Molecular cloning and functional characterization of UGTs from Glycyrrhiza uralensis flavonoid pathway.

Glycyrrhiza uralensis Fisch., a well-known medicinal plant, contains flavonoids including liquiritigenin and isoliquiritigenin, and their corresponding glycoside liquiritin and isoliquiritin. Although some genes encoding UDP-glycosyltransferases (UGTs) have been functionally characterized in G. uralensis, other UGTs mechanisms of glycosylation remain to be elucidated. Against this background the aim of the present study included cloning and characterization of two full-length cDNA clones of GuUGT isoforms from the UGT multigene family. These included GuUGT2 (NCBI acc. MK341791) and GuUGT3 (NCBI acc. MK341793) with an ORF of 1473 and 1332 bp, respectively. Multiple alignments and phylogenetic analysis revealed GuUGTs protein of Glycine max had a high homology to that of other plants. Meanwhile, quantitative real-time PCR was performed to detect the transcript levels of GuUGTs in different tissues. The results indicated that GuUGTs was more expressed in roots as compared to the leaves, and significantly up-regulated upon NaCl stress. The recombinant protein was heterologous expressed in Escherichia coli and exhibited a high level of UGT activity, catalyzing formation of isoliquiritin and liquiritin from isoliquiritigenin and liquiritigenin. The key residues of GuUGT2 for liquiritigenin glycosylation (Asn223), isoliquiritigenin (Asp272) were predicted by molecular docking and residue scanning based on simulated mutations. These results could serve as an important reference to understand the function of the UGT family. In addition, the identification of GuUGT2 and GuUGT3 provides a foundation for future studies of flavonoid biosynthesis in G. uralensis.

Mining of UDP-glucosyltrfansferases in licorice for controllable glycosylation of pentacyclic triterpenoids.

Pentacyclic triterpenoids have wide applications in the pharmaceutical industry. The precise glucosylation at C-3 OH of pentacyclic triterpenoids mediated by uridine 5'-diphospho-glucosyltransferase (UDP-glucosyltransferase [UGT]) is an important way to produce valuable derivatives with various improved functions. However, most reported UGTs suffer from low regiospecificity toward the OH and COOH groups of pentacyclic triterpenoids, which significantly decreases the reaction efficiency. Here, two new UGTs (UGT73C33 and UGT73F24) were discovered in Glycyrrhiza uralensis. UGT73C33 showed high activity but poor regioselectivity toward the C-3 OH and C-30 COOH of pentacyclic triterpenoid, producing three glucosides. UGT73F24 showed rigid regioselectivity toward C-3 OH of typical pentacyclic triterpenoids producing only C-3 O-glucosylated derivatives. In addition, UGT73C33 and UGT73F24 showed a broad substrate scope toward typical flavonoids with various sugar donors. Next, the substrate recognition mechanism of UGT73F24 toward glycyrrhetinic acid (GA) and UDP-glucose was investigated. Two key residues, I23 and L84, were identified to determine activity, and site-directed mutagenesis of UGT73F24-I23G/L84N increased the activity by 4.1-fold. Furthermore, three in vitro GA glycosylation systems with UDP-recycling were constructed, and high yields of GA-3-O-Glc (1.25 mM), GA-30-O-Glc (0.61 mM), and GA-di-Glc (0.26 mM) were obtained. The de novo biosynthesis of GA-3-O-glucose (26.31 mg/L) was also obtained in engineered yeast.

Mining of Sucrose Synthases from Glycyrrhiza uralensis and Their Application in the Construction of an Efficient UDP-Recycling System.

Sucrose synthase (SUS) plays an important role in carbohydrate metabolism in plants. The SUS genes in licorice remain unknown. To reveal the sucrose metabolic pathway in licorice, all the 12 putative SUS genes of Glycyrrhiza uralensis were systematically identified by genome mining, and two novel SUSs (GuSUS1 and GuSUS2) were isolated and characterized for the first time. Furthermore, we found that the flexible N-terminus was responsible for the low stability of plant SUSs, and deletion of redundant N-terminus improved the stability of GuSUS1 and GuSUS2. The half-life of both GuSUS1 and GuSUS2 mutants was increased by 2-fold. Finally, the GuSUS1 mutant was coupled with UGT73C11 for the glycosylation of glycyrrhetinic acid (GA) with uridine 5'-diphosphate disodium salt hydrate (UDP) in situ recycling, and GA conversion was increased by 7-fold. Our study not only identified the SUS genes in licorice but also provided a stable SUS mutant for the construction of an efficient UDP-recycling system for GA glycosylation.

[Study of heterologous efficient synthesis of ß-amyrin and high-density fermentation].

In this study, the synthetic pathway of ß-amyrin was constructed in the pre-constructed Saccharomyces cerevisiae chassis strain Y0 by introducing ß-amyrin synthase from Glycyrrhiza uralensis, resulting strain Y1-C20-6, which successfully produced ß-amyrin up to 5.97 mg·L~(-1). Then, the mevalonate pyrophosphate decarboxylase gene(ERG19), mevalonate kinase gene(ERG12), 3-hydroxy-3-methylglutaryl-CoA synthase gene(ERG13), phosphomevalonate kinase gene(ERG8) and IPP isomerase gene(IDI1)were overexpressed to promoted the metabolic fluxto the direction of ß-amyrin synthesis for further improving ß-amyrin production, resulting the strain Y2-C2-4 which produced ß-amyrin of 10.3 mg·L~(-1)under the shake flask fermentation condition. This is 100% higher than that of strain Y1-C20-6, illustrating the positive effect of the metabolic engineering strategy applied in this study. The titer of ß-amyrin was further improved up to 157.4 mg·L~(-1) in the fed-batch fermentation, which was almost 26 fold of that produced by strain Y1-C20-6. This study not only laid the foundation for the biosynthesis of ß-amyrin but also provided a favorable chassis strain for elucidation of cytochrome oxidases and glycosyltransferases of ß-amyrin-based triterpenoids.

Functional specialization of UDP-glycosyltransferase 73P12 in licorice to produce a sweet triterpenoid saponin, glycyrrhizin.

Glycyrrhizin, a sweet triterpenoid saponin found in the roots and stolons of Glycyrrhiza species (licorice), is an important active ingredient in traditional herbal medicine. We previously identified two cytochrome P450 monooxygenases, CYP88D6 and CYP72A154, that produce an aglycone of glycyrrhizin, glycyrrhetinic acid, in Glycyrrhiza uralensis. The sugar moiety of glycyrrhizin, which is composed of two glucuronic acids, makes it sweet and reduces its side-effects. Here, we report that UDP-glycosyltransferase (UGT) 73P12 catalyzes the second glucuronosylation as the final step of glycyrrhizin biosynthesis in G. uralensis; the UGT73P12 produced glycyrrhizin by transferring a glucuronosyl moiety of UDP-glucuronic acid to glycyrrhetinic acid 3-O-monoglucuronide. We also obtained a natural variant of UGT73P12 from a glycyrrhizin-deficient (83-555) strain of G. uralensis. The natural variant showed loss of specificity for UDP-glucuronic acid and resulted in the production of an alternative saponin, glucoglycyrrhizin. These results are consistent with the chemical phenotype of the 83-555 strain, and suggest the contribution of UGT73P12 to glycyrrhizin biosynthesis in planta. Furthermore, we identified Arg32 as the essential residue of UGT73P12 that provides high specificity for UDP-glucuronic acid. These results strongly suggest the existence of an electrostatic interaction between the positively charged Arg32 and the negatively charged carboxy group of UDP-glucuronic acid. The functional arginine residue and resultant specificity for UDP-glucuronic acid are unique to UGT73P12 in the UGT73P subfamily. Our findings demonstrate the functional specialization of UGT73P12 for glycyrrhizin biosynthesis during divergent evolution, and provide mechanistic insights into UDP-sugar selectivity for the rational engineering of sweet triterpenoid saponins.

UGT73F17, a new glycosyltransferase from Glycyrrhiza uralensis, catalyzes the regiospecific glycosylation of pentacyclic triterpenoids.

The regiospecific glycosylation of pentacyclic triterpenoids by UGT73F17, a new glycosyltransferase from Glycyrrhiza uralensis, is highlighted. UGT73F17 exhibited strict substrate specificity toward the carboxyl group at C-30/C-29 of pentacyclic triterpenoids, and showed high promiscuity to sugar donors. UGT73F17 represents the first identified triterpenoid 30/29-O-glycosyltransferase, and could be used as an effective biocatalyst to synthesize glycosyl ester saponins.

Silicon alleviates salt and drought stress of Glycyrrhiza uralensis seedling by altering antioxidant metabolism and osmotic adjustment.

This study was conducted to determine effect and mechanism of exogenous silicon (Si) on salt and drought tolerance of Glycyrrhiza uralensis seedling by focusing on the pathways of antioxidant defense and osmotic adjustment. Seedling growth, lipid peroxidation, antioxidant metabolism, osmolytes concentration and Si content of G. uralensis seedlings were analyzed under control, salt and drought stress [100 mM NaCl with 0, 10 and 20% of PEG-6000 (Polyethylene glycol-6000)] with or without 1 mM Si. Si addition markedly affected the G. uralensis growth in a combined dose of NaCl and PEG dependent manner. In brief, Si addition improved germination rate, germination index, seedling vitality index and biomass under control and NaCl; Si also increased radicle length under control, NaCl and NaCl-10% PEG, decreased radicle length, seedling vitality index and germination parameters under NaCl-20% PEG. The salt and drought stress-induced-oxidative stress was modulated by Si application. Generally, Si application increased catalase (CAT) activity under control and NaCl-10% PEG, ascorbate peroxidase (APX) activity under all treatments and glutathione (GSH) content under salt combined drought stress as compared with non-Si treatments, which resisted to the increase of superoxide radicals and hydrogen peroxide caused by salt and drought stress and further decreased membrane permeability and malondialdehyde (MDA) concentration. Si application also increased proline concentration under NaCl and NaCl-20% PEG, but decreased it under NaCl-10% PEG, indicating proline play an important role in G. uralensis seedling response to osmotic stress. In conclusion, Si could ameliorate adverse effects of salt and drought stress on G. uralensis likely by reducing oxidative stress and osmotic stress, and the oxidative stress was regulated through enhancing of antioxidants (mainly CAT, APX and GSH) and osmotic stress was regulated by proline.

CYP716A179 functions as a triterpene C-28 oxidase in tissue-cultured stolons of Glycyrrhiza uralensis.

KEY MESSAGE: CYP716A179, a cytochrome P450 monooxygenase expressed predominantly in tissue-cultured stolons of licorice ( Glycyrrhiza uralensis ), functions as a triterpene C-28 oxidase in the biosynthesis of oleanolic acid and betulinic acid. Cytochrome P450 monooxygenases (P450s) play key roles in the structural diversification of plant triterpenoids. Among these, the CYP716A subfamily, which functions mainly as a triterpene C-28 oxidase, is common in plants. Licorice (Glycyrrhiza uralensis) produces bioactive triterpenoids, such as glycyrrhizin and soyasaponins, and relevant P450s (CYP88D6, CYP72A154, and CYP93E3) have been identified; however, no CYP716A subfamily P450 has been isolated. Here, we identify CYP716A179, which functions as a triterpene C-28 oxidase, by RNA sequencing analysis of tissue-cultured stolons of G. uralensis. Heterologous expression of CYP716A179 in engineered yeast strains confirmed the production of oleanolic acid, ursolic acid, and betulinic acid from ß-amyrin, α-amyrin, and lupeol, respectively. The transcript level of CYP716A179 was about 500 times higher in tissue-cultured stolons than in intact roots. Oleanolic acid and betulinic acid were consistently detected only in tissue-cultured stolons. The discovery of CYP716A179 helps increase our understanding of the mechanisms of tissue-type-dependent triterpenoid metabolism in licorice and provides an additional target gene for pathway engineering to increase the production of glycyrrhizin in licorice tissue cultures by disrupting competing pathways.

[Mechanism of genuineness of Glycyrrhiza uralensis based on SNP of ß-Amyrin synthase gene].

ß-Amyrin synthase (ß-AS) genes of Glycyrrhiza uralensis from 6 different regions were analyzed by PCR-SSCP and sequenced, then the correlationship between ß-AS SNP and regions of Glycyrrhiza uralensis were determined. According to the 1 coding single nucleotide polymorphism on the first exon of ß-AS gene at 94 bp site, Glycyrrhiza uralensis could be divided into 3 genotypes. In these genotypes, the percentage of 94A type in genuine regions was much higher, and it had significant differences with the percentage in non-genuine regions (P < 0.001). The results of the experiment proved that different ß-AS genotypes at 94 bp site from different regions may be one of the important reasons to result in the genuineness of Glycyrrhiza uralensis.

GuA6DT, a regiospecific prenyltransferase from Glycyrrhiza uralensis, catalyzes the 6-prenylation of flavones.

GuA6DT, a flavonoid prenyltransferase, was identified from Glycyrrhiza uralensis, and it was found that this enzyme regiospecifically transfers a dimethylallyl moiety to apigenin at the C-6 position. A further substrate specificity investigation indicated that the existence of hydroxyls at both the C-5 and C-7 positions of the flavone skeleton is critical for the prenylation. However, substitutions on the B-ring had negligible influence on the prenylation. A comparison of GuA6DT expression in different organs revealed that mRNA is mainly expressed in the aerial parts. Moreover, the GuA6DT mRNA was found to be regulated at the transcriptional level, because methyl jasmonate induced upregulation in cultured cells. GuA6DT is the first identified flavone prenyltransferase to exhibit strict substrate specificity and regiospecificity.

Cloning and characterization of a cDNA coding 3-hydroxy-3-methylglutary CoA reductase involved in glycyrrhizic acid biosynthesis in Glycyrrhiza uralensis.

The roots of Glycyrrhiza uralensis are widely used in Chinese medicine for their action of clearing heat, detoxicating, relieving cough, dispelling sputum and tonifying spleen and stomach. The reason why Glycyrrhiza uralensis has potent and significant actions is that it contains various active secondary metabolites, especially glycyrrhizic acid. In the present study, we cloned the cDNA coding 3-hydroxy-3-methylglutary CoA reductase (HMGR) involved in glycyrrhizic acid biosynthesis in Glycyrrhiza uralensis. The corresponding cDNA was expressed in Escherichia coli as fusion proteins. Recombinant HMGR exhibited catalysis activity in reduction of HMG-CoA to mevalonic acid (MVA) just as HMGR isolated from other species. Because HMGR gene is very important in the biosynthesis of glycyrrhizic acid in Glycyrrhiza uralensis, this work is significant for further studies concerned with strengthening the efficacy of Glycyrrhiza uralensis by means of increasing glycyrrhizic acid content and exploring the biosynthesis of glycyrrhizic acid in vitro.

Glycyrrhiza uralensis transcriptome landscape and study of phytochemicals.

Medicinal and industrial properties of phytochemicals (e.g. glycyrrhizin) from the root of Glycyrrhiza uralensis (licorice plant) made it an attractive, multimillion-dollar trade item. Bioengineering is one of the solutions to overcome such high market demand and to protect plants from extinction. Unfortunately, limited genomic information on medicinal plants restricts their research and thus biosynthetic mechanisms of many important phytochemicals are still poorly understood. In this work we utilized the de novo (no reference genome sequence available) assembly of Illumina RNA-Seq data to study the transcriptome of the licorice plant. Our analysis is based on sequencing results of libraries constructed from samples belonging to different tissues (root and leaf) and collected in different seasons and from two distinct strains (low and high glycyrrhizin producers). We provide functional annotations and the expression profile of 43,882 assembled unigenes, which are suitable for various further studies. Here, we searched for G. uralensis-specific enzymes involved in isoflavonoid biosynthesis as well as elucidated putative cytochrome P450 enzymes and putative vacuolar saponin transporters involved in glycyrrhizin production in the licorice root. To disseminate the data and the analysis results, we constructed a publicly available G. uralensis database. This work will contribute to a better understanding of the biosynthetic pathways of secondary metabolites in licorice plants, and possibly in other medicinal plants, and will provide an important resource to further advance transcriptomic studies in legumes.

[Study on the spatial and temporal expression of beta-AS gene of Glycyrriza uralensis].

OBJECTIVE: To reveal the temporal and spatial specificity of the expression of beta-AS gene of Glycyrriza uralensis. METHODS: Used PCR to obtain the cDNA of beta-AS gene of Glycyrriza uralensis at different time and from different part and Gel-Pro to carry out the densitometric analysis of the electrophoretic band, then calculate the relative expression. RESULTS: The spatial specificity experiment showed that beta-AS gene didn't express in the overground part of Glycyrriza uralensis,while in the underground part,the expression of beta-AS in root tip was higher than that of rootstock. And the temporal specificity experiment showed that the expression of beta-AS gene of Glycyrriza uralensis could be divided into 4 stages. From December to February, the expression of beta-AS gene was under the detection limit. From March to May, beta-AS gene began to express. From May to September,the expression of beta-AS gene kept at a high level. And in October and November the expression of beta-AS gene began to decrease. CONCLUSION: When the beta-AS gene of Glycyrriza uralensis is researched, the root tip is the suitable plant material and May, June, August and September are the right acquisition time.

[Establishment of detection system of CNVs HMGR, SQS1, beta-AS synthase gene of Glycyrrhiza uralensis].

OBJECTIVE: To establish a stabilized and reliable detection system of CNVs of HMGR, SQS1, beta-AS gene of Glycyrrhiza uralensis. METHOD: Real time PCR was used to detect the CNVs of HMGR, SQS1, beta-AS gene of G. uralensis. RESULT: In the quantitative detection experiments of HMGR, SQS1, beta-AS gene of G. uralensis, the change of value of C(t) was 25.82-25.88, 29.01-29. 08, 15.52-15.56, 19.06-19.08 respectively, the alue of SD was 0.033, 0.032, 0.024, 0.011 respectively, and the value of CV was 0.12%, 0.22%, 0.16%, 0.06% respectively. CONCLUSION: The repeatability of detection system of Real time PCR was stabilized and reliable, and the method could be used to detect the CNVs of HMGR, SQS1, beta-AS gene of G. uralensis.

[Mechanism of genuineness of liquorice Glycyrrhiza uralensis based on CNVs of HMGR, SQS1 and beta-AS gene].

This study is to reveal the correlation between CNVs of HMGR, SQS1, beta-AS gene and genuineness of liquorice. Real-time PCR was used to detect the copy number of HMGR, SQS1, beta-AS gene of liquorice. According to the results, the range of the copy number variation of HMGR gene was between 1 and 3, the copy number of SQS1 gene was 1 or 2, and the copy number of beta-AS gene was only 1. On the basis of the copy number of HMGR, SQS1 and beta-AS gene, there were five groups, type A (2 + 1 + 1), type B (1 + 1 + 1), type C (3 + 2 + 1), type D (2 + 2 + 1) and type E (3 + 1 + 1). There were two types, type A and type B, in Hangjinqi of Inner Mongolia, and the ratio of A to B was 1:1.3. There were also two types, type A and type B, in Chifeng of Inner Mongolia, and the ratio of A to B was 3:1. There were four types, type A, type B, type C and type D, in Yanchi of Ningxia province, and the ratio of A to B was 1:5.1. There were three types, type A, type B and type E, in Minqin of Gansu province, and the ratio of A to B was 2:1. So CNVs mainly existed in the liquorice from Ningxia and Gansu provinces. While the genetic background of liquorice from Hangjinqi of Inner Mongolia was stabilized. The results of the experiment proved that the correlation between CNVs and origins was one of the reasons of genuineness of liquorice.

[Researches on influence of squalene synthase gene polymorphism on catalytic efficiency of its encode enzyme in Glycyrrhiza uralensis].

OBJECTIVE: To analyse the polymorphism of squalene synthase gene and reveal the influence of squalene synthase (SQS) gene polymorphism on the catalytic efficiency of its encode enzyme in Glycyrrhiza uralensi. METHOD: The total RNA was extracted. PCR was used to amplify the coding sequences of squalene synthase gene, which were sequenced and analysed. The expression vectors containing different SQS gene sequences, including SQS1C, SQS1F, SQS2A, SQS2B, were constructed and transformed into Escherichia coli BL21. The fusion protein was induced to express by IPTG, then was isolated, purified and used to carry out the enzymatic reaction in vitro. GC-MS was used to analyse the production. RESULT: There were three kinds of gene polymorphism existing in SQS1 gene of G. uralensis, including single nucleotide polymorphism (SNPs), insertion/deletion length polymorphism (InDels) and level of amino acid, the proportion of conservative replace of SQS1 was 53.94%, and there were 2 mutational sites in structural domains. The proportion of conservative replace of SQS2 was 60%, and there was 1 mutational site in structural domains. The production squalene could be detected by GC-MS in all the 4 kinds of enzymatic reactions. The capacity of accumulating squalene of SQS1F was higher than other SQS genes. CONCLUSION: The polymorphism of SQS gene was quite abundant in G. uralensis, which maybe the molecular foundation of the formation of high-quality liquorice.

[Researches on the influence of 3-hydroxy-3-methylglutary-coenzyme A reductase gene polymorphism on catalytic efficiency of its encode enzyme in Glycyrrhiza uralensis].

OBJECTIVE: To analyse the effect of expression proteins containing different escherichia coli of 3-hydroxy-3-methylglutary-coenzyme A reductase(HMGR) genic mutation on the conversion efficiency of MVA with GC-MS method, in order to lay a foundation for revealing the function of HMGR gene polymorphism of Glycyrrhiza uralensis in the production of high-quality G. uralensis medicines. METHOD: The expression carrier was established from four HMGR genic mutation types cloned from G. uralensis and transformed into Escherichia coli BL21. The protein was induced to express, detected and purified. The purified protein was adopted for in vitro enzymatic reaction. TLC and GC-MS were used for qualitative and quantitative analysis on reaction products. RESULT: The catalytic activity of L/V genotype(-HSL and -HSV) was similar, and so was the catalytic activity of the genotype with GA insertion (GALLV and GALSV), but the catalytic activity of the latter was around 2 times higher than that of the former. CONCLUSION: The functional gene polymorphism of G. uralensis may be the molecular foundation for the production of high-quality G. uralensi medicines.

[Analysis on correlation between 3-hydroxy-3-methylglutary-coenzyme A reductase gene polymorphism of Glycyrrhiza uralensis and content of glycyrrhizic acid].

OBJECTIVE: To reveal the 3-hydroxy-3-methylglutary-coenzyme A reductase (HMGR) gene polymorphism of Glycyrrhiza uralensis, and the correlation between HMGR gene polymorphism and the content of glycyrrhizic acid. METHOD: Liquorice plants containing different content of glycyrrhizic acid were used as materials. RT-PCR was used to amplify their HMGR gene sequences, which were connected with vector pMD19-T for clone sequencing. Multiple alignments were performed to analyse HMGR gene polymorphism of G. uralensis. Then the correlation between HMGR gene polymorphism and the content of glycyrrhizic acid was revealed. RESULT: HMGR gene sequences polymorphism included codon mutation, base substitution mutation, copy number polymorphism and allele heterozygosity. There were 4 types of mutations in HMGR gene coding amino acid sequences, namely -HSL, -HSV, GALLV, GALSV. Among them, -HSV type was common in liquorice plants, -HSL type only existed in liquorice plants with low content of glycyrrhizic acid, and GALSV type only existed in liquorice plants with high content of glycyrrhizic acid. CONCLUSION: HMGR gene sequences of G. uralensis are highly polymorphic and related to the content of glycyrrhizic acid.

[Cloning and characterization of 3-hydroxy-3-methylglutary CoA reductase cDNA of Glycyrrhiza uralensis].

OBJECTIVE: To clone and analysis the sequence of 3-hydroxy-3-methylglutary CoA reductase (HMGR) cDNA from Glycyrrhiza uralensis. METHOD: The primers were designed based on the conservative region of HMGR nucleic acids sequence from public database. The target gene was obtained from root of G. uralensis by use of homologous cDNA amplificati on and RACE technologies. The sequence alignment was performed using BLAST. The open reading frame was identified by use of the ORF Finder. The protein domains were defined by use of Prosite software. Clustal was used to conduct multiple amino acid sequence alignment and MEGA 5.0 was used to conduct the phylogenetic tree. RESULT: The GuHMGR cDNA sequence was obtained contains 1 842 bp contains a 1 722 bp ORF, encoding 573 amino acids with 3-hydroxy-3-methylglutary CoA reductases family profile. Deduced amino acid sequence had 84% and 76% homology to the amino acid sequence of Pisum sativum, Medicago truncatula. CONCLUSION: The cloning of 3-hydroxy-3-methylglutary CoA reductase (HMGR) cDNA will provide a foundation for exploring the function of HMGR in glycyrrhizin biosynthesis.

[Cloning and sequence analysis of squalene synthase gene and cDNA in Glycyrrhiza uralensis].

OBJECTIVE: To clone and sequence the open reading frame and genomic sequence of squalene synthase (SQS) from Glycyrrhiza uralensis. METHOD: The primers were designed according to cDNA sequence of SQS from G. glabra reported by Hiroaki HAYASHI, SQS cDNA was cloned with total RNA extracted from roots of G. uralensis. Specific fragments were amplified by RT-PCR and then were cloned and sequenced. SQS DNA was cloned with total DNA extracted from roots of G. uralensis. Specific fragments were amplified by PCR and then were cloned and sequenced. RESULT: GuSQS1 (GenBank accession number: GQ266154) was 1 242 bp in length encoding proteins with 412 amino acid. NCBI Blast x search results showed GuSQS1 had the highest amino acid similarity to the corresponding proteins from G. uralensis. The identities of GuSQS1 with the two proteins were 98. 55% and 88. 62%. SQS (GenBank accession number: GQ180932) gene with 4 484 bp containing 13 exons and 12 introns was then amplified by PCR with genomic DNA extracted from roots of G. uralensis. CONCLUSION: These findings of cloning and sequencing the open reading frame and genomic sequence of squalene synthase (SQS) from G. uralensis brought some new clues for the further exploration of SmSQS function in sterol and terpenes biosynthesis.