Background: Viburnum chinshanense is an endemic species found exclusively in the North-Central and South-Central regions of China. This species is a lush garden ornamental tree and is extensively utilized for vegetation restoration in rocky desertification areas. Results: In this study, we obtained 13.96 Gb of Oxford Nanopore data for the whole genome, and subsequently, by combining Illumina short-reads, we successfully assembled the complete mitochondrial genome (mitogenome) of the V. chinshanense using a hybrid assembly strategy. The assembled genome can be described as a circular genome. The total length of the V. chinshanense mitogenome measures 643,971 bp, with a GC content of 46.18%. Our annotation efforts have revealed a total of 39 protein-coding genes (PCGs), 28 tRNA genes, and 3 rRNA genes within the V. chinshanense mitogenome. The analysis of repeated elements has identified 212 SSRs, 19 long tandem repeat elements, and 325 pairs of dispersed repeats in the V. chinshanense mitogenome. Additionally, we have investigated mitochondrial plastid DNAs (MTPTs) and identified 21 MTPTs within the mitogenome and plastidial genome. These MTPTs collectively span a length of 9,902 bp, accounting for 1.54% of the mitogenome. Moreover, employing Deepred-mt, we have confidently predicted 623 C to U RNA editing sites across the 39 protein-coding genes. Furthermore, extensive genomic rearrangements have been observed between V. chinshanense and the mitogenomes of related species. Interestingly, we have also identified a bacterial-derived tRNA gene (trnC-GCA) in the V. chinshanense mitogenome. Lastly, we have inferred the phylogenetic relationships of V. chinshanense with other angiosperms based on mitochondrial PCGs. Conclusions: This study marks the first report of a mitogenome from the Viburnum genus, offering a valuable genomic resource for exploring the evolution of mitogenomes within the Dipsacales order.

Rhododendron platypodum Diels (Ericaceae) is a Chinese endemic and endangered species with high ornamental value. Here the complete chloroplast (cp) genome of R. platypodum was assembled and characterized. The cp genome is in a total length of 201,047 bp with the typical quadripartite structure of angiosperms, containing two inverted repeats (IRs) of 44,650 bp separated by a large single-copy (LSC) region of 109,134 bp and a small single-copy (SSC) region of 2613 bp. The whole cp genome of R. platypodum contains 143 genes, including 93 protein-coding genes, 42 transfer RNA genes and 8 ribosomal RNA genes. Phylogenetic analysis based on the coding sequences of cp genome within the Ericaceae family suggests that R. platypodum is closely related to R. delavayi.

The benefits of urban green space are socially widely recognized as a direct link between plant–microbe interactions and the maintenance of biodiversity, community stability, and ecosystem functioning. Nevertheless, there is a lack of knowledge about the factors influencing microbial communities in urban green spaces, especially those related to phyllosphere epiphytes and stem epiphytes. In this study, we analyzed the microbial community assembly in leaf and stem bark samples collected from Square, Road, Campus, and Park. Illumina sequecing of 16S amplicons was performed to characterize microbial diversity and composition. The α-diversity was significantly higher in the bark epiphytic community, compared to the phyllosphere. Moreover, urban greenspaces'type altered the way communities gathered. The main soil and air properties factors of the urban greenhouse (e.g. soil temperature, atmospheric moisture, air temperature) were shaping the characteristics of bacterial communities on the leaf surface and bark epiphytic. In addition, in the co-occurrence network analysis, keystone taxa were not mostly observed in abundant species, which may be necessary to maintain ecosystem functions. Finally, our findings provide a deeper understanding of the ecological dynamics and microbial interactions within plant phyllosphere and stem epiphytes microbiomes.

Natural regeneration is deemed essential for maintaining biodiversity and ecosystem stability. Previous studies, however, have primarily concentrated on regions exhibiting limited environmental and climatic variability, overlooking the classification of natural regeneration based on age and source. Research conducted at the mesoscale, characterized by increased environmental variability and the incorporation of neighborhood competition and understory-associated vegetation, enhances our comprehension of the multifaceted influences on natural regeneration. To comprehend this issue, this study implemented 60 plots, each measuring 20 m × 20 m, across five distinct areas of Chongqing, China. Twenty explanatory variables were chosen from five diverse categories: understory vegetation, neighborhood competition, stand structure, climatic factors, and environmental factors. And the naturally regenerated species were classified into seedlings and saplings, as well as endogenous and exogenous species, based on their age and origin. We examined the response of the different categories of natural regeneration to various factors and constructed a structural equation model (SEM) for significant factors to investigate their direct and indirect effects on natural regeneration. A total of 61 regenerated tree species belonging to 29 families and 42 genera were found in the study area, and the naturally regenerating species with high importance values were Quercus fabri, Robinia pseudoacacia, Alangium chinense, Cunninghamia lanceolata, and Ligustrum lucidum. It was found that neighborhood competition and understory-associated vegetation explained the largest proportion (more than 50%) of the variation in the different categories of natural regeneration, and forests with clumped distribution (W), a high mingling index (M) and strong competition (H) had a reduced natural regeneration capacity. Understory-associated herbs significantly reduced natural regeneration and the crowdedness index (C) significantly inhibited the understory-associated herbs, thus indirectly promoting natural regeneration. The shrub cover is significantly and positively correlated with the number of naturally regenerated plants and can be used as an indicator of a forest community’s regeneration potential. Understanding the differences in the importance of various factors at the mesoscale, as well as their direct and indirect impacts, can help us further comprehend the mechanisms of natural regeneration and provide a foundation for the sustainable development of forests.

Genetic diversity in endangered species is of special significance in the face of escalating global climate change and alarming biodiversity declines. Rhododendron platypodum Diels, an endangered species endemic to China, is distinguished by its restricted geographical range. This study aimed to explore genetic diversity and differentiation among its populations, gathering samples from all four distribution sites: Jinfo Mountain (JFM), Zhaoyun Mountain (ZYM), Baima Mountain (BMM), and Mao’er Mountain (MEM). We employed 18 pairs of Simple Sequence Repeat (SSR) primers to ascertain the genetic diversity and structural characteristics of these samples and further utilized 19 phenotypic data points to corroborate the differentiation observed among the populations. These primers detected 52 alleles, with the average number of observed alleles (Na) being 2.89, the average number of effective alleles (Ne) being 2.12, the average observed heterozygosity (Ho) being 0.57, and the expected heterozygosity (He) being 0.50. This array of data demonstrates the efficacy of the primers in reflecting R. platypodum’s genetic diversity. SSR-based genetic analysis of the populations yielded Ho, He, and Shannon index (I) values ranging from 0.47 to 0.65, 0.36 to 0.46, and 0.53 to 0.69, respectively. Notably, the ZYM population emerged as the most genetically diverse. Further analysis, incorporating molecular variance, principal component analysis, UPGMA cluster analysis, and structure analysis, highlighted significant genetic differentiation between the Chongqing (BMM, JFM, ZYM) and Guangxi (MEM) populations. Morphological data analysis corroborated these findings. Additionally, marked genetic and morphological distinctions were evident among the three Chongqing populations (BMM, JFM, and ZYM). This suggests that, despite the observed regional differentiation, R. platypodum’s overall genetic diversity is relatively constrained compared to other species within the Rhododendron genus. Consequently, R. platypodum conservation hinges critically on preserving its genetic diversity and protecting its distinct populations.

Understanding how assembly processes shape local plant assemblages from the potential species pool is crucial for biodiversity conservation and revegetation. Mountainous regions are global biodiversity hotspots with high levels of diversity, concentration, and vulnerability. Road construction in these areas poses ecological challenges, including habitat loss and reduced biodiversity. Feature-based ecology highlights non-biological filtering as a key driver of habitat-specific community formation. Analyzing trait structures and their association with the environment can reveal community assembly processes under specific environmental conditions. However, quantifying species-environment-traits interactions during community assembly on roadside slopes is still underexplored. In our study, 76 naturally recovered roadside slopes, 656 self-established plant communities and 113 plant species across ten functional traits, along with their environmental associations, in the karst mountain region of southwestern China, were examined. Our findings show that there are still abundant native plants with colonization potential settled on steep roadside slopes in karst mountain areas. Diffusion constraints stemming from distance to the core species pool, elevation, and differences in adjacent vegetation types emerged as key factors causing variations in species composition of self-established communities. The slope environment exerts strong selective pressures leading to a convergence pattern in traits related to dispersal and colonization while showing a divergence pattern in traits linked to competitive strategies and regeneration. These findings identify critical functional traits and environmental factors shaping roadside plant communities and illustrate the predictability of environmental filtering and fundamental community assembly. Overall, our study sheds light on the intricate interactions among assembly processes, functional traits, and environmental factors driving local plant assemblages in mountainous regions, providing insights for effective diversity conservation and revegetation strategies.