Background: Dendrobium devonianum is a traditional Chinese medicinal herb with notable ornamental and medicinal value. Methods: In this study, transcriptomic and metabolomic approaches were employed to investigate gene expression and secondary metabolite changes during four developmental stages of D. devonianum flowers. Results: Metabolomic analysis identified 1186 distinct metabolites, with flavonoid compounds being the most abundant category (213 types). Transcriptomic analysis revealed 31 differentially expressed genes associated with flavonoid biosynthesis and flavonoid and flavonol biosynthesis pathways. Among these, key genes regulating flavonol synthesis, including F3H (Unigene0077194) and FLS (Unigene0062137), exhibited high expression levels in the early developmental stage (S1). Conclusions: Flavonoids serve as the major active components in D. devonianum flowers, exhibiting a wide range of pharmacological properties. This study provides valuable insights into the molecular mechanisms driving flavonoid accumulation in D. devonianum, offering a foundation for further functional studies and applications in ornamental and medicinal plant research.

Dendrobium devonianum is an important medicinal plant, rich in flavonoid, with various pharmacological activities such as stomachic and antioxidant properties. In this study, we integrated metabolome and transcriptome analyses to reveal metabolite and gene expression profiles of D. devonianum, both green (GDd) and purple-red (RDd) of semi-annual and annual stems. A total of 244 flavonoid metabolites, mainly flavones and flavonols, were identified and annotated. Cyanidin and delphinidin were the major anthocyanidins, with cyanidin-3-O-(6″-O-p-Coumaroyl) glucoside and delphinidin-3-O-(6″-O-p-coumaroyl) glucoside being the highest relative content in the RDd. Differential metabolites were significantly enriched, mainly in flavonoid biosynthesis, anthocyanin biosynthesis, and flavone and flavonol biosynthesis pathways. Transcriptomic analysis revealed that high expression levels of structural genes for flavonoid and anthocyanin biosynthesis were the main reasons for color changes in D. devonianum stems. Based on correlation analysis and weighted gene co-expression network analysis (WGCNA) analysis, CHS2 (chalcone synthase) and UGT77B2 (anthocyanidin 3-O-glucosyltransferase) were identified as important candidate genes involved in stem pigmentation. In addition, key transcription factors (TFs), including three bHLH (bHLH3, bHLH4, bHLH5) and two MYB (MYB1, MYB2), which may be involved in the regulation of flavonoid biosynthesis, were identified. This study provides new perspectives on D. devonianum efficacy components and the Dendrobium flavonoids and stem color regulation.

The present study explored the regularities of the path and network structure of surface runoff formed under the influence of urban surface landscapes. We used unmanned aerial vehicle sensors to examine terrain and land use/cover change. The sub-catchments of a typical city, Luohe, China, were evaluated for the effect of landscape on surface runoff. Landscape and topographic parameters from 166 urban sub-catchments in Luohe were obtained by measuring digital surface models and orthophoto maps. The minimum cumulative resistance model was used to simulate potential runoff and 491,820 potential runoff paths, connected upstream and downstream, were obtained in 166 sub-catchments. The chi-square test was used to compare simulation runoff paths and actual runoff depth, with the results showing that they led to the same distribution trend. When the gravity coefficient was greater than 18.93, path disconnection occurred among 166 sub-catchments, with a decrease in channels. The potential runoff distribution appeared in aggregation; as the gravity coefficient increased from low to high, aggregation showed a trend of increasing initially but subsequently decreasing. The initial runoff formed sub-catchments with high gravity coefficients, then accumulated and spread to the others. It is important that proper measures are taken to establish a unified planning of the city’s surface landscape in order to produce suitable surface runoff distribution.

To investigate interspecific variation in heat tolerance and underlying adaptation mechanisms in Rhododendron, three-year-old potted seedlings of eight taxa, representing four subgenera within the genus Rhododendron, were subjected to 40 °C high-temperature stress. Heat tolerance was comprehensively assessed using phenotypic observation, chlorophyll fluorescence imaging, microscopic examination, and physiological measurements. Results revealed that leaf damage in Rhododendron oldhamii and Rhododendron × pulchrum reached grade III, whereas Rhododendron latoucheae exhibited only grade II injury with rapid recovery. Chlorophyll fluorescence analysis showed a significant decrease in the maximum quantum efficiency of PSII (F_v/F_m) in R. liliiflorum and R. × pulchrum, followed by rapid recovery, while R. latoucheae maintained stable F_v/F_m values. Stomatal closure occurred in all taxa post-stress; stomatal characteristics of R. liliiflorum and R. simiarum remained stable, and leaf tissue structure was least affected in R. kiangsiense. R. × pulchrum demonstrated the most pronounced structural recovery. Physiologically, R. oldhamii exhibited the greatest increases in electrolyte leakage (EL) and malondialdehyde (MDA) content. R. simiarum accumulated the highest proline content under stress, while R. latoucheae showed the most significant proline reduction during recovery. By integrating multiple indicators through principal component analysis (PCA) and a membership function, and assigning weights based on variance contribution, the heat tolerance was comprehensively evaluated and ranked as follows: R. latoucheae > R. simiarum > R. oldhamii > R. ovatum > R. fortunei > R. liliiflorum > R. kiangsiense > R. × pulchrum. These findings demonstrate significant differences in heat tolerance among Rhododendron taxa at the subgenus level, with the subgenus Azaleastrum generally possessing stronger short-term heat tolerance compared to the subgenus Tsutsusi. This study provides a theoretical basis for heat-tolerant cultivar breeding and landscape application of Rhododendron.

Root-associated microbiomes vary across environmental settings and root compartments, but these patterns remain poorly understood in wild woody plants. Here, we compared bacterial and fungal communities in the rhizosphere and root endosphere of Rhododendron yunnanense across four montane sampling sites in Yunnan, China, using 16S rRNA gene and internal transcribed spacer (ITS) amplicon sequencing. α-diversity differences were mainly reflected in amplicon sequence variant (ASV) richness, whereas Shannon and Simpson diversity varied less among site–compartment combinations. Bray–Curtis community composition was significantly associated with sampling site, root compartment, and their interaction for both bacteria and fungi. Stable and core ASV analyses further showed limited overlap between the rhizosphere and endosphere. Under the predefined core criteria, only three bacterial ASVs were shared between compartments, while no fungal ASV qualified as a shared core member. The extent of stable-ASV overlap varied among sampling sites and differed between bacterial and fungal communities. Indicator-value analysis, paired abundance testing, and Random Forest classification converged on a smaller set of compartment-associated genera. Thirteen taxonomically interpretable genera were retained for main-text interpretation, including five bacterial genera associated with the endosphere and eight fungal genera, of which Phialocephala was associated with the rhizosphere. Together, these results show that sampling site and root compartment are both associated with marked differentiation of the R. yunnanense root microbiome. The low overlap of stable and core taxa further indicates substantial microbial turnover between the rhizosphere and endosphere, providing a basis for future functional validation of compartment-associated taxa.

Variations in urban surface runoff are often attributed to static infrastructure, neglecting the non-stationary hydrological responses induced by rapid urbanization and intricate micro-topography. This study introduces a Pressure–Trend–Pulse (PTP) framework to examine surface runoff dynamics in Kunming, China. By integrating continuous Soil and Water Assessment Tool (SWAT) simulations (2005–2024), Sen’s slope estimation, the Mann–Kendall test, robust residual analysis, and Self-Organizing Map (SOM) clustering, we quantify these multi-dimensional changes. The findings indicate: (1) runoff displays a structural north–south gradient, with the generation centroid migrating northward at a rate of 2.3 km per decade; (2) non-stationary positive trends (0.16 mm/year) are exclusively concentrated in northern sub-basins, which constitute 26.74% of the total area, thereby exacerbating long-term cumulative pressure; and (3) detrended residual analysis reveals high-frequency pulse volatility predominantly in the southern sink areas. Overlaying 139 historical waterlogging points confirms that trend-driven and pulse-driven risks account for 30.22% and 13.67% of urban disasters, respectively. Furthermore, approximately 22% of waterlogging occurrences fall within non-significant downstream zones, implying a potential upstream-downstream source–sink decoupling. The PTP framework highlights the necessity of differentiated resilience planning: upstream source-control and downstream adaptive buffering.