Enhancement of artemisinin content and biomass in Artemisia annua by exogenous GA3 treatment

Abstract

Artemisinin is a promising and potent antimalarial drug naturally produced by the plant Artemisia annua L. but in very low yield. Its artemisinin content is known to be greatly affected by both genotype and environmental factors. In this study, the production of artemisinin and leaf biomass in Artemisia annua L. was significantly increased by exogenous GA 3 treatment. The effect of GA 3 application on expression of proposed key enzymes involved in artemisinin yield was examined in both wild type (007) and FPS-overexpression (253-2) lines of A. annua. In the wild type (007) at 6 h post GA 3 application there was an abrupt rise in FPS, ADS and CYP71AV1 expression and at 24 h a temporary and significant peak in artemisinin (1.45-fold higher than the control). After GA 3 application in line 253-2, there was a dramatic rise in expression of FPS at 3 h, CYP71AV1 at 9 h and ADS at 72 h and accumulation of artemisinin after 7 days, which was a delay when compared with the wild type plant. Thus, increased artemisinin content from exogenous GA 3 treatment was associated with increased expression of key enzymes in the artemisinin biosynthesis pathway. Interestingly, exogenous GA 3 continuously enhanced artemisinin content from the vegetative stage to flower initiation in both plant lines and gave significantly higher leaf biomass than in control plants. Consequently, the artemisinin yield in GA 3 -treated plants was much higher than in control plants. Although the maximum artemisinin content was found at the full blooming stage [2.1% dry weight (DW) in 007 and 2.4% DW in 253-2], the highest artemisinin yield in GA 3 -treated plants was obtained during the flower initiation stage (2.4 mg/plant in 007 and 2.3 mg/plant in 235-2). This was 26.3 and 27.8% higher, respectively, than in non-treated plants 007 and 253-2. This study showed that exogenous GA 3 treatment enhanced artemisinin production in pot experiments and should be suitable for field application.

Cloning and characterization of DELLA genes in Artemisia annua

“…Exogenous GA treatment can increase artemisinin production in A. annua (Weathers et al, 2005;Zhang et al, 2005;Aftab et al, 2010;Banyai et al, 2011). However, the molecular mechanism of GA-modulated artemisinin production remains elusive.…”

Time-course analysis of the artemisinin biosynthesis, and expression of genes coding for artemisinin pathway enzymes, in response to exogenous salicylic and gibberellic acids

“…2 and 3). However, Zhang et al (2005) reported no difference in the transcription pattern of ADS gene by RNA gel blot analysis, while upregulation of FDS , ADS and CYP71AV1 in response to GA3 has been reported by Banyai et al (2010). At 72 h after treatment, all of the studied genes were down-regulated, ranging from 7.5-to 46.5-fold, which was accompanied with a consequent reduction in artemisinin to the same level as in control plants.…”

“…An application of exogenous GA3 on A. annua plants significantly increased the production of artemisinin, up-regulating three genes in its biosynthesis pathway and inducing the conversion of artemisinic acid to artemisinin (Zhang et al, 2005;Banyai et al, 2010). However, in recent research no induction of artemisinin biosynthesis by GA3 was reported (Maes et al, 2011).…”

Artemisia species in vitro cultures for production of biologically active secondary metabolites

“…The authors also suggested that there is a crosstalk between the ABA signaling pathway and the artemisinin biosynthetic pathway, and that CYP71AV1 (amorpha-4,11-diene C-12 oxidase gene), which was induced most significantly, may play a key regulatory role in the artemisinin biosynthetic pathway. Banyai et al (2011) observed enhancement of artemisinin content and leaf biomass in A. annua by exogenous GA 3 treatment. The increased artemisinin content was associated with an increased synthesis of key enzymes in the artemisinin biosynthesis pathway due to the GA 3 application.…”