Interplay between AaMYC2-LIKE and AaMYC2 leads to positive regulation of Artemisinin Biosynthetic Pathway in Artemisia annua

Abstract

Abstract Background Artemisinin-based combination therapies recommended by WHO marks Artemisia annua as the only natural source of artemisinin fighting deadly disease, Malaria. Current research focuses on regulatory mechanism of biosynthetic pathways where transcription factors (TFs) are main elements. TFs enhance the effectiveness of target genes via binding to cis-elements and playing regulatory hub of main pathways in plants. Results In this study, we isolated the AaMYC2 and AaMYC2-LIKE from Artemisia annua and performed combinatory experiments with respect to the regulation of the Artemisinin biosynthetic pathway. Our results depict that AaMYC2 and AaMYC2-LIKE TFs are transcriptionally active, and in co-transformation are responsible for increased units of β-galactosidase in transactivation and β-galactosidase assay as compared to individual transformation in yeast cells. AaMYC2 physically interacts with AaMYC2-LIKE in yeast cells and in the nucleus of onion epidermal cells as shown by Yeast Two-Hybrid and the Bimolecular Fluorescence Complementation (BiFC) assays. The expression of artemisinin biosynthetic genes and trichome development genes were elevated more in co-transformed transgenic lines of AaMYC2 and AaMYC2-LIKE as compared to individual AaMYC2 and AaMYC2-LIKE transgenic lines and wildtype. Also an increase in artemisinin content was depicted in co-transformed transgenic lines than individual transgenic lines of AaMYC2 and AaMYC2-LIKE while artemisinin content was significantly reduced in AaMYC2-RNAi/AaMYC2-LIKE lines, revealing importance of functional AaMYC2 in the synergistic regulatory role along with AaMYC2-LIKE in the regulation of the artemisinin biosynthetic pathway. Conclusion Our study confirms that AaMYC2 and AaMYC2-LIKE physically interact and act synergistically with respect to elevation of Artemisinin content by regulating key biosynthetic and trichome development genes in Artemisia annua.