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Abstract Gentiana macrophylla is one of Chinese herbal medicines in which 4 kinds of iridoids or secoiridoids, such as loganic acid, sweroside, swertiamarin, and gentiopicroside, are identified as the dominant medicinal secondary metabolites. WRKY, as a large family of transcription factors (TFs), plays an important role in the synthesis of secondary metabolites in plants. Therefore, WRKY genes involved in the biosynthesis of secoiridoids in G. macrophylla were systematically studied. First, a comprehensive genome-wide analysis was performed, and 42 GmWRKY genes were identified, which were unevenly distributed in 12 chromosomes. Accordingly, gene structure, collinearity, sequence alignment, phylogenetic, conserved motif and promoter analyses were performed, and the GmWRKY proteins were divided into three subfamilies based on phylogenetic and multiple sequence alignment analyses. Moreover, the enzyme-encoding genes of the secoiridoid biosynthesis pathway and their promoters were then analysed, and the contents of the four secoiridoids were determined in different tissues. Accordingly, correlation analysis was performed using Pearson′s correlation coefficient to construct WRKY gene-enzyme-encoding genes and WRKY gene–metabolite networks. Meanwhile, G. macrophylla seedlings were treated with methyl jasmonate (MeJA) to detect the dynamic change trend of GmWRKYs, biosynthetic genes, and medicinal ingredient accumulation. Thus, a total of 12 GmWRKYs were identified to be involved in the biosynthesis of secoiridoids, of which 8 (GmWRKY1, 6, 12, 17, 33, 34, 38 and 39) were found to regulate the synthesis of gentiopicroside, and 4 (GmWRKY7, 14, 26 and 41) were found to regulate the synthesis of loganic acid. Taken together, this study systematically identified WRKY transcription factors related to the biosynthesis of secoiridoids in G. macrophylla, which could be used as a cue for further investigation of WRKY gene functions in secondary metabolite accumulation.

Global climate change could pose an additional threat to the already vulnerable Gentiana macrophylla. To reduce this emerging climate-related threat, we applied ArcGIS and the maximum entropy method (MaxEnt) to analyse the consequences of climate change on the distribution of G. macrophylla and the vulnerability of this species in China. The modelling results indicate the following: (1) the suitable range of G. macrophylla in China is mainly located in the Loess Plateau hinterland, including the provinces of Shaanxi, Gansu, Shanxi, Ningxia, Hebei and Inner Mongolia, under the current climate conditions; (2) the unsuitable habitats for G. macrophylla in China would increase by 11.92% under the moderate greenhouse gas emissions/climate scenario (RCP4.5) by the 2050s, while significant losses of suitable habitat are predicted to occur; (3) the current suitable habitat mainly located in the Loess Plateau, Great Xingan Mountains, Changbai Mountains and Hengduan Mountains (with a total area of 135.09×104 km2) is predicted to be vulnerable. Climate change will further accelerate the speed of the fragmentation of the vast majority of G. macrophylla suitable habitat, threatening the survival and reproduction of this species in this region. Therefore, some proactive conservation measures should be undertaken to mitigate the adverse effects of climate change. Our findings can be used to provide background information related to the long-term conservation of G. macrophylla.

As a result of the wide distribution of herbal teas the data on nutritional characterisation, chemical profile and biological activity of these products are required. The decoctions of Gentiana algida, G. decumbens, G. macrophylla and G. triflora herb teas were nutritionally characterized with respect to their macronutrients, demonstrating the predominance of polysaccharides and low lipid content. Gentian decoctions were also submitted to a microcolumn RP-HPLC-UV analysis of phytochemicals demonstrating a high content of iridoids (177.18–641.04 μg/mL) and flavonoids (89.15–405.71 μg/mL). Additionally, mangiferin was detected in samples of G. triflora tea (19.89 μg/mL). Five free sugars (fructose, glucose, sucrose, gentiobiose, gentianose) were identified in all gentian teas studied, as well as six organic acids (malic, citric, tartaric, oxalic, succinic, quinic). Pectic polysaccharides with a high content of rhamnogalacturonans and arabinogalactans were also identified and characterized in gentian decoctions for the first time. Gentian tea decoctions and their specific compounds (gentiopicroside, loganic acid-6′-O-β-d-glucoside, isoorientin, isoorientin-4′-O-β-d-glucoside, mangiferin, water-soluble polysaccharides) showed a promising antimicrobial, anti-inflammatory and antioxidant potentials. Evidences obtained indicate the prospective use of gentian herb teas as food products and medicines.

Some Gentiana species have been used by the nomadic people of Siberia as bitter teas or appetizers to eliminate digestive disorders (dyspepsia, heartburn, nausea, etc.). We studied the most frequently used gentians: Gentiana algida, G. decumbens, G. macrophylla and G. triflora. The aim of the present study was to evaluate the phytochemical features and gastrostimulatnt activity of these four gentian herbs. Five iridoids, seven flavones and mangiferin were detected in gentian herbs after analysis by microcolumn-RP-HPLC-UV-ESI-MS. A componential phytochemical profile of the G. decumbens herb is presented for the first time, as well as information about distinct phytochemicals found in gentian herbs. HPLC quantification of the specific compounds of gentian herbs demonstrated the high content of iridoids (24.73–73.53 mg/g) and flavonoids (12.92–78.14 mg/g). The results of biological activity evaluation of four gentian decoctions demonstrated their good ability to stimulate acid-, enzyme- and mucin-forming functions of the stomach attributed to mostly by iridoids and flavonoids. In general, it can be claimed that the gentian decoctions can be used as effective and safe appetizers and are also a good source of biologically active agents.

Gentiana macrophylla is a perennial medicinal plant in the family Gentianaceae. Natural sources for G. macrophylla plants are being exhausted due to over-collection and need urgent conservation. The complete chloroplast DNA sequence of G. macrophylla (GenBank accession number: KY856959) was determined in our study. The size of chloroplast genome of G. macrophylla is 149,916 bp, including a large single-copy (LSC) region of 82,911 bp and a small single-copy (SSC) region of 17,095 bp separated by a pair of identical inverted repeat regions (IRs) of 24,955 bp each. A total of 130 genes were successfully annotated containing 86 protein-coding genes, 36 tRNA genes and 8 rRNA genes. The GC content is 37.7%. 33 chloroplast simple sequence repeats (cpSSRs) of Gentiana macrophylla were detected, in which 32 of them are mononucleotide repeats. Phylogenomic analysis strongly supported the close relationship of G. macrophylla and other 5 species in Gentiana.