AaABCG40 Enhances Artemisinin Content and Modulates Drought Tolerance in Artemisia annua .

The phytohormone Abscisic acid (ABA) regulates plant growth, development, and responses to abiotic stresses, including senescence, seed germination, cold stress and drought. Several kinds of researches indicate that exogenous ABA can enhance artemisinin content inA. annua. Some transcription factors related to ABA signaling are identified to increase artemisinin accumulation through activating the artemisinin synthase genes. However, no prior study on ABA transporter has been performed inA. annua. Here, we identified a pleiotropic drug resistance (PDR) transporter geneAaPDR4/AaABCG40fromA. annua.AaABCG40was expressed mainly in roots, leaves, buds, and trichomes. GUS activity is primarily observed in roots and the vascular tissues of young leaves inproAaABCG40:GUStransgenicA. annuaplants. WhenAaABCG40was transferred into yeast AD12345678, yeasts expressingAaABCG40accumulated more ABA than the control. TheAaABCG40overexpressing plants showed higher artemisinin content and stronger drought tolerance. Besides, the expression ofCYP71AV1in OE-AaABCG40plants showed more sensitivity to exogenous ABA than that in both wild-type and iAaABCG40plants. According to these results, they strongly suggest that AaABCG40 is involved in ABA transport inA. annua.