Effect of external stress on density and size of glandular trichomes in full-grown Artemisia annua, the source of anti-malarial artemisinin

Kjær, Anders; Grevsen, Kai; Jensen, Martin

doi:10.1093/aobpla/pls018

Cited by 30 publications

(27 citation statements)

References 38 publications

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“…() support the hypothesis that artemisinin and some of its structural analogues present in the leaves A. annua L. are localized entirely within the subcuticular space of glands on the leaf surface. The number of GT on leaves is directly proportional to artemisinin accumulation (Arsenault et al ., ; Graham et al ., ; Kjær et al ., ). In our study, artemisinin content was higher in the subcuticular space of GTs of Bgl1‐transformed plants than untransformed control plants.…”

Section: Discussionmentioning

confidence: 97%

“…The presence of glandular trichomes (GT) on the epidermis of the A. annua leaf is related to biosynthesis of several secondary metabolites and impacts accumulation of artemisinin (Kjær et al ., ). However, molecular mechanism of artemisinin biosynthesis and the development of trichomes in A. annua remain poorly understood (Tan et al ., ).…”

Section: Introductionmentioning

confidence: 97%

“…In the past, attempts have been made to enhance GT to increase accumulation of artemisinin triggered by chemical or physical stress. However, such strategies have not been successful in A. annua (Kjær et al ., ). The presence of low density of GT in A. annua is responsible for the low accumulation of artemisinin (Kjær et al ., ).…”

Section: Introductionmentioning

confidence: 97%

“…However, such strategies have not been successful in A. annua (Kjær et al ., ). The presence of low density of GT in A. annua is responsible for the low accumulation of artemisinin (Kjær et al ., ). Therefore, there is a strong positive relationship between artemisinin content and GT densities.…”

Section: Introductionmentioning

confidence: 97%

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Expression of β‐glucosidase increases trichome density and artemisinin content in transgenic Artemisia annua plants

Singh

Kumar

Daniell

2015

Plant Biotechnology Journal

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Artemisinin is highly effective against multidrug-resistant strains of Plasmodium falciparum, the etiological agent of the most severe form of malaria. However, a low level of accumulation of artemisinin in Artemisia annua is a major limitation for its production and delivery to malaria endemic areas of the world. While several strategies to enhance artemisinin have been extensively explored, enhancing storage capacity in trichome has not yet been considered. Therefore, trichome density was increased with the expression of β glucosidase (bgl1) gene in A. annua through Agrobacterium-mediated transformation. Transgene (bgl1) integration and transcript was confirmed by molecular analysis. Trichome density increased up to 20% in leaves and 66% in flowers of BGL1 transgenic plants than Artemisia control plants. High-performance liquid chromatography (HPLC, MS-TOF) data showed that artemisinin content increased up to 1.4% in leaf and 2.56% in flowers (g-1DW), similar to the highest yields achieved so far through metabolic engineering. Artemisinin was enhanced up to 5-fold in BGL1 transgenic flowers. The present study opens the possibility of increasing artemisinin content by manipulating trichomes density, which is a major reservoir of artemisinin. Combining biosynthetic pathway engineering with enhancing trichome density may further increase artemisinin yield in A. annua. Because oral feeding of Artemisia plant cells reduced parasitemia more efficiently than the purified drug, reduced drug resistance and cost of prohibitively expensive purification process, enhanced expression should play a key role in making this valuable drug affordable to treat malaria in a large global population that disproportionally impacts low-socioeconomic areas and underprivileged children.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 97%

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Expression of β‐glucosidase increases trichome density and artemisinin content in transgenic Artemisia annua plants

Singh

Kumar

Daniell

2015

Plant Biotechnology Journal

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“…the structure, ultrastructure, size, density, his-Volume 8 | Number 1 | January | 2018 tochemistry, and chemical points of view of such structures, have been carried out plenty, particularly on that of Lamiaceae and Asteraceae [8,9]. Kjaer et al (2012) [10] studied the size and density of secretory structure (glandular trichomes) in Artemisia annua. Using histochemical assay, the secretory structure of Salvia officinalis is known containing terpenoids, alkaloids, tannin, flavonoids, and essential oils that are the characteristics of Salvia as aromatic plant [11].…”

Section: Introductionmentioning

confidence: 99%

Tetracera scandens as a Medicinal Plant: Secretory Structures, Histochemistry, and Antibacterial Activity

Muliyah

Sulistijorini

Sulistyaningsih

et al. 2018

J.Trop.Life.Science

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Tetrascera scandens, a member of Dilleniaceae, is used for traditional medicine; the stem is utilized by the Anak Dalam tribe of Jambi Province, Sumatera island, Indonesia, to treat diarrhea symptoms. The aims of this study were to identify the secretory structures, histochemical aspects, and the antibacterial potency of T. scandens stem. Histological study of the secretory structures of T. scandens stem was carried out. The species has idioblast cells and trichomes as its secretory structures. Histochemical analysis indicated the substance secreted by T. scandens idioblast cells mainly contains alkaloids, terpenoids, and phenols. Trichomes of T. scandens only contain flavonoids. The antibacterial activity of methanol extracts was tested against Staphyllococcus aureus and Escherichia coli. Different concentration of extracts was tested using the well diffusion method. According to the results, 100 mg/mL T. scandens extract showed the best inhibitory activity with a maximum inhibition zone of 17.7 mm against S. aureus and of 12.5 mm against E. coli. This study provides scientific evidence that the stem of T. scandens has antibacterial activity and justifies its use by the local community.

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Optimisation of artemisinin and scopoletin extraction from Artemisia annua with a new modern pressurised cyclic solid–liquid (PCSL) extraction technique

Zarrelli

Pollio

Aceto

et al. 2019

Phytochemical Analysis

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Introduction Artemisia annua is a small herbaceous plant belonging to the Asteraceae family declared therapeutic by the World Health Organisation, in particular for its artemisinin content, an active ingredient at the base of most antimalarial treatments, used every year by over 300 million people. In the last years, owing to low artemisinin content, research of new ways to increase the yield of the plant matrix has led to the use of the total extract taking advantage from the synergic and stabilising effects of the other components. Objective In this work we evaluated and compared the content of artemisinin and scopoletin in extracts of A. annua collected in the Campania Region (southern Italy), by two different extraction processes. Methodology Artemisia annua plants were extracted by traditional maceration (TM) in hydroalcoholic solution as a mother tincture prepared according to the European Pharmacopeia and by pressurised cyclic solid–liquid (PCSL) extraction, a new generation method using the Naviglio extractor. Results The results showed that the PCSL extraction technique is more effective than traditional methods in extracting both phytochemicals, up to 15 times more, reducing the extraction times, without using solvents or having risks for the operators, the environment and the users of the extracts. Conclusion The Naviglio extractor provides extracts with an artemisinin and scopoletin content eight times higher than the daily therapeutic dose, which should be evaluated for its stability over time and biological properties for possible direct use for therapeutic purposes.

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Effect of external stress on density and size of glandular trichomes in full-grown Artemisia annua, the source of anti-malarial artemisinin

Abstract: The experiments demonstrate that stress treatments to large Artemisia annua plants have a minor promoting effect on the initiation of glandular trichomes in developing leaves, and a maturing effect on glandular trichomes later in the life time of the individual trichome.

Cited by 30 publications

References 38 publications

Expression of β‐glucosidase increases trichome density and artemisinin content in transgenic Artemisia annua plants

Expression of β‐glucosidase increases trichome density and artemisinin content in transgenic Artemisia annua plants

Tetracera scandens as a Medicinal Plant: Secretory Structures, Histochemistry, and Antibacterial Activity

Optimisation of artemisinin and scopoletin extraction from Artemisia annua with a new modern pressurised cyclic solid–liquid (PCSL) extraction technique

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