Isolation and characterization of promoter of ADS from Artemisia annua / 中国中药杂志

<p><b>OBJECTIVE</b>To try to find the ways to enhance the expression of ADS gene encoding amorpha-4,11-diene synthase, a key enzyme in artemisinin biosynthesis pathway catalyzing the formation of amorpha-4,11-diene from farnesyl diphosphate, and accelerate the artemisinin synthesis, the promoter of ADS was isolated and characterized.</p><p><b>METHOD</b>5' untranslated regions of ADS were isolated from Artemisia annua with PCR. For functional characterization, the isolated fragment was fused with GUS reporter gene and introduced into Nicotiana tabacum by Agrobacterium-mediated transformation. The GUS expression regulated by 5' untranslated regions of ADS in transgenic N. tabacum under the normal or stressed conditions were detected by histochemical staining and quantitative spectrophotometry assay.</p><p><b>RESULT</b>The 2 448 bp DNA fragment upstream of ADS coding sequence was isolated from A. annua and introduced into N. tabacum. Histochemical staining showed that the isolated fragment conferred stable GUS expression in transgenic plants. The quantitative results showed that the GUS activity in transgenic tobacco plants treated by low-temperature (4 degrees C) and ultraviolet irradiation were 1. 6 and 2.2 folds higher than that in the controls.</p><p><b>CONCLUSION</b>It was suggested that the isolated fragment had promoter activity and maybe responsive to adverse environmental stresses.</p>

Cloning and Sequencing of Artemisia annua Squalene Synthase Gene and Its cDNA / 广州中医药大学学报

【Objective】 To clone the squalene synthase gene of Artemisia annua L. for improving the quality and production of Artemisia annua L. by genetic engineering. 【Methods】 PCR amplification, RT-PCR amplification, ligation of the target fragment with a T-vector and sequence analysis of the interested gene were performed. 【Results】 An expected 3590 bp fragment was amplified by PCR and an expected 1257 bp fragment was amplified by RT-PCR. The two cloned fragments were identified by PCR and restriction enzyme digestion respectively. The preliminary sequence data indicated that the results obtained were similar to that from GenBank, and the difference was only found in several base pairs. 【Conclusion】 The squalene synthase gene and cDNA of Artemisia annua L. were successfully cloned and sequenced.

Transcriptome Analysis of Artemisinin Biosynthetic Genes / 广州中医药大学学报

Objective To investigate the expression patterns of artemisinin biosynthetic genes in Artemisia annua L.during the development stage and in different tissues,and to explore the mechanism of spatial and temporal modulators for artmisinin production.Methods The transcriptional profiles of artemisinin biosynthetic genes in the capital and cooperative pathways were quantitatively assayed by real time fluorescence quantitative-polymerase chain reaction(RTFQ-PCR) in different tissues of roots,stems,leaves and flowers,and in leaf-flourishing,pre-floral,and post-floral periods.Results The expression levels of the tested genes were extremely low in June,raised in July,and reached their peak values in August(before flowering),but dropped gradually in September(after blooming).In August,the transcription levels of the tested genes increased by 3 to 15 times compared to the lowestlevels.In particular,ADS and CYP71AV1 mRNA levels had the great elevation,which were 12 and 15 times as much as those in June.During the flowering period,the artemisinin biosynthetic genes mRNA expression was detectable in roots,stems,leaves and flowers,and the expression levels had no obvious difference except that ADS mRNA level in leaves was 2 times higher than that in other tissues(P

Cloning of Squalene Synthase Gene from Saccharomyces cerevisiae and Construction of Yeast Expression Vector / 广州中医药大学学报

Objective To lay the foundation for studying the synthesis of artemisinin in microorganism,squalene synthase(SS) gene,a key enzyme gene from Saccharomyces cerevisiae,was cloned and a yeast expression vector was constructed.Methods After amplification of SS gene by polymerase chain reaction(PCR),ligation to T-vector and analysis of the cloned sequence,enzyme digestion and reconfirmation of the target gene,the antisense yeast expression vector was constructed by inverted insertion of the target gene into a yeast expression vector,pGAPZ?A,and digested with two restriction enzymes for vertifying the recombinant.Results The length of SS gene was 1335bp.The preliminary sequence data indicated that SS gene obtained from the experiment had a high sequence homology with that from GenBank,except for a few base pairs.The antisense yeast expression vector has been constructed and vertified by digesting with two enzymes.Conclusion SS gene from Saccharomyces cerevisiae has been successfully cloned and sequenced.An antisense yeast expression vector has been also constructed.

Transient expression of recombinant human cytokine genes in transgenic Chinese materia medica cells / 中草药

Object To explore the feasibility of breeding genetic modified (GM) medicine by expressing human cytokine in transgenic Chinese materia medica Methods Human interferon ? gene and RANTES gene available from the amplification in vitro were enzymatically excised, recoveried, and inserted into intermediate vectors The recombinants were identified by double enzyme digestion of EcoRⅠand HindⅢ The plasmids were extracted from Escherichia coli and introduced into A tumefaciens, and the transformants harboring binary vectors were screened by addition of antibiotics of kanamycin (Km) and rifampicin (Rif), and the explants of M charantia and P vulgaris were transformed by co cultivation of leaf disks with A tumefaciens strain Results RT PCR was applied to detect the transient expression of human interferon ? gene and RANTES gene in transformed medicinal herbal calli Conclusion The expression of recombinant human interferon ? gene and RANTES gene in transgenic M charantia and P vulgaris cells was firstly reported, which opens an alternative road to antivirus, especially anti AIDS virus, by using transgenic Chinese materia medica

Gene targeting of squalene synthase in Artemisia annua / 中草药

Objective To increase artemisinin yield in transgenic Artemisia annua plants by regulating metabolic affluxion through metabolic pathway engineering. Methods The gene targeting vector was constructed by squalene synthase (SS) gene of A. annua, green fluorescent protein (GFP) gene, and cytosine deaminase (CodA) gene, and the vector was introduced into Agrobacterium tumefaciens by freeze-thawing procedure. A. annua was transformed through Leaf Disk method and regenerated transgenic plants were screened by the “Step-by-Step Selection”. Results Among the transgenic A. annua plants emitting green fluorescence after expression of GFP gene, the exogenous GFP gene rather than endogenous SS gene was detected in one transgenic plant by PCR as well as hybridization of PCR products. The preliminary data showed that the wild-type SS gene was replaced by mutated SS gene in the transgenic A. annua plant. Conclusion Gene targeting of squalene synthases of A. annua is successful.

Expression of CodA gene from Escherichia coli confering a negative selection phenotype on transgenic Artemisia annua / 中草药

Objective To explore the feasibility of utilizing the cytosine deaminase A (CodA) gene as an effective negative selectable marker in Artemisia annua for gene targeting.Methods The PCR procedure was employed to amplify CodA gene from Escherichia coli.After being cloned and sequenced, the gene was inserted into a plant expression vector, pROKⅡ, and then introduced into Agrobacterium tumefaciens LBA4404 (pAL4404).The leaf disks of A.annua were transformed by the co-cultivation protocol, after which the transformed calli were selected and green shoots of A. annua were regenerated on N6 medium supplemented with 25 ?g/mL Kanamycin (Kan).Then the Kan-resistant transgenic shoots were transplanted onto the MS medium containing 500 ?g/mL 5-fluocytosine (5-FC) plus 25 ?g/mL Kan and continuously cultured for up to two weeks.Results The transgenic shoots have totally died while untransformed shoots still kept normal growth, indicating that A.annua cells introduced into the CodA gene had conferred an expected negative selection phenotype.When detected by RT-PCR, the transgenic shoots displayed a CodA-positive amplified band, but untransformed shoots gave no such CodA-specific amplified pattern.This result suggested that CodA gene had transcribed into corresponding mRNA in A.annua cells with furtherly verifying the result of phenotypic assay.Conclusion The CodA gene can be utilized as an effective negative selectable marker in A.annua for gene targeting.