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

Abstract

Summary Plants synthesize diverse diterpenoids with numerous functions in organ development and stress resistance. However, the role of diterpenoids in glandular trichome (GT) development and GT‐localized biosynthesis in plants remains unknown. Here, the identification of 10 diterpene synthases (diTPSs) revealed the diversity of diterpenoid biosynthesis in Artemisia annua. Protein–protein interactions (PPIs) between AaKSL1 and AaCPS2 in the plastids highlighted their potential functions in modulating metabolic flux to gibberellins (GAs) or ent‐isopimara‐7,15‐diene‐derived metabolites (IDMs) through metabolic engineering. A phenotypic analysis of transgenic plants suggested a complex repertoire of diterpenoids in Artemisia annua with important roles in GT formation, artemisinin accumulation and stress resilience. Metabolic engineering of diterpenoids simultaneously increased the artemisinin yield and stress resistance. Transcriptome and metabolic profiling suggested that bioactive GA4/GA1 promote GT formation. Collectively, these results expand our knowledge of diterpenoids and show the potential of diterpenoids to simultaneously improve both the GT‐localized metabolite yield and stress resistance, in planta.

Cell‐type‐specific metabolism in plants

“…For example, in trichomes that accumulate volatile compounds these may be stored in subcuticular spaces, as occurs in peppermint, or between the secretory cells as in tomato (Schuurink & Tissier, 2020). The metabolites accumulated in GTs typically have anti‐herbivory activity, making GTs an important part of plant defenses against biotic stress, but they also produce compounds with pharmaceutical applications such as the antimalarial artemisinin that accumulates in the GTs of Artemisia annua (Chen et al., 2021), meaning that their metabolism has also been studied with a view to genetic engineering (Huchelmann et al., 2017).…”

Elevation of artemisinin content by co-transformation of artemisinin biosynthetic pathway genes and trichome-specific transcription factors in Artemisia annua

“…GST structures are made up of 10 symmetric cells and are thought to be the main biofactories for artemisinin production, storage, and secretion, however, there is also a report on the production of artemisinin in the non-glandular trichomes of self-pollinated inbred A. annua ( Judd et al., 2019 ). The exclusive expression of artemisinin pathway key enzymes in GSTs, nominate them to be the true cell biofactories and the target for metabolic engineering and breeding strategies to improve their efficiency, such as by increasing their density ( Mutabingwa, 2005 ; Schilmiller et al., 2008 ; Chen et al., 2021 ). However, the lack of a model plant for GST study, as well as poor knowledge of the mechanism underlying their development, are two limiting constraints.…”

Exogenous Strigolactone (GR24) Positively Regulates Growth, Photosynthesis, and Improves Glandular Trichome Attributes for Enhanced Artemisinin Production in Artemisia annua

“…Considering the importance of this plant, substantial research has been carried out to find ways of escalating the in planta artemisinin production, as its chemical synthesis is quite complex and costly. Exogenous application of several phytohormones has been found to enhance the terpenoid biosynthesis in many aromatic plants (Shukla et al 1992 ), and numerous studies have shown the impact of exogenous application of different phytohormones like salicylic acid (Pu et al 2009 ; Aftab et al 2011a ; Kumari et al 2018 ), gibberellic acid (Aftab et al 2010 ; Banyai et al 2011 ; Chen et al 2021 ), abscisic acid (Zehra et al 2020 ), and methyl jasmonate (Aftab et al 2011b ; Zhou and Memelink 2016 ) in artemisinin enhancement. Therefore, this study was carried out to investigate the impact of exogenous GR24 treatment on growth, physiology, and artemisinin biosynthesis in A. annua .…”