| 1. |
- Shen, Qian, et al.
(författare)
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The Genome of Artemisia annua Provides Insight into the Evolution of Asteraceae Family and Artemisinin Biosynthesis
- 2018
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Ingår i: Molecular Plant. - : Cell Press. - 1674-2052 .- 1752-9867. ; 11:6, s. 776-788
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Tidskriftsartikel (refereegranskat)abstract
- Artemisia annua, commonly known as sweet wormwood or Qinghao, is a shrub native to China and has long been used for medicinal purposes. A. annua is now cultivated globally as the only natural source of a potent anti-malarial compound, artemisinin. Here, we report a high-quality draft assembly of the 1.74-gigabase genome of A. annua, which is highly heterozygous, rich in repetitive sequences, and contains 63 226 protein-coding genes, one of the largest numbers among the sequenced plant species. We found that, as one of a few sequenced genomes in the Asteraceae, the A. annua genome contains a large number of genes specific to this large angiosperm clade. Notably, the expansion and functional diversification of genes encoding enzymes involved in terpene biosynthesis are consistent with the evolution of the artemisinin biosynthetic pathway. We further revealed by transcriptome profiling that A. annua has evolved the sophisticated transcriptional regulatory networks underlying artemisinin biosynthesis. Based on comprehensive genomic and transcriptomic analyses we generated transgenic A. annua lines producing high levels of artemisinin, which are now ready for large-scale production and thereby will help meet the challenge of increasing global demand of artemisinin.
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| 2. |
- Liu, Meng, et al.
(författare)
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Characterization of a trichome-specific promoter of the aldehyde dehydrogenase 1 (ALDH1) gene in Artemisia annua
- 2016
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Ingår i: Plant Cell Tissue and Organ Culture. - : Springer Science and Business Media LLC. - 0167-6857 .- 1573-5044. ; 126:3, s. 469-480
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Tidskriftsartikel (refereegranskat)abstract
- Artemisinin is a frequently used anti-malaria drug extracted from glandular trichomes (GSTs) in Artemisia annua L. In this study, we report on the characterization of the promoter of aldehyde dehydrogenase 1 (ALDH1) involved in the biosynthesis of artemisinin. A 1620-bp promoter fragment was cloned upstream of the ALDH1 start codon. Putative regulatory cis-acting elements are predicted by software, revealing that this gene is affected by complex factors. The activity of the ALDH1 promoter was analyzed using a reporter gene GUS. GUS expression showed a spatial difference in leaves at different ages. In young leaves, GUS staining was exclusively discovered in GSTs. In older leaves, both GSTs and T-shaped trichomes (TSTs) showed GUS signals. Only TSTs showed GUS staining in lower leaves. No GUS staining was detected in the bottom leaves. The result demonstrates that the ALDH1 promoter is trichome-specific. The RT-Q-PCR analysis revealed that both wild-type and recombinant promoters showed similar activity in A. annua. After application of exogenous 100 μM methyl jasmonate, 100 μM gibberellin and 100 μM salicylic acid separately, the transcript levels were increased significantly, indicating that ALDH1 may play an important role in the response to hormones in A. annua.
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| 3. |
- Matias-Hernandez, Luis, et al.
(författare)
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AaMYB1 and its orthologue AtMYB61 affect terpene metabolism and trichome development in Artemisia annua and Arabidopsis thaliana
- 2017
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Ingår i: The Plant Journal. - : Wiley-Blackwell. - 0960-7412 .- 1365-313X. ; 90:3, s. 520-534
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Tidskriftsartikel (refereegranskat)abstract
- The effective anti-malarial drug artemisinin (AN) isolated from Artemisia annua is relatively expensive due to the low AN content in the plant as AN is only synthesized within the glandular trichomes. Therefore, genetic engineering of A. annua is one of the most promising approaches for improving the yield of AN. In this work, the AaMYB1 transcription factor has been identified and characterized. When AaMYB1 is overexpressed in A. annua, either exclusively in trichomes or in the whole plant, essential AN biosynthetic genes are also overexpressed and consequently the amount of AN is significantly increased. Artemisia AaMYB1 constitutively overexpressing plants displayed a greater number of trichomes. In order to study the role of AaMYB1 on trichome development and other possibly connected biological processes, AaMYB1 was overexpressed in Arabidopsis thaliana. To support our findings in Arabidopsis thaliana, an AaMYB1 orthologue from this model plant, AtMYB61, was identified and atmyb61 mutants characterized. Both AaMYB1 and AtMYB61 affected trichome initiation, root development and stomatal aperture in A. thaliana. Molecular analyses indicated that two crucial trichome activator genes are misexpressed in atmyb61 mutant plants and in plants overexpressing AaMYB1. Furthermore, AaMYB1 and AtMYB61 are also essential for gibberellin (GA) biosynthesis and degradation in both species by positively affecting the expression of the enzymes that convert GA(9) into the bioactive GA(4) as well as the enzymes involved in the degradation of GA(4). Overall, these results identify AaMYB1/AtMYB61 as a key component of the molecular network that connects important biosynthetic processes, and reveal its potential value for AN production through genetic engineering.
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