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.

Rhododendron delavayi Franch. predominantly thrives in broad-leaved evergreen forests and bushes at altitudes of 1,200–3,200 meters. It favors a cool, moist climate and thrives in acidic soils. Due to its high ornamental, medicinal, and scientific values, understanding its ecological needs and optimal cultivation ranges is crucial. This study analyzing the key environmental factors and their thresholds affecting its distribution and predicts the future potential habitats of R. delavayi using existing distribution data alongside current and projected climate data. The results indicate that the primary environmental influencers are soil pH (4.9–5.4), precipitation in the driest month (10–20 mm), and altitude, contributing 41.8, 24.1, and 18.3%, respectively. It also shows a declining trend in suitable habitats: from 27.75 × 10⁴ km² under current conditions, to 3.69 × 10⁴ km² by the 2050s, and further to 2.65 × 10⁴ km² by the 2070s.

Background: The bHLH genes play a crucial role in plant growth, development, and stress responses. However, there is currently limited research on bHLH genes in the important horticultural plant Rhododendron delavayi Franch. Methods: In this study, we conducted a comprehensive genome-wide identification and in-depth analysis of the bHLH gene family in R. delavayi using bioinformatics approaches. Results: A total of 145 bHLH family members were identified, encoding proteins ranging from 98 to 3300 amino acids in length, with molecular weights ranging from 11.44 to 370.51 kDa and isoelectric points ranging from 4.22 to 10.80. These 145 bHLH genes were unevenly distributed across 13 chromosomes, with three bHLH genes located on contig 52. Chromosome 8 contained the highest number of bHLH family members with 19 genes, while chromosomes 9 and 13 had the lowest, with 7 genes each. Phylogenetic analysis revealed a close evolutionary relationship between bHLH genes in R. delavayi and Arabidopsis thaliana. Subcellular localization analysis indicated that most bHLH genes were located in the nucleus. Promoter analysis of R. delavayi bHLH genes revealed the presence of various cis-regulatory elements associated with light responses, methyl jasmonate responses, low-temperature responses, and coenzyme responses, suggesting that bHLH genes are involved in multiple biological processes in R. delavayi. Through transcriptome analysis, we identified three key functional genes—Rhdel02G0041700, Rhdel03G0013600, and Rhdel03G0341200—that may regulate flower color in R. delavayi. Conclusions: In conclusion, our study comprehensively identified and analyzed the bHLH gene family in R. delavayi and identified three bHLH genes related to flower color, providing a foundation for molecular biology research and breeding in R. delavayi.

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.

Ecosystem services are pivotal in assessing environmental health and societal well-being. Focusing on Lake Dianchi Basin (LDB), China, our research evaluated the IESV (Integrated Ecosystem Service Value) from 2000 to 2020, utilizing remote sensing and multiple statistical datasets. The analysis incorporates LSV (Landscape Service Value), CSV (Carbon Sequestration Value), and NPPV (Net Primary Productivity Value). The results show that LSV and CSV exhibited an expansion of low-yield zones near urban areas, contrasted by NPPV’s growth in high-yield outskirt areas. LSV’s normal distribution indicates stability, while CSV’s bimodal structure points to partial integration and systemic divergence. IESV pronounced clustering in both low- and high-yield regions, with low-yield zones congregating near urban centers and high-yield zones dispersed along the basin’s periphery. Despite an overall downward trajectory in IESV, NPPV’s augmentation suggested an underlying systemic resilience. A southeastward shift in IESV’s focus was driven by patterns of urban expansion. Finally, we produced projections with the CA-MC (Cellular Automata–Markov Chain) model to analyze the ongoing distribution of IESV areas around Kunming. By 2030, IESV’s aggregate value is expected to modestly diminish, with NPPV’s ascension mitigating the declines in LSV and CSV. In essence, IESV fluctuations within the LDB are intricately linked to urban development.