GLANDULAR TRICHOME‐SPECIFIC WRKY 1 promotes artemisinin biosynthesis in Artemisia annua

Summary Artemisinin is a type of sesquiterpene lactone well known as an antimalarial drug, and is specifically produced in glandular trichomes of Artemisia annua . However, the regulatory network for the artemisinin biosynthetic pathway remains poorly understood. Exploration of trichome‐specific transcription factors would facilitate the elucidation of regulatory mechanism of artemisinin biosynthesis. The WRKY transcription factor GLANDULAR TRICHOME ‐ SPECIFIC WRKY 1 ( Aa GSW 1 ) was cloned and analysed in A. annua . Aa GSW 1 exhibited similar expression patterns to the trichome‐specific genes of the artemisinin biosynthetic pathway and AP 2/ ERF transcription factor Aa ORA . A β‐glucuronidase (GUS) staining assay further demonstrated that Aa GSW 1 is a glandular trichome‐specific transcription factor. Aa GSW 1 positively regulates CYP 71 AV 1 and Aa ORA expression by directly binding to the W‐box motifs in their promoters. Overexpression of Aa GSW 1 in A. annua significantly improves artemisinin and dihydroartemisinic acid contents; moreover, Aa GSW 1 can be directly regulated by Aa MYC 2 and Aab ZIP 1, which are positive regulators of jasmonate ( JA )‐ and abscisic acid ( ABA )‐mediated artemisinin biosynthetic pathways, respectively. These results demonstrate that Aa GSW 1 is a glandular trichome‐specific WRKY transcription factor and a positive regulator in the artemisinin biosynthetic pathway. Moreover, we propose that two trifurcate feed‐forward pathways involving Aa GSW 1 , CYP 71 AV 1 and Aa MYC 2 / Aab ZIP 1 function in the JA / ABA response in A. annua .