions between populations and their environmental conditions. This study represents the first long-term observational experiment conducted in a subtropical secondary forest, providing valuable insights into the dynamics of forest community assembly in this region.

This study assessed air quality in Yancheng, China, using moss biomonitoring. The moss species, Haplocladium microphyllum was chosen, and mosses were collected from 67 sites across Yancheng during July and August 2022. The concentrations of Al, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn, V, and nitrogen in mosses were determined, and the spatial distribution and temporal trends of atmospheric trace metals and nitrogen deposition in Yancheng were explored by comparing the current data with that of a similar study conducted in 2017. In 2022, high concentrations of metals and nitrogen in mosses were found in northern and southwestern Yancheng, whereas lower concentrations were observed in southern and southeastern Yancheng for metals and central Yancheng for nitrogen. Since 2017, the moss concentrations of Zn, Cu, Ni, and Cr have increased, while that of V has declined, with no notable changes observed in other metals and nitrogen. Contamination factor analysis indicated that Pb and Cu contamination levels escalated from moderate and slight (2017) to severe and moderate (2022), respectively. The Positive Matrix Factorization (PMF) model identified five dominant contamination sources of metals and nitrogen in 2022 mosses: natural source (21.4%), traffic emission (17.84%), fuel combustion derived from coal and heavy oil (22.71%), agricultural activities (19.37%), and industrial activities (18.68%). This study highlights the significance of moss biomonitoring, along with data analysis and emission source inventories, as essential tools for evaluating air quality in Yancheng.

As an important component of forest biodiversity, the phyllosphere microbiome plays an essential role in maintaining forest health, nutrient cycling, and plant resilience. However, the assembly and maintenance of its high community diversity remain poorly understood. In this study, we employed high-throughput sequencing to investigate the microbial communities associated with 61 phyllosphere samples from 12 dominant tree species and 25 samples from rare and occasional species in the subtropical forests of Mt. Huangshan, a key biodiversity hotspot in China. We first assessed the diversity of bacterial and fungal communities and explored their relationships with surrounding plant diversity, host functional traits, and topographic factors. We then quantified the ecological processes shaping phyllosphere microbial community assembly and identified biotic and abiotic factors that potentially regulate these dynamics. The results indicate that bacterial and fungal communities are governed predominantly by homogeneous selection. Specifically, the maintenance of bacterial diversity is driven mainly by plant community diversity, whereas fungal diversity responds more strongly to host traits (e.g., leaf C: N and pH). Moreover, fungal assembly is further constrained by dispersal limitation; accordingly, environmental selection accounts for a much smaller variation explanation rate in fungal diversity than in bacterial diversity. These results suggest that phyllosphere microbial diversity and its assembly processes are tightly linked to forest structural complexity and landscape heterogeneity. Finally, Mantel test results suggest that the homogeneous selection acting on bacterial communities assembly may be weaker through the mediating effects of fungal diversity, topographic factors, and host chemical traits. In contrast, bacterial diversity can directly reverse fungal community assembly from being controlled by selection to a neutral process. This study provides new insight into phyllosphere fungi-bacteria interactions, contributing to a deeper understanding of aboveground biodiversity maintenance mechanisms in subtropical forests.

In angiosperms, plastomes are typically maternally inherited and transmitted primarily through seeds, leading to limited gene flow of plastid DNA. This restriction often results in a stronger geographic structure for plastid DNA compared to nuclear DNA, especially in wind-pollinated plants with large seeds, such as oaks. However, previous studies on East Asian Cerris oaks (Quercus subsection Campylolepides; Q. acutissima, Q. chenii, and Q. variabilis) found only three deep-diverging plastid lineages distributed randomly across their range, obscuring any clear phylogeographic structure. In this study, we performed a comprehensive sampling of whole plastomes to re-examine the phylogeographic pattern of East Asian Cerris oaks. Across 761 samples, we identified 163 haplotypes clustered into 15 clades, 11 of which were shared among species. The crown-group radiation of the Campylolepides core plastid clade appears to predate the formation of modern-day species, suggesting that the previously identified deep-diverging plastid lineages may reflect the retention of ancestral polymorphism. Under this interpretation, these lineages are expected to be randomly distributed across the species’ range. Within eight plastid clades occurring in more than five populations, we detected a significant phylogeographic structure. The consistent east-west differentiation observed in several widely distributed clades reflects allopatric divergence followed by localized gene exchange among sympatric species in multiple isolated refugia. Additionally, we found that different oak species co-occurring at the same site exhibited higher levels of haplotype sharing compared to those in nearby populations. The haplotypes shared within mixed-species populations displayed narrow distributions and were estimated to have originated well after the speciation events, likely due to Pleistocene plastome capture. Our findings highlight that in East Asian Cerris oaks, strong phylogeographic structure is evident primarily within major plastid clades rather than within individual species. Both shared ancestral polymorphism and historical introgression may have contributed to shaping the phylogeographic patterns of these species.

This study investigated leaf phenotypic variation in oak species to better understand how different groups of oaks adapt to diverse environmental conditions. We examined the leaf phenotypic traits of six oak populations in two mixed forests with differing species compositions: Zijin Mountain in Jiangsu Province, composed of Quercus acutissima, Q. variabilis, and Q. fabri; and Youhua Village in Anhui Province, consisting of Q. acutissima, Q. chenii, and Q. fabri. The results indicated that species in the Cerris group (Q. acutissima, Q. chenii, and Q. variabilis) exhibited stable leaf morphology and higher fluctuating asymmetry (FA), suggesting adaptation to stable environments. In contrast, Q. fabri from the Quercus group showed higher phenotypic plasticity and lower FA, indicating a strategy for adapting to dynamic environments. The study also explored the relationship between FA and phenotypic plasticity, revealing that while both traits are influenced by environmental stress, phenotypic plasticity allowed for more flexible responses to environmental change. Additionally, our research highlighted the role of hybridization and genetic coadaptation in influencing developmental stability, with higher hybridization rates in Q. fabri leading to greater morphological variability. These findings underscore the importance of environmental factors, genetic variation, and hybridization in shaping the adaptive strategies and phenotypic traits of oak species, providing valuable insights into the complexities of adaptation and species identification.

The plant species in Huangshan Mountain (Mt. Huangshan) are abundant. Nevertheless, a comprehensive analysis of the relationship between biodiversity and environmental factors is lacking. This study aimed to analyze how multiple factors affect biodiversity and explain the mechanisms underlying community assembly processes and species maintenance. Thus, we compared the different biodiversities among Evergreen Broadleaf Forest (EBF), Deciduous Broadleaf Forest (DBF), and Mixed Needleleaf and Broadleaf Forest (MNBF) in a total of 75 plots in each community using a non-parametric Wilcoxon rank-sum test. Then, we employed Mantel tests to quantify the influence of ecological conditions, including spatial predictors, topographical variables, soil composition, and climate factors, on the three forest communities. Our findings revealed the following: (1) The species diversity and phylogenetic diversity within the EBF and MNBF were found to be higher than that in the DBF. The functional richness (FRic) in the MNBF was higher compared to the other two communities, whereas the functional evenness (FEiv), functional divergence (FDiv), and functional dispersion (FDis) in the DBF were the highest. (2) The species diversity of different canopy plants was positively correlated with phylogenetic diversity and functional richness, yet negatively correlated with FEve, FDis, and FDiv. Phylogenetic diversity exhibited a negative correlation with functional diversity for both total and shrub layers, whereas it showed a positive correlation with functional diversity for the tree layer. The type of forest canopy exhibited the strongest correlation with functional diversity. (3) In the redundancy analysis, environmental factors had a stronger influence on biodiversity than spatial distance, indicating that deterministic processes had a greater impact than random processes. The findings underscore the importance of key factors that are often overlooked in the work of protecting Mt. Huangshan, such as elevation, aspect, total phosphorus (TP), and precipitation of the driest month (Bio.14) etc. This provides theoretical guidance for the ecological restoration of forest vegetation in Mt. Huangshan.

The long-lived angiosperm Quercus L. (Oaks) have emerged as promising model organisms for investigating adaptive divergence and ecological environmental interactions due to their longevity and large genetic diversity as well as recurrent gene flow among species with diverse natural habitats. Until recently, numerous genomic studies by new high-throughput sequencing platforms have provided access to link genes with ecological and physiological traits. However, the genetic and epigenetic mechanisms underlying the adaptive evolution of oak trees are still poorly understood. In this review, we summarise the current progress of reported oak genomes and inheritance systems, analysing the epigenetics and genetic structure of oaks. We review evidence regarding the genetic mechanism linking introgressive hybridisation and reproductive isolation for a better understanding of adaptive divergence and defining speciation in oaks. Furthermore, we also discuss the interaction and evolution between oaks, other organisms and the environment to explore the adaptive strategies and coevolutionary mechanisms among them. Through the impact of this article, hopefully, a distinctive avenue could be established to further study the inheritance, ecology and multidimensional evolution of oaks.

Hybridization is a common phenomenon in plants, contributing to various outcomes that impact genetic diversity and species dynamics. To delve into these effects, we focused on four oak species: Quercus acutissima, Q. variabilis, Q. fabri, and Q. serrata. Using three genomic markers, we explored genetic diversity, hybrid identity, and introgression among these species. Our study revealed the high values of allelic richness, heterozygosity and number of private alleles for the populations investigated. Notably, gene flow is most active in the nuclear genome (NmnDNA = 4.82), followed by the chloroplast genome (NmcpDNA = 1.12), with the mitochondrial genome (NmmtDNA = 0.33) showing the most restricted gene flow. In the Quercus group, hybrids displayed higher genetic diversity and lower interspecific differentiation, particularly in nuclear and chloroplast genomes. Moreover, hybridization-induced leaf morphological variation further blurred species boundaries, complicating classification. In the Cerris group, asymmetric gene flow was observed, likely influenced by differences in pollen and seed dispersal abilities. This led to variations in the direction and intensity of gene flow among species. Our analysis identified various individual types, including purebreds and different generations of hybrids, all exhibiting hybrid vigor. Furthermore, our findings indicated that hybrid individuals possess phenotypic advantages, particularly in leaf width and leaf width to circumference ratio. These traits showed significant associations with environmental factors, notably longitude and latitude. Overall, our study highlights the importance of considering the effects of hybridization in oak forest conservation and taxonomy. We recommend further research to explore seed and pollen dispersal patterns through comprehensive genomic and landscape genetic analyses.

The plant pathogenic fungi diversity colonizing plant leaves has been largely understudied, creating a knowledge gap in understanding relationships between plant-pathogen and plant growth trade-offs. Here, we investigated the diversity of phyllosphere pathogenic fungi across 84 individuals from 12 dominant species in a subtropical forest and tested how leaf functional traits and plant ecological strategies (CSR theory) influence pathogen communities. High-throughput sequencing and FUNGuild classification were used to quantify pathogenic fungal diversity, while key traits were used a compute CSR strategy scores. We found that host species, rather than habitat, exerted a stronger influence on phyllosphere pathogenic fungi diversity. Leaf functional traits, including pH, C:N, and dry weight, were shown to affect phyllosphere pathogen diversity. However, stochastic processes primarily drove the spatial variation in phyllosphere pathogenic community assembly. Regression analyses revealed a significant negative association between the relative proportion of Ruderal strategies and pathogen diversity. In other words, as the proportion of traits associated with fast growth and high reproductive potential (i.e., ruderal strategies) increased, pathogen richness and diversity significantly decreased. This counterintuitive finding suggests that, despite expectations of lower defense investments, fast-growing ruderal species may experience reduced pathogen colonization—possibly due to rapid leaf turnover or other mechanisms that limit pathogen establishment. Finally, Variance partitioning further indicated that variation in pathogen diversity was more strongly structured by plant species identity than by spatial or taxonomic scales. Family and intraspecific level explained the highest degree of variation. Our findings provide new insights into how host traits mediate plant–pathogen interactions, with implications for forest management and the conservation of plant diversity in subtropical forests.

Accurate estimation of aboveground biomass (AGB) in tree–shrub communities is critical for quantifying forest ecosystem productivity and carbon sequestration potential. Although generalized allometric equations offer expediency in natural forest AGB estimation, their neglect of interspecific variability introduces methodological pitfalls. Precise AGB prediction necessitates resolving two biological constraints: phylogenetic conservation of allometric coefficients and ontogenetic regulation of scaling relationships. This study establishes an integrated framework combining the following: (1) phylogenetic signal detection (Blomberg’s K/Pagel’s λ) across 157 species’ allometric equations, revealing weak but significant evolutionary constraints (λ = 0.1249, p = 0.0027; K ≈ 0, p = 0.621); (2) hierarchical error decomposition of 9105 stems in a Mt. Wuyishan forest dynamics plot (15 species), identifying family-level error stratification (e.g., Theaceae vs. Myrtaceae, Δerror > 25%); (3) ontogenetic trajectory analysis of Castanopsis eyrei between Mt. Wuyishan and Mt. Huangshan, demonstrating significant biomass deviations in small trees (5–15 cm DBH, p < 0.05). Key findings resolve the following hypotheses: (1) absence of strong phylogenetic signals validates generalized models for phylogenetically diverse communities; (2) ontogenetic regulation dominates error magnitude, particularly in early developmental stages; (3) differential modeling is recommended: species-specific equations for pure forests/seedlings vs. generalized equations for mixed mature forests. This work establishes an error hierarchy: ontogeny > taxonomy > phylogeny, providing a mechanistic basis for optimizing forest carbon stock assessments.

Parrotia subaequalis is a rare and endangered deciduous tree native to China, valued for its vibrant autumn foliage and ornamental appeal. Its leaves exhibit striking coloration, ranging from red to yellow and purple, yet the physiological and molecular mechanisms behind this variation remain poorly understood. Here, we combined transcriptomic, metabolomic, and physiological analyses to investigate pigment changes within the yellow leaf phenotype of P. subaequalis. Our findings revealed significant differences in gene expression and metabolic profiles between yellow and green leaves, particularly in starch and sucrose metabolism, photosynthesis, and carbon metabolism. Yellow leaves exhibited reduced photosynthetic capacity and carotenoid levels, alongside increased D-glucose concentration. These findings suggest that visible color transitions are likely driven by coordinated changes in carbohydrate metabolism, photosynthetic function, and organic compound accumulation. This study provides novel insights into the molecular and physiological mechanisms governing leaf pigmentation in an endangered tree, with useful information relevant to their conservation and sustainable utilization.

Ilex chinensis Sims. is an evergreen tree species native to China and mainly distributed in the region south of the Qinling Mountains and the Huai River. This species has important ornamental, medicinal, ecological, and economic values, and plays a positive role in improving the environment and people’s lives. To reveal the genetic diversity and genetic structure of 401 individuals from 14 populations in the major distribution area of I. chinensis, 11 pairs of SSR primers were selected for PCR amplification. The products were then subjected to capillary electrophoresis, and the genetic diversity of Ilex individuals was analyzed using relevant software. The results showed that the genetic diversity of I. chinensis was at a moderate-to-high level. A total of 54 alleles were detected at 11 SSR loci in the 14 Ilex populations, with an average of 4.831 alleles per locus. AMOVA analysis indicated that the genetic variation of I. chinensis populations mainly originated within populations. A STRUCTURE analysis divided the 401 I. chinensis individuals into four different genetic clusters. The unweighted pair group methods using arithmetic averages (UPGMA) clustering based on Nei’s genetic distance revealed that the population from Xinping of Yuxi, Yunnan Province (XP), and the population from Longan of Qianxinan, Guizhou Province (LoA) were located in the outermost layer of the phylogenetic tree, indicating the furthest genetic relationship between these two population and other populations. The remaining populations could be roughly divided into two groups. Principal coordinate analysis (PCoA) demonstrated that the 401 individuals were clearly divided into three groups, which was consistent with the results of the STRUCTURE analysis and UPGMA clustering. This study identified the hotspots of genetic diversity of I. chinensis, as well as units for the conservation of individuals. It also revealed the patterns of genetic variation and population distribution of I. chinensis in different regions, providing a molecular basis for the geographical zoning and formulation of breeding programs for I. chinensis, as well as germplasm resource management.

High temperature affects yield and quality of vegetable crops. Thermotolerant plants have excellent systems for identifying molecular mechanisms of heat responsive. In this paper, Various heat resistance indexes of thermotolerant (‘14’) and thermosensitive (‘02’) cucumber plants were observed at seedling stage, and the similarities and differences of regulatory genes were detected by transcriptome, so as to provide a train of thought for studying the effects of heat stress on the internal mechanism of cucumber. Leaf orientation, photosystem, water loss, ROS of ‘14’ plants displayed enhancer responsive than that of ‘02’ plants under high temperature. In corresponding, transcriptome analysis shown that genes in photosynthesis, chlorophyll metabolism and water homeostasis were upregulated in ‘14’ plants, but downregulated in ‘02’ plants. The content of ZR, BR and JA of ‘14’ plants was more than that of ‘02’ plants, GA increased in both but higher in ‘14’, IAA and GA were boosted by heat in ‘14’ and ‘02’ after high temperature stress. Further correlation and interaction analysis revealed that a small number of transcription factor family genes and the metabolic pathways corporately regulate heat responsive. Our study revealed different phenotypic and physiological mechanisms of heat response in thermotolerant and thermosensitive cucumber plants, revealed different expression profiles and preference metabolic pathways between thermotolerant and thermosensitive plants. The transcription factors and genes that involved in heat resistance were analyzed comprehensively. Those results enhanced our understanding on the molecular mechanisms of high temperature responsive in cucumber.