TRICHOME AND ARTEMISININ REGULATOR 2 positively regulates trichome development and artemisinin biosynthesis in Artemisia annua

Abstract

Glandular secretory trichomes (GSTs) are regarded as biofactories for synthesizing, storing, and secreting artemisinin. It is necessary to figure out the initiation and development regulatory mechanism of GSTs to cultivate high-yielding Artemisia annua. Here, we identified an MYB transcription factor, AaTAR2, from bioinformatics analysis of the A. annua genome database and Arabidopsis trichome development-related genes. AaTAR2 is mainly expressed in young leaves and located in the nucleus. Repression and overexpression of AaTAR2 resulted in a decrease and increase, respectively, in the GSTs numbers, leaf biomass, and the artemisinin content in transgenic plants. Furthermore, the morphological characteristics changed obviously in trichomes, suggesting AaTAR2 plays a key role in trichome formation. In addition, the expression of flavonoid biosynthesis genes and total flavonoid content increased dramatically in AaTAR2-overexpressing transgenic plants. Owing to flavonoids possibly counteracting emerging resistance to artemisinin in Plasmodium species, AaTAR2 is a potential target to improve the effect of artemisinin in clinical therapy. Taken together, AaTAR2 positively regulates trichome development and artemisinin and flavonoid biosynthesis. A better understanding of this 'multiple functions' transcription factor may enable enhanced artemisinin and flavonoids yield. AaTAR2 is a potential breeding target for cultivating high-quality A. annua.

Enhancing artemisinin content in and delivery from Artemisia annua: a review of alternative, classical, and transgenic approaches

“…AaORA down-regulation by hairpin-mediated RNAi decreased dihydroartemisinic acid as well as artemisinin. Zhou et al (2020) identified an MYB transcription factor, AaTAR2 which acts as a positive regulator of glandular trichome initiation and development, and its over-expression resulted in increased artemisinin content. Recently, Qin et al (2021) isolated and characterized another glandular trichome specific transcription factor AaMYB17 in A. annua.…”

Discovery and modulation of diterpenoid metabolism improves glandular trichome formation, artemisinin production and stress resilience in Artemisia annua

“…S12). Through a gene regulatory network, 21 GA‐responsive TFs were selected (correlation threshold > 300) for future study and considered potential regulators in trichome development and artemisinin biosynthesis (Dataset S3) (Zhou et al ., 2020).…”

“…The Artemisia annua cultivar used in this study was ‘Huhao 1’ (Zhou et al ., 2020). Young leaves of Artemisia annua were collected for phytohormone quantification and transcriptome analysis.…”

“…The mobile phase was methanol/0.1% formic acid/water/0.1% formic acid solution (Table S2). The amount of artemisinin in wild‐type (WT) and transgenic plants was determined by HPLC‐tandem mass spectrometry (MS/MS) as previously described (Zhou et al ., 2020).…”

Transcriptional regulation of flavonoid biosynthesis in Artemisia annua by AaYABBY5

“…Most of the R2R3-MYB genes have been shown to play regulatory roles in flavonoid biosynthesis in A. annua . Recently, the MYB family transcription factor AaTAR2 from A. annua was reported to synergistically regulate both artemisinin and flavonoids 29 ; however, the mechanism of the regulation of flavonoid biosynthesis was not found. In plants, flavonoid biosynthesis is tightly regulated by MBW complexes that interact with late biosynthetic genes.…”