Search Results (3)

Mirabilis himalaica is an endemic Tibetan medicinal plant distributed from the Western Himalaya to the Hengduan Mountains, highly regarded for its abundant flavonoids. Traditional knowledge holds that its medicinal properties vary considerably with geographic origin, yet the genetic and metabolic basis of this differentiation remains poorly understood. Here, we integrated plastome resequencing of 134 individuals from 23 populations with metabolomic and transcriptomic analyses of three representative sites to investigate population genetic variation and flavonoid metabolic differentiation. Pan-plastome revealed a typical quadripartite structure (154,232–154,422 bp) containing 113 unique genes across M. himalaica. A total of 620 SNVs, 171 indels, and four small inversions were identified from the pan-plastome, and further analyses based on these variants supported the delineation of four genetic lineages across all individuals. Overall genetic diversity was high (H_T = 0.985, H_S = 0.580), with majority variation occurring among groups (71.038%). Both IBD and IBE analyses found a significantly positive correlation between genetic distance and geographic and environmental distance (IBD: r = 0.348, p = 0.001; IBE: r = 0.219, p = 0.016). Flavonoids represented the most abundant metabolites (19.5%) and showed significantly higher accumulation in high-altitude populations, where key biosynthetic genes (e.g., CHS) were upregulated. Notably, these altitude-associated metabolic patterns were observed independently of the plastome-based genetic lineages. Together, we propose defining four evolutionary lineages as conservation units and prioritizing populations with unique haplotypes. This study provides critical genomic resources for provenance tracing, quality evaluation, and conservation management of this endangered Tibetan medicinal plant, and offers preliminary insights into the parallel patterns of pan-plastome variation and altitude-related metabolic differentiation, though without evidencing a direct causal link between them. Full article

Background: Mirabilis himalaica, distributed in the high-altitude, arid, and semi-arid regions of Xizang, exhibits great tolerance to drought, which is rich in rotenoids and other secondary metabolites. It is still unknown, though, how drought stress influences rotenoid synthesis in M. himalaica. Methods: In this study, the calli of M. himalaica were subjected to 5% PEG6000 for 0, 20, and 40 h and divided into control group (CK), mild-drought-treated group (M), and high-drought-treated group (H), respectively. We then analyzed the relative content of three main rotenoids in M. himalaica using high-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (HPLC-ESI-MS/MS). Results: Our findings demonstrated that the content of rotenoids was significantly reduced under drought stress. Transcriptome analysis subsequently revealed 14,525 differentially expressed genes (DEGs) between the different treatments. Furthermore, these DEGs exhibited enrichment in pathways associated with isoflavone biosynthesis and hormone signaling pathways. Key genes with decreased expression patterns during drought stress were also found to be involved in rotenoid accumulation and drought-responsive phytohormone signaling, including abscisic acid (ABA), auxin (IAA), and jasmonic acid (JA). Conclusions: These findings elucidate the molecular processes of drought resistance in M. himalaica and shed light on the relationship between rotenoid production and drought stress in M. himalaica. Full article

Mirabilis himalaica (Edgew.) Heimerl is one of the most important genuine medicinal plants in Tibet, in which the special plateau habitat has been associated with its excellent medicinal quality and efficacy. However, the mechanisms by which environmental factors affect biosynthesis of secondary metabolic components remain unclear in this species. In this study, RNA sequencing and iTRAQ (isobaric Tags for Relative and Absolute Quantification) techniques were used to investigate the critical molecular “events” of rotenoid biosynthesis responding to UV-B radiation, a typical plateau ecological factor presented in native environment-grown M. himalaica plants. A total of 3641 differentially expressed genes (DEGs) and 106 differentially expressed proteins (DEPs) were identified in M. himalaica between UV-B treatment and control check (CK). Comprehensive analysis of protein and transcript data sets resulted in 14 and 7 DEGs from the plant hormone signal transduction and phosphatidylinositol signaling system pathways, respectively, being significantly enriched. The result showed that the plant hormone signal transduction and phosphatidylinositol signaling system might be the key metabolic strategy of UV-B radiation to improve the biosynthesis of rotenoid in M. himalaica. At same time, most of the DEGs were associated with auxin and calcium signaling, inferring that they might drive the downstream transmission of these signal transduction pathways. Regarding those pathways, two chalcone synthase enzymes, which play key roles in the biosynthesis of rotenoid that were thought as the representative medicinal component of M. himalaica, were significantly upregulated in UV-B radiation. This study provides a theoretical basis for further exploration of the adaptation mechanism of M. himalaica to UV-B radiation, and references for cultivation standardization. Full article