Dendrobium huoshanense is both a traditional herbal medicine and a plant of high ornamental and medicinal value. We used transcriptomics and metabolomics to investigate the effects of growth year on the secondary metabolites of D. huoshanense stems obtained from four different years of cultivation. In this study, a total of 428 differentially accumulated metabolites (DAMs) and 1802 differentially expressed genes (DEGs) were identified. The KEGG enrichment analysis of DEGs and DAMs revealed significant differences in “Flavonoid biosynthesis”, “Phenylpropanoid biosynthesis” and “Flavone and flavonol biosynthesis”. We summarize the biosynthesis pathway of flavonoids in D. huoshanense, providing new insights into the biosynthesis and regulation mechanisms of flavonoids in D. huoshanense. Additionally, we identified two candidate genes, FLS (LOC110107557) and F3’H (LOC110095936), which are highly involved in flavonoid biosynthesis pathway, by WGCNA analysis. The aim of this study is to investigate the effects of growth year on secondarily metabolites in the plant and provide a theoretical basis for determining a reasonable harvesting period for D. huoshanense.

Dendrobium moniliforme (L.) Sw. is a valuable herbal crop, and flavonoids are primarily distributed as active ingredients in the stem, but the composition and synthesis mechanisms of flavonoids in different growth years are not clear. The accumulation of flavonoids in D. moniliforme from four different years was investigated, using a combined metabolomics and transcriptomics approach in this study. The phenylpropanoid and flavonoid biosynthetic pathways were significantly enriched in the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs). The widely targeted metabolomics technique revealed a total of 173 kinds of flavonoid metabolites. The metabolomics data confirmed the trend of total flavonoids (TF) content in stems of D. moniliforme, with chalcone, naringenin, eriodictyol, dihydroquercetin, and other flavonoids considerably up-accumulating in the third year. Twenty DEGs were detected that regulate flavonoid synthesis and the expression of these genes in different growth years was verified using real-time quantitative PCR (qRT-PCR). Furthermore, a comprehensive regulatory network was built for flavonoid biosynthesis and it was discovered that there is one FLS gene, one CCR gene and two MYB transcription factors (TFs) with a high connection with flavonoid biosynthesis by weighted gene co-expression network analysis (WGCNA). In this study, the correlation between genes involved in flavonoid biosynthesis and metabolites was revealed, and a new regulatory mechanism related to flavonoid biosynthesis in D. moniliforme was proposed. These results provide an important reference for the farmers involved in the cultivation of D. moniliforme.

There is a significant impact of climate change on species distribution and vegetation patterns in high mountain regions, which is a major topic of research in biogeography. It has recently warmed up on the Western Sichuan Plateau, one of the most vulnerable regions to climate change. Based on the MaxEnt model, we were able to predict distributions based on current and future climate conditions, and determine the trend of distribution change and the underlying climate factors. Under current climate conditions, the two typical tree species display distinct spatial distributions. Furthermore, under future climate conditions, distribution ranges of both typical tree species will shrink and move to the northern part of the plateau. The variation in temperature between seasons and years affected the distribution of two tree species. This study provided a scientific basis for understanding how high mountain and plateau forests respond to climate change.

As a global environmental problem, biological invasion poses a serious threat to natural ecosystems. To explore the influence mechanism of Alternanthera philoxeroides (Mart.) Griseb on the growth and development of landscape plants, this study systematically analyzed the effects of extracts from different organs (stems, leaves, and roots) of A. philoxeroides on the seed germination and seedling growth of Zinnia elegans Jacq. by combining the Petri dish filter paper method with a pot experiment to reveal the potential mechanism of allelopathy. The results showed that the aqueous extract of A. philoxeroides inhibited the seed germination and seedling growth of Z. elegans. The high concentration (100 mg·mL⁻¹) of stem and leaf extracts significantly reduced the germination rate (by 99.10% and 90.65%) and seedling morphological parameters. The allelopathic inhibition increased with an increase in concentration, and the inhibitory effect of stem and leaf extracts was significantly stronger than that of root extracts. Aqueous extracts from the roots, stems, and leaves of A. philoxeroides at three concentrations (25, 50, and 100 mg·mL⁻¹) induced oxidative stress in seedlings, as evidenced by the elevated malondialdehyde (MDA) content and dysregulated activities of antioxidant enzymes. Specifically, superoxide dismutase (SOD) and catalase (CAT) activities exhibited a concentration-dependent trend of initial induction followed by subsequent inhibition, while root activity was significantly suppressed (p < 0.05), ultimately impairing seedling growth. The aqueous extracts of A. philoxeroides showed a concentration-dependent inhibitory effect on the seed germination and seedling growth of Z. elegans. High concentrations of stem and leaf extracts exerted a significant inhibitory effect on seedling growth, and this growth suppression was attributed to the induction of oxidative stress by the extracts. This study elucidated the phytotoxicity degree and physiological response mechanisms underlying the biochemical allelopathy of A. philoxeroides on Z. elegans. The findings provide a theoretical foundation for the selection of horticultural plant cultivars resistant to allelopathic stress and the development of management strategies for invasive plants.

Stem development determines plant architecture and mechanical support, directly affecting yield, lodging resistance, and ornamental quality. Microtubules are essential components of the plant cytoskeleton, but their role in stem development in herbaceous peony (Paeonia lactiflora Pall.) remains largely unexplored. Here, a β-tubulin gene, PlTUB1, was identified from P. lactiflora. Its coding sequence was 1353 bp in length, encoding a 450-amino-acid protein that localized to microtubules, and its transcript levels declined progressively during stem development. Transient virus-induced gene silencing of PlTUB1 in P. lactiflora, with a silencing efficiency of approximately 55%, enhanced stem development, with increased stem diameter, elevated cellulose accumulation, and thickened secondary walls. Given that cellulose deposition and secondary wall thickening were closely associated with cortical microtubule organization, the role of PlTUB1 in microtubule regulation was further examined. Heterologous overexpression of PlTUB1 in Arabidopsis thaliana disrupted transverse microtubule alignment, reduced cellulose deposition, and impaired secondary wall and xylem development, thereby confirming the mechanistic link between PlTUB1 and microtubule organization. Collectively, these findings demonstrated that PlTUB1 negatively regulates stem development by modulating microtubule organization and secondary wall deposition, providing new insights into the cytoskeletal regulation of stem development in P. lactiflora.