Complete Chloroplast Genome Sequence of Erigeron breviscapus and Characterization of Chloroplast Regulatory Elements

Erigeron breviscapus is a famous medicinal plant. However, the limited chloroplast genome information of E. breviscapus, especially for the chloroplast DNA sequence resources, has hindered the study of E. breviscapus chloroplast genome transformation. Here, the complete chloroplast (cp) genome of E. breviscapus was reported. This genome was 152,164bp in length, included 37.2% GC content and was structurally arranged into two 24,699bp inverted repeats (IRs) and two single-copy areas. The sizes of the large single-copy region and the small single-copy region were 84,657 and 18,109bp, respectively. The E. breviscapus cp genome consisted of 127 coding genes, including 83 protein coding genes, 36 transfer RNA (tRNA) genes, and eight ribosomal RNA (rRNA) genes. For those genes, 95 genes were single copy genes and 16 genes were duplicated in two inverted regions with seven tRNAs, four rRNAs, and five protein coding genes. Then, genomic DNA of E. breviscapus was used as a template, and the endogenous 5' and 3' flanking sequences of the trnI gene and trnA gene were selected as homologous recombinant fragments in vector construction and cloned through PCR. The endogenous 5' flanking sequences of the psbA gene and rrn16S gene, the endogenous 3' flanking sequences of the psbA gene, rbcL gene, and rps16 gene and one sequence element from the psbN-psbH chloroplast operon were cloned, and certain chloroplast regulatory elements were identified. Two homologous recombination fragments and all of these elements were constructed into the cloning vector pBluescript SK (+) to yield a series of chloroplast expression vectors, which harbored the reporter gene EGFP and the selectable marker aadA gene. After identification, the chloroplast expression vectors were transformed into Escherichia coli and the function of predicted regulatory elements was confirmed by a spectinomycin resistance test and fluorescence intensity measurement. The results indicated that aadA gene and EGFP gene were efficiently expressed under the regulation of predicted regulatory elements and the chloroplast expression vector had been successfully constructed, thereby providing a solid foundation for establishing subsequent E. breviscapus chloroplast transformation system and genetic improvement of E. breviscapus.

Advances in Chemical Constituents, Clinical Applications, Pharmacology, Pharmacokinetics and Toxicology of Erigeron breviscapus

Dengzhanxixin (DZXX), the dried whole plant of Erigeron breviscapus (Vaniot) Hand.-Mazz., belonging to Compositae and first published in Materia Medica of South Yunnan by Lan Mao in the Ming Dynasty (1368 AD–1644 AD), is included in Medicinal Materials and Decoction Pieces of the 2020 edition of the Pharmacopeia of the People’s Republic of China. Its main chemical components are flavonoids that mainly include flavonoid, flavonols, dihydroflavones, flavonol glycosides, flavonoid glycosides, coffee acyl compounds, and other substances, such as volatile oil compounds, coumarins, aromatic acids, pentacyclic terpenoids, phytosterols, and xanthones. Among them, scutellarin and 1,5-dicoffeoylquininic acid are the main active components of DZXX. DZXX has pharmacological effects, such as improving cerebral and cerebrovascular ischemia, increasing blood flow, inhibiting platelet aggregation, promoting antithrombotic formation, improving microcirculation, reducing blood viscosity, protecting optic nerves, exhibiting anti-inflammatory properties, scavenging free radicals, and eliciting antioxidant activities. It is widely used in the treatment of cardiovascular and cerebrovascular ischemic diseases, kidney diseases, liver diseases, diabetic complications, and glaucoma. Pharmacokinetic studies have shown that the active components of DZXX have a low bioavailability and a high elimination rate in vivo. Nevertheless, its utilization can be improved through liposome preparation and combination with other drugs. Acute and subacute toxicity studies have shown that DZXX is a safe medicinal material widely used in clinical settings. However, its target and drug action mechanism are unclear because of the complexity of its composition. In this paper, the clinical application and pharmacological toxicology of DZXX are reviewed to provide a reference for further studying its active components and action mechanism.

Metabolism and Pharmacological Mechanisms of Active Ingredients in Erigeron breviscapus

Background: Erigeron breviscapus (Vant.) Hand-Mazz. is a plant species in the Compositae family. More than 10 types of compounds—such as flavonoids, caffeinate esters, and volatile oils—have been identified in Erigeron breviscapus; however, it remains unknown as to which compounds are associated with its clinical efficacy. In recent years, flavonoids and phenolic acids have been considered as the main effective components of Erigeron breviscapus. The metabolism and mechanisms of these compounds in vivo have been extensively studied to improve our understanding of the drug. Method: In the present review, we summarize the relationships among these compounds, their metabolites, and their pharmacodynamics. Many methods have been implemented to improve the separation and bioavailability of these compounds from Erigeron breviscapus. Results: In China, Erigeron breviscapus has been used for many years. In recent years, through the study of its metabolism and the mechanisms of its effective components, the effects of Erigeron breviscapus in the treatment of various diseases have been extensively studied. Findings have indicated that Erigeron breviscapus improves cardiovascular and cerebrovascular function, and that one of its ingredients, scutellarin, has potential value in the treatment of Alzheimer's disease, cancer, diabetic vascular complications, and other conditions. In addition, phenolic acid compounds and their metabolites also play an important role in anti-oxidation, anti-inflammation, and improving blood lipids. Conclusion: Erigeron breviscapus plays an important role in the prevention and treatment of cardiovascular/cerebrovascular diseases, neuroprotection, and cancer through many different mechanisms of action. Further investigation of its efficacious components and metabolites may provide more possibilities for the clinical application of traditional Chinese medicine and the development of novel drugs.

EbARC1, an E3 Ubiquitin Ligase Gene in Erigeron breviscapus, Confers Self-Incompatibility in Transgenic Arabidopsis thaliana

Erigeron breviscapus (Vant.) Hand.-Mazz. is a famous traditional Chinese medicine that has positive effects on the treatment of cardiovascular and cerebrovascular diseases. With the increase of market demand (RMB 500 million per year) and the sharp decrease of wild resources, it is an urgent task to cultivate high-quality and high-yield varieties of E. breviscapus. However, it is difficult to obtain homozygous lines in breeding due to the self-incompatibility (SI) of E. breviscapus. Here, we first proved that E. breviscapus has sporophyte SI (SSI) characteristics. Characterization of the ARC1 gene in E. breviscapus showed that EbARC1 is a constitutive expression gene located in the nucleus. Overexpression of EbARC1 in Arabidopsis thaliana L. (Col-0) could cause transformation of transgenic lines from self-compatibility (SC) into SI. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays indicated that EbARC1 and EbExo70A1 interact with each other in the nucleus, and the EbARC1-ubox domain and EbExo70A1-N are the key interaction regions, suggesting that EbARC1 may ubiquitinate EbExo70A to regulate SI response. This study of the SSI mechanism in E. breviscapus has laid the foundation for further understanding SSI in Asteraceae and breeding E. breviscapus varieties.