AabZIP1 confers drought tolerance and promotes artemisinin biosynthesis in Artemisia annua

Water deficiency is one of the most major factors that limit plant growth and agricultural productivity. Previous studies showed the biomass and artemisinin content reduced significantly in A. annua plant under water scarcity. However, the molecular mechanism by which A. annua responds to drought stress is not well understood. In this study, AabZIP1 was identified to be involved in the responsive process to drought stress in A. annua. AabZIP1 could activate the expression of two wax biosynthesis genes, AaCER1 and AaCYP86A1, by directly binding to their promoters. Overexpression of AabZIP1 significantly promoted the expression of AaCER1 and AaCYP86A1 and led to enhanced cuticular waxes biosynthesis, thus significantly elevating the tolerance to water deficiency in A annua. Additionally, AabZIP1 positively regulates the expression of AaMYC2 by binding to its promoter, a MYC family transcription factor which positively regulates the expression of artemisinin biosynthesis genes, like ALDH1, DBR2 and CYP71AV1. Overexpression of AabZIP1 caused the upregulation of the expression of AaMYC2 and artemisinin biosynthesis genes, leading to an increase of artemisinin content. Taken together, our results indicate that AabZIP1 plays a positive role in the regulation of drought tolerance and artemisinin biosynthesis in A annua.