A Basic Leucine Zipper Transcription Factor, AabZIP1, Connects Abscisic Acid Signaling with Artemisinin Biosynthesis in Artemisia annua

Abstract

Artemisinin is a sesquiterpenoid especially synthesized in the Chinese herbal plant, Artemisia annua, which is widely used in the treatment of malaria. Artemisinin accumulation can be enhanced by exogenous abscisic acid (ABA) treatment. However, it is not known how ABA signaling regulates artemisinin biosynthesis. A global expression profile and phylogenetic analysis as well as the dual-LUC screening revealed that a basic leucine zipper family transcription factor from A. annua (namely AabZIP1) was involved in ABA signaling to regulate artemisinin biosynthesis. AabZIP1 had a higher expression level in the inflorescences than in other tissues; ABA treatment, drought, and salt stress strongly induced the expression of AabZIP1. Yeast one-hybrid assay and electrophoretic mobility shift assay (EMSA) showed that AabZIP1 bound to the ABA-responsive elements (ABRE) in the promoter regions of the amorpha-4,11-diene synthase (ADS) gene and CYP71AV1, which are two key structural genes of the artemisinin biosynthetic pathway. A mutagenesis assay showed that the C1 domain in the N-terminus of AabZIP1 was important for its transactivation activity. Furthermore, the activation of ADS and CYP71AV1 promoters by AabZIP1 was enhanced by ABA treatment in transient dual-LUC analysis. The AabZIP1 variant with C1 domain deletion lost the ability to activate ADS and CYP71AV1 promoters regardless of ABA treatment. Notably, overexpression of AabZIP1 in A. annua resulted in significantly increased accumulation of artemisinin. Our results indicate that ABA promotes artemisinin biosynthesis, likely through 1 activation of ADS and CYP71AV1 expression by AabZIP in A. annua. Meanwhile, our findings reveal the potential value of AabZIP1 in genetic engineering of artemisinin production.

Transcriptome Analysis of JA Signal Transduction, Transcription Factors, and Monoterpene Biosynthesis Pathway in Response to Methyl Jasmonate Elicitation in Mentha canadensis L.

“…Compared with well-studied metabolic pathways such as flavonoids, the transcriptional regulation of terpene metabolism has been validated in a few studies. Several TFs have been identified from plants including A. annua (AaWRKY1, AaERF1, AaERF2, AabZIP1, and AaMYC2), Gossypium arboretum (GaWRKY1), Taxus chinensis (TaWRKY1), Hevea brasiliensis (EREBP1 and HbWRKY1), and O. sativa (OsTGAP1) that regulate terpene biosynthesis [21,22,23,42,43,44,45,46,47,48]. In Mentha species M. spicata , two TFs MsYABBY5 and MsMYB ( M. spicata MYB DNA-binding protein) have been reported that negatively regulate monoterpene production [49,50].…”

Transcriptome Analysis of Genes Associated with the Artemisinin Biosynthesis by Jasmonic Acid Treatment under the Light in Artemisia annua

“…The AaHD1 played an important role in promoting the JA-mediated glandular trichome initiation and thus improved the artemisinin content in A. annua (Yan et al, 2016). For the ABA signaling to artemisinin accumulation in A. annua , the AabZIP1, a basic leucine zipper TF, was identified to activate the expression of AaADS and AaCYP71AV1 and promote artemisinin biosynthesis (Zhang et al, 2015). Besides, the AabHLH1 was strongly induced by ABA and could bind to the promoters of the AaADS and AaCYP71AV1 which positively regulated the biosynthesis of artemisinin (Ji et al, 2014).…”

“…A. annua seeds were sown in pots filled with compost and placed in a growth chamber under the growth condition described previously (Zhang et al, 2015). Nicotiana benthamiana used for Dual-Luciferase (Dual-LUC) assay was also grown in pots under the same growth conditions as for A. annua .…”

Identification of Putative Genes Involved in Limonoids Biosynthesis in Citrus by Comparative Transcriptomic Analysis

“…Previous research reported that TFs could regulate multiple genes in the biosynthesis of indole alkaloids (Van Moerkercke et al, 2015), artemisinins (Yu et al, 2012; Zhang et al, 2015), anthocyanins (Butelli et al, 2012; Rinaldo et al, 2015) and flavonols (Misra et al, 2010; Stracke et al, 2010). This study concludes twenty-six TFs including AP2, WRKY, bHLH , and MYBs demonstrated certain relationships with the biosynthesis of limonoids.…”