The bulbs of the lily plant Fritillaria thunbergii Miq. possess substantial medicinal properties for relieving coughs and clearing the lungs. However, excessive pursuit of yield during cultivation has led to a decrease in medicinal ingredients. Therefore, we aimed to investigate the effects of two single-factor treatments, shading (SK0) and potassium application (S0K), and their coupling treatment (SK) on bulb biomass and medicinal substance content, along with the role of rhizosphere microorganisms. Shading increased the content of active ingredients in bulbs by approximately 11.7% while decreasing bulb biomass by approximately 11.3%. SK treatment mitigated the biomass reduction caused by SK0 treatment while enhancing the accumulation of active ingredients in F. thunbergii, up to 1.2 times higher than that of SK0 treatment. In rhizosphere soil, Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium (ANPR), Chryseobacterium, Brevundimonas, and Phoma exhibited significant positive correlations with medicinal components, among which ANPR, Brevundimonas, Chryseobacterium, and Phoma were responsive to SK treatments. Also, Burkholderia–Caballeronia–Paraburkholderia (BCP) and Brevundimonas responded to changes at different growth stages of F. thunbergii. The relative abundance of these microorganisms was associated with the alterations of soil factors resulting from shading or K application. Our results indicate that these microorganisms are beneficial to the growth of bulbs and the synthesis of active components in F. thunbergii. The combination of shading and K application may regulate the accumulation of medicinal substances in F. thunbergii by modulating the structure of the soil microbial community. Our results serve as a reference for soil improvement for medicinal plant cultivation.

Shade could improve the medicinal quality of Zhebeimu (Fritillaria thunbergii Miq.) bulb, but lead to decreased yield resulting from leaf senescence. Although potassium application can mitigate such yield loss by delaying leaf senescence, the underlying mechanism remains largely unknown. In this two-year field experiment, the widely cultivated variety 'Zhebei 3' was subjected to shade (around 50% shading) from the squaring stage, along with potassium application of 22.5 kg K₂O ha^-1. Shade treatment elevated the levels of senescence-inducing phytohormones [abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), and 1-aminocyclopropanecarboxylic acid (ACC, the direct precursor of ethylene)], and reduced anti-senescence phytohormones [auxin (IAA) and cytokinin (CTK)]. It also suppressed the active oxygen scavenging system by lowering the activities of antioxidant enzymes [superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and glutathione peroxidase (GPX)] and the concentrations of non-enzymatic antioxidants [phenolics, flavonoids, flavones, and ascorbic acid (AsA)], leading to increased accumulation of O₂^- and malondialdehyde (MDA). Furthermore, shade impaired nitrogen assimilation via inhibiting the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT), thereby decreasing amino acid and soluble protein contents. These combined effects resulted in reduced chlorophyll contents and early leaf senescence. By contrast, potassium application increased IAA and CTK levels, enhanced activities of antioxidant enzymes (SOD, POD, CAT, and GPX) and contents of non-enzymatic antioxidant including flavonoids [(+)-gallocatechin, aromadendrin, kaempferol, quercetin, and myricetin] and flavones (kaempferol 3-sophorotrioside, astragalin, rutin, nictoflorin, quercetin 3-sophorotrioside, and isoquercitrin), and improved nitrogen assimilation. These changes collectively elevated chlorophyll contents and delayed shade-induced leaf senescence. Overall, this study broadened the understanding of the mechanism of potassium application in alleviating leaf senescence under shade.

Fritillaria thunbergii Miq., a medicinal plant rich in steroidal alkaloids, produces bulbs that clear heat, resolve phlegm, and detoxify. However, excessive yield-oriented cultivation has reduced the number of F. thunbergii plants that meet commercial standards. This study explored the effects of potassium application and shading on the bulb biomass and medicinal substance content of F. thunbergii. Shading increased the active ingredient content in bulbs by approximately 20.71% but reduced biomass by approximately 17.24%. Fertilization with different potassium concentrations under shading (K1S–K3S) alleviated shading-induced biomass reduction and increased active ingredient accumulation, with the K2S and K3S groups yielding significantly better results than the K1S group. Pharmacological experiments showed that the K2S group exerted the best antitussive, expectorant, and anti-inflammatory effects. Metabolome analysis showed that compared with those in the controls, peiminine, peimine, imperialine, solasodine, and cyclopamine were the most abundant steroidal alkaloids under K2S treatment. Transcriptome analysis identified key genes and biosynthetic pathways for major steroidal alkaloids, namely, farnesyl pyrophosphate synthase (FtFPS) involved in steroidal alkaloid biosynthesis. Transcription factor analysis revealed that nine transcription factors predominantly expressed under the K2S treatment might regulate steroidal alkaloid biosynthesis. Furthermore, FtFPS was identified as a hub gene in the co-expression network and was verified to catalyze the biosynthesis of farnesyl pyrophosphate. The interaction between FtFPS and FtAP2/ERF was verified through yeast two-hybrid experiments. These findings offer new insights into the steroidal alkaloid biosynthesis mechanism triggered in F. thunbergii by potassium application and shading, supporting ecological strategies to enhance steroidal alkaloid levels in this species.

The secondary metabolites in the bulbs of Fritillaria species display distinct spatial distribution patterns, yet the underlying mechanisms remain unclear. In this study, bulbs of Fritillaria thunbergii were divided into inside (IS) and outside (OS) layers. Integrated physiological, transcriptomic, metabolomic, and microbiomic analyses were performed to elucidate the spatial regulation of alkaloids, flavonoids, and carbohydrates. The OS was significantly enriched in secondary metabolites, with total alkaloid, peimine, and total flavonoid contents being approximately 1.18-, 1.28-, and 1.24-fold higher, respectively, than those in the IS. In contrast, carbohydrates mainly accumulated in the IS, where sucrose and starch levels were 1.37- and 2.18-fold higher than those in the OS. Transcriptomic analysis revealed that carbohydrate enrichment in the IS was associated with the upregulation of sucrose synthase (SUS) and hexokinase (HK) genes, and the downregulation of β-amylase3 (BAM3) and invertase (INV). In the OS, genes related to steroidal alkaloid biosynthesis, including 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS), 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), and farnesyl-diphosphate farnesyltransferase 1 (FDFT1), as well as flavonoid biosynthesis genes phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), and cytochrome P450 monooxygenase CYP75B1 (CYP75B1), were upregulated. Moreover, bacterial taxa enriched in the OS, such as Actinomycetota and Ruminococcus, correlated positively with alkaloid accumulation, while the fungal genus Aspergillus was potentially associated with flavonoid regulation. Overall, the multi-omics insights provided here not only offer theoretical support for refined, region-specific processing of Zhejiang Fritillaria bulbs but also open new avenues to improve medicinal quality by manipulating host gene expression and microbial community composition.

The global demand for Salvia miltiorrhiza Bunge in the botanical medicine market is steadily increasing. However, its production has long relied on asexual root propagation, making it highly susceptible to germplasm degradation. Transitioning to seed reproduction offers the advantage of genetic renewal, yet it is constrained by unstable seed vigor and slow seedling growth. In the present study, comprehensive physiological and microbiome analyses of S. miltiorrhiza seeds from 14 regions across 7 provinces in China were conducted to elucidate the association between the seed microbiome and vigor, and to identify plant growth-promoting (PGP) strains. The results demonstrated: (1) Seed physical traits and germination characteristics varied significantly across geographic origins. Seed vigor, exhibiting the highest coefficient of variation, served as a key parameter reflecting germination quality. (2) High-vigor seeds harbored distinct microbial communities characterized by higher diversity indices, greater network complexity, and the significant enrichment of potentially beneficial bacteria (e.g., Pseudomonas). (3) Through correlation-directed screening of isolated pure cultures, Pseudomonas mendocina P-6 and Enterobacter ludwigii BM-12 were identified as exhibiting robust, multi-trait PGP capacity. In planta validation showed that these two strains significantly promoted the growth of 1-month-old S. miltiorrhiza seedlings, increasing total fresh weight by 33.9–71.3%. This study reveals the microecological drivers of seed vigor and provides candidate strains for inoculant development, thereby supporting the sustainable, seed-based propagation of S. miltiorrhiza.