Molecular cloning and structural analysis of key enzymes in Tetrastigma hemsleyanum for resveratrol biosynthesis.

Resveratrol (RES), a plant antitoxin, has antioxidant, anti-inflammatory, anti-cancer and cardiovascular protection effects. It has been reported that RES can be stably detected in a Chinese herbal medicinal plant Tetrastigma hemsleyanum. At present, the research of T. hemsleyanum mainly focused on the discovery of new compounds and pharmacology. However, there were few studies on the molecular mechanism of the synthesis of secondary metabolites in T. hemsleyanum. In this experiment, four key enzymes (ThPAL/ThC4H/Th4CL/ThRS) involved in the RES biosynthesis pathway were cloned and obtained. They contained an open reading frame (ORF) of 2139 bp, 1518 bp, 1716 bp and 1035 bp, encoding 712, 505, 571 and 344 amino acids, separately. Various bioinformatics tools were used to analyze these deduced protein domains, secondary structures, three-dimensional (3D) structures and phylogenetic trees. Subsequently, quantitative primers were designed to conduct the tissue-specific expression. Quantitative results displayed that the four genes were expressed in all tested tissues, and their expression in root tubers was more stable. Moreover, the subcellular localization of the four genes was studied by constructed recombinant green fluorescent expression vectors. Herein, by digging out the key enzyme genes in the biosynthesis of RES in T. hemsleyanum, this experiment tried to reveal the expression patterns of these key enzyme genes. It also provided the basis for the research on the molecular level, which will help people further illuminate and clarify the biosynthesis and regulation mechanism of secondary metabolites in T. hemsleyanum.

The research progresses and future prospects of Tetrastigma hemsleyanum Diels et Gilg: A valuable Chinese herbal medicine.

ETHNOPHARMACOLOGICAL RELEVANCE: Tetrastigma hemsleyanum Diels et Gilg, known as Sanyeqing in China, was an extensively used folk Chinese herbal medicine. This plant had been validated to be highly effective for treating high fever, pneumonia, hepatitis, gastritis, cervicitis, lymphatic tuberculosis, septicemia, and viral meningitis. AIM OF THE REVIEW: As a review in T. hemsleyanum, this article aims to provide a critical and comprehensive evaluation for future research as well as the development of new drugs. The possible uses and future research directions of this plant were also discussed. MATERIALS AND METHODS: A literature search was conducted on different scientific search engines, including Google Scholar, Science Direct, PubMed, Web of Science, and CNKI. Additional information was obtained from classic books about Chinese herbal medicine and scientific databases. RESULTS: T. hemsleyanum was a perennial herb climbing vine, which was mainly based on field cultivation. About 150 chemical compounds have been isolated from T. hemsleyanum, including flavonoids, phenolic acids, polysaccharides, triterpenoids, steroids, and organic acids. Studies on the physiological aspects of T. hemsleyanum have been focused on the effects of light and fertilizer on their growth, and few other studies have been conducted. The plant had widespread pharmacological effects on the immune system, as well as anti-tumor, anti-inflammatory, analgesic, and antipyretic. CONCLUSIONS: T. hemsleyanum was a valuable traditional Chinese medical herb with pharmacological activities that mainly affected the immune system. This review summarized its botanical description, cultivation techniques, physiology, ethnopharmacology, chemical components, and pharmacological functions. This information suggested that we should focus on the development of new drugs related to T. hemsleyanum. Meanwhile, it was important to emphasize the traditional use of T. hemsleyanum, avoiding over-harvesting that exerted a great impact on resource scarcity. And developing its new clinical usage and comprehensive utilize would augment the therapeutic potentials of T. hemsleyanum.

Transcriptome profiling reveals candidate flavonol-related genes of Tetrastigma hemsleyanum under cold stress.

BACKGROUND: Tetrastigma hemsleyanum Diels et Gilg is a valuable medicinal herb, whose main bioactive constituents are flavonoids. Chilling sensitivity is the dominant environmental factor limiting growth and development of the plants. But the mechanisms of cold sensitivity in this plant are still unclear. Also, not enough information on genes involved in flavonoid biosynthesis in T. hemsleyanum is available to understand the mechanisms of its physiological and pharmaceutical effects. RESULTS: The electrolyte leakage, POD activity, soluble protein, and MDA content showed a linear sustained increase under cold stress. The critical period of cold damage in T. hemsleyanum was from 12 h to 48 h. Expression profiles revealed 18,104 differentially expressed genes (DEGs) among these critical time points. Most of the cold regulated DEGs were early-response genes. A total of 114 unigenes were assigned to the flavonoid biosynthetic pathway. Fourteen genes most likely to encode flavonoid biosynthetic enzymes were identified. Flavonols of T. hemsleyanum might play a crucial role in combating cold stress. Genes encoding PAL, 4CL, CHS, ANR, FLS, and LAR were significantly up-regulated by cold stress, which could result in a significant increase in crucial flavonols (catechin, epicatechin, rutin, and quercetin) in T. hemsleyanum. CONCLUSIONS: Overall, our results show that the expression of genes related to flavonol biosynthesis as well as flavonol content increased in T. hemsleyanum under cold stress. These findings provide valuable information regarding the transcriptome changes in response to cold stress and give a clue for identifying candidate genes as promising targets that could be used for improving cold tolerance via molecular breeding. The study also provides candidate genes involved in flavonoid biosynthesis and may be useful for clarifying the biosynthetic pathway of flavonoids in T. hemsleyanum.

Left-right leaf asymmetry in decussate and distichous phyllotactic systems.

Leaves in plants with spiral phyllotaxy exhibit directional asymmetries, such that all the leaves originating from a meristem of a particular chirality are similarly asymmetric relative to each other. Models of auxin flux capable of recapitulating spiral phyllotaxis predict handed auxin asymmetries in initiating leaf primordia with empirically verifiable effects on superficially bilaterally symmetric leaves. Here, we extend a similar analysis of leaf asymmetry to decussate and distichous phyllotaxy. We found that our simulation models of these two patterns predicted mirrored asymmetries in auxin distribution in leaf primordia pairs. To empirically verify the morphological consequences of asymmetric auxin distribution, we analysed the morphology of a tomato sister-of-pin-formed1a (sopin1a) mutant, entire-2, in which spiral phyllotaxy consistently transitions to a decussate state. Shifts in the displacement of leaflets on the left and right sides of entire-2 leaf pairs mirror each other, corroborating predicted model results. We then analyse the shape of more than 800 common ivy (Hedera helix) and more than 3000 grapevine (Vitis and Ampelopsis spp.) leaf pairs and find statistical enrichment of predicted mirrored asymmetries. Our results demonstrate that left-right auxin asymmetries in models of decussate and distichous phyllotaxy successfully predict mirrored asymmetric leaf morphologies in superficially symmetric leaves.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

Molecular authentication of Tetrastigma hemsleyanum from its adulterant species using ISSR, CAPS, and ITS2 barcode.

Tetrastigma hemsleyanum is a rare and endangered herb, which is commercialized as the resource of anti-cancer drugs. Wild T. hemsleyanum plants are on the verge of extinction recently, there are increasing numbers of counterfeits on the market. In the present study, inter-simple sequence repeat (ISSR), Cleaved amplified polymorphic sequence (CAPS), and the internal transcribed spacer region II (ITS2) barcode were used for the first time for the authentication of T. hemsleyanum from its commonly counterfeits. ISSR analysis suggested that it was a useful method for distinguishing T. hemsleyanum from its adulterants of different genus. However, it was insufficient to distinguish T. hemsleyanum from those adulterants of the same genus. ITS2 of T. hemsleyanum and the commonly counterfeits were amplified and sequenced. The Neighbor-Joining tree constructed from the ITS2 sequences showed that T. hemsleyanum was clearly differentiated from all counterfeits samples. A mutation site in the ITS2 region of T. hemsleyanum had been found which could be recognized by the restriction endonuclease NcoI. T. hemsleyanum could be readily distinguished from counterfeits as the PCR products from T. hemsleyanum could be digested sufficiently by NcoI, while the PCR products from counterfeits could not be digested. The results indicated that CAPS and ITS2 barcode methods provided effective and accurate identification of T. hemsleyanum from all its adulterants, while ISSR could only distinguish T. hemsleyanum from its adulterants of different genus. The CAPS method developed in the present study will serve as a reliable tool for safe and effective use of T. hemsleyanum in the clinic application. It will also play an important role for the identification, management and conservation of this endangered species.

Development and characterization of microsatellite markers for the Chinese endangered medicinal plant Tetrastigma hemsleyanum.

Tetrastigma hemsleyanum (Vitaceae) is an endangered medicinal plant endemic to China. Because of its widely known efficacy for treating many health problems, wild resources of this species are currently undergoing a rapid decline. Few studies have been conducted examining the population genetics or development of microsatellite loci for this plant. In this study, 14 microsatellite loci were isolated and characterized for T. hemsleyanum using a double-suppression PCR method. Polymorphisms were tested with a total of 50 individuals from 2 natural populations. The number of alleles per locus ranged from 3-9, with an average of 7 alleles per locus. The observed and expected heterozygosity per locus ranged from 0-1 and from 0.068-0.803, respectively. The polymorphism information content value varied from 0.215-0.760. These loci may facilitate further genetic studies of populations of T. hemsleyanum and provide guidance for their conservation.

A hypothesis on the origin of genetic heterozygosity in diploids and triploids in Japanese Cayratia japonica species complex (Vitaceae).

We previously reported the occurrence of triploid strains in Japanese populations of Cayratia japonica (Thunb.) Gagnep. Interestingly, the triploid and most diploid strains had variably reduced pollen fertility. Two questions emerged from this earlier work: (1) How do triploids arise, and are they allotriploids or autotriploids? and (2) Why is there low pollen fertility in some diploid plants? We used a molecular genetic approach to determine the phylogenetic origins of triploids in C. japonica and the closely related species Cayratia tenuifolia (Wight & Arn.) Gagnep. In our analysis, we compared the sequences of the nuclear single-copy genes LEAFY and ASYMMETRIC LEAVES1. As a result, most triploids and diploids were heterozygous for the loci examined; the triploid genome shared an allele with the diploid genome, but other alleles differed between the ploidies. Therefore, Japanese populations of C. japonica and C. tenuifolia almost certainly arose from repeated hybridization events among genetically differentiated strains. Using our sequence data, we discuss possible scenarios accounting for the occurrence of triploids in the two species of Cayratia.

[Fingerprints identification of Gynostemma pentaphyllum by RAPD and cloning and analysis of its specific DNA fragment].

OBJECTIVE: To identify the resources of Gynostemma pentaphyllum and its spurious breed plant Cayratia japonica at level of DNA. METHODS: Two random primers ( WGS001, WGS004) screened were applied to do random amplification with genomic DNA extracted from Gynostemma pentaphyllum and Cayratia japonica which were collected from different habitats. After amplificated with WGS004, one characteristic fragment about 500 bp which was common to all Gynostemma pentaphyllum samples studied but not to Cayratia japonica was cloned and sequenced. Then these sequences obtained were analyzed for identity and compared by Blastn program in GenBank. RESULTS: There were obvious different bands amplified by above two primers in their fingerprints of genomic DNA. On the basis of these different bands of DNA fingerprints, they could distinguish Gynostemma pentaphyllum and Cayratia japonica obviously. Sequence alignment of seven cloned bands showed that their identities ranged from 45.7% - 94.5%. There was no similar genome sequences searched in GenBank. This indicated that these seven DNA fragments had not been reported before and they should be new sequences. CONCLUSION: RAPD technique can be used for the accurate identification of Gynostemma pentaphyllum and its counterfeit goods Cayratia japonica. Besides, these specific DNA sequences for Gynostemmna pentaphyllum in this study are useful for the further research on identification of species and assisted selection breeding in Gynostemma pentaphyllum.

[Identification of Gynostemma from their adulterant Cayratia japonica by PCR-RFLP].

OBJECTIVE: To establish a convenient and effective method for the identification of Gynostemma and Cayratia japonica. METHOD: Eight species, including Gynostemm pentaphyllum, G. pentagynum, G. cardiospermum, G. longipe, G. yixingense, G. laxiflorum, G. guangxiense and C. japonica were investigated through PCR - RFLP of six chloroplast DNA fragments. The six gene fragments were digested by six restriction endonuclease respectively, including Taq I, Hpa II, EcoR I, Rsa I, Hha I, Hind III. RESULT: Seven species of Gynostemma and their adulterant could be identified by trnK1f-trnK2r and Rsa. CONCLUSION: PCR - RFLP provides a quick, reliable molecular marker technique for identification of Cynostemma and their adulterant Cayratia japonica.

Phytoalexins from the Vitaceae: biosynthesis, phytoalexin gene expression in transgenic plants, antifungal activity, and metabolism.

Resistance of plants to infection by phytopathogenic microorganisms is the result of multiple defense reactions comprising both constitutive and inducible barriers. In grapevine, the most frequently observed and best characterized defense mechanisms are the accumulation of phytoalexins and the synthesis of PR-proteins. Particular attention has been given here to stilbene phytoalexins produced by Vitaceae, specifically, their pathway of biosynthesis (including stilbene phytoalexin gene transfer experiments to other plants) and their biological activity together with fungal metabolism.