Systematic screening and analysis of bZIP transcription factors in Glycyrrhiza uralensis and their response to ABA stress / 药学学报

Licorice, one of the most commonly used medicinal materials in China, grows mainly in arid and semi-arid regions and has important economic and ecological values. Basic leucine zipper (bZIP) transcription factors in plants play an important role in regulating biological or abiotic stress responses, growth, and secondary metabolite synthesis. bZIP transcription factors in the published whole genome database of Glycyrrhiza uralensis were identified using bZIP sequences found in Arabidopsis thaliana genome as reference, and ABA-dependent bZIP genes were identified by using Illumina high-throughput sequencing. The physical and chemical properties, structure of the encoded proteins, and the gene expression patterns with exogenous ABA stress were analyzed. A total of 69 bZIP transcription factor genes were identified in G. uralensis, named Gubzip1-69, and they were divided into 10 subfamilies (A-I and S) according to their similarity to bZIPs of A. thaliana. By calculating the relative expression levels of the 69 GubZIPs genes under different concentrations of exogenous ABA stress, genes that may be involved in the regulation of ABA signaling pathways were identified, namely GubZIP1, GubZIP5, GubZIP8, GubZIP30, GubZIP33 and GubZIP56. The results of expression pattern analysis of these GubZIPs genes under exogenous ABA stress showed that the expression pattern of GubZIPs genes changed significantly with 50 mg·L-1 ABA. The relative expression levels of these genes decreased 3 h after treatment, and gradually increased 6 h after treatment. Except for GubZIP8, the relative expression levels of these genes were significantly increased after 12 h. Further research on the function of bZIP transcription factors of G. uralensis and elucidating their regulatory mechanisms should be of interest and will provide a scientific basis for cultivating high-quality cultivars of G. uralensis through molecular breeding methods.

Overexpression of (3S)-linalool synthase gene (LIS) regulates the glycyrrhizic acid biosynthesis in Glycyrrhiza uralensis hairy roots / 药学学报

(3S)-Linalool synthase (LIS) is a key enzyme involved in the monoterpene biosynthetic pathway. Based on our previous transcriptome study, the expression level of LIS gene was exceedingly related to glycyrrhizic acid (GA) biosynthesis. Therefore, we used hairy root culturing to further investigate the effect of LIS on the GA biosynthesis. A LIS gene (GenBank accession number: MZ169552) was cloned from Glycyrrhiza uralensis. The plant binary overexpression vector pCA-LIS was constructed by gene fusion. G. uralensis hairy roots overexpressing LIS were induced by the Agrobacterium rhizogenes ATCC15834. The expression levels of LIS were analyzed by real-time quantitative PCR (RT-qPCR) and the contents of GA in hairy root lines were determined by UPLC. It was found that in the hairy root lines overexpressing LIS, the expression levels of LIS were significantly higher than that in the wild type, while the contents of GA were remarkably lower than those in the wild type and negative control. These findings indicate that the expression level of LIS is negatively correlated with the accumulation of GA. In this study, LIS was cloned from G. uralensis for the first time and the negative regulatory effect of LIS on GA biosynthesis was confirmed by reverse genetics. This work provides support for further improvement of the molecular regulatory network of GA biosynthesis in G. uralensis.

Metabolomic investigation of secondary metabolites of prepared slices of Glycyrrhiza uralensis with different degrees of honey processing / 药学学报

A metabolomics method was used to search for chemical markers in prepared slices of Glycyrrhiza uralensis with different degrees of honey processing. Coupled with these metabolomics analytical methods, ultra-performance liquid chromatography with quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF/MS) was used to generate global chemical profiles of the raw material of Glycyrrhiza uralensis and the prepared slices. The samples were collected in Shanxi, Hebei Zhangjiakou and Inner Mongolia. A total of 57 chemical components were identified in Glycyrrhiza uralensis by using the UNIFI theoretical database combined with the library of reference samples. Among them, 37 compounds were identified in positive ion mode and 56 compounds were identified in negative ion mode. Unsupervised principal component analysis (PCA) showed that the chemical ingredients differed considerably depending on the extent of processing. Supervised orthogonal partial least squares discriminant analysis (OPLS-DA) was used to differentiate the moderate processing group and the raw group, and partial least squares discriminant analysis (PLS-DA) was used to differentiate the less, the moderate, and the excessive processing groups. The results showed that the contents of glycyrrhizic acid, licoricesaponin G2, and licoricesaponin E2 varied with the extent of processing. The content of these components increased after processing, and reached the highest level when the extent of processing was moderate (P < 0.05). Glycyrrhizic acid, licoricesaponin G2 and licoricesaponin E2 can be regarded as the chemical markers to differentiate the samples with different degrees of processing. These three compounds can be used to monitor the processing of Glycyrrhiza uralensis.

Based on weak bond chemistry, the interaction mechanism between glycyrrhiza protein and berberine in water decocting process of Rhizoma Coptidis and Liquorice was investigated / 药学学报

The purpose of this study was to explore the interaction mechanism between glycyrrhiza protein and berberine in the decocting process of Rhizoma Coptidis and Liquorice and its effect on the pharmacodynamic effect. In this experiment, licorice crude protein was obtained from licorice decoction pieces, and it was found that licorice crude protein and berberine could form spherical supramolecular particles after decocting together. Morphological characterization was carried out by using Malvin particle size analyzer and emission scanning electron microscopy, and the supramolecular particles were observed to be nanoscale, which was significantly different from the morphology of licorice protein and berberine. The results of ultraviolet, infrared and fluorescence spectroscopy showed that the mechanism of molecular interaction was induced by weak bonds such as electrostatic attraction and hydrophobic interaction. Furthermore, the antimicrobial activity of berberine was significantly affected by the supramolecular particles of licorice protein-berberine, which were significantly different from the mechanical mixture. This study reveals the pharmacological value of macromolecular substances such as proteins in the decoction of licorice and Coptis chinensis from a new perspective, which is helpful to promote the secondary development of clinical effective prescriptions, especially the research on the pharmacological substance basis of classic famous prescriptions.

Overexpressing of chalcone isomerase (CHI) gene enhances flavonoid accumulation in Glycyrrhiza uralensis hairy roots / 药学学报

Chalcone isomerase (CHI) is the second rate-limiting enzyme involved in the biosynthetic pathway of flavonoids in Glycyrrhiza uralensis. Based on our previous studies, we selected the specific CHI haplotype (GenBank Accession No. KY115232) to maximize flavonoid accumulation. We constructed a plant binary expression vector for overexpression of this CHI gene by the gene fusion method and transfected the plasmid into Agrobacterium tumefaciens ACCC10060 by electroporation. The recombinant A. tumefaciens ACCC10060 subsequently was used to infect cotyledons and hypocotyls of G. uralensis to obtain transgenic hairy roots. A qRT-PCR method was used to determine the copy number of CHI and a UPLC method was used to assay the content of four flavonoids in different hairy root lines. The qRT-PCR results showed that the copy number of CHI in hairy roots was 1 or 5. UPLC results showed that the content of total flavonoids, liquiritin, liquiritigenin, and isoliquiritigenin in transgenic hairy root samples was significantly higher than that in wild-type samples. This study demonstrates that overexpression of CHI significantly increases the content of flavonoids in hairy roots of G. uralensis. This work provides a theoretical basis for clarifying the function of CHI. Three transgenic hairy root lines of G. uralensis were isolated which can be used to increase the accumulation of licorice flavonoids in vitro.

Diversity and isolation parameters of endophytes from Glycyrrhiza uralensis of different habitats / 药学学报

In order to determine the differences in structure and optimum isolation conditions of Glycyrrhiza uralensis endophytes from different habitats, plate-separation method was used to identify endophytes in G. uralensis from Gansu, Ningxia, Inner Mongolia, Xinjiang, and Beijing. The isolation parameters were defined by investigating various concentrations and sterilization time of NaClO solution. The strains were identified by morphological and molecular biological methods. The results showed that 5% NaClO solution and sterilization time of 5 min were the optimal surface sterilization conditions. Among 129 strains of G. uralensis from 5 producing areas, 438 strains of endophytic fungi were isolated and belonged to 5 orders, 7 genera, and 11 species. Among them, 4 taxa were firstly isolated from the licorice in China. Fusarium was a common genus among the 5 regions. There were differences in the composition and structure of the endophytic fungi of G. uralensis from different habitats. Diversity analysis showed that the endophytic fungi diversity in Gansu was the highest and that of Beijing was the lowest. The comprehensive analyses indicated that the endophytic fungi of G. uralensis are diverse, and there were differences among the number, composition and population of endophytic fungi in five producing areas of Gansu, Ningxia, Inner Mongolia, Xinjiang and Beijing.