摘要
Plants of Artemisia annua produce artemisinin, a sesquiterpene lactone widely used in malaria treatment. Amorpha-4,11-diene synthase （ADS）, a sesquiterpene synthase, and CYP71AV1, a P450 monooxygenase, are two key enzymes of the artemisinin biosynthesis pathway. Accumulation of artemisinin can be induced by the phytohormone jasmonate （JA）. Here, we report the characterization of two JA-responsive AP2 family transcription factors-AaERF1 and AaERF2-from A. annua L. Both genes were highly expressed in inflorescences and strongly induced by JA. Yeast one- hybrid and electrophoretic mobility shift assay （EMSA） showed that they were able to bind to the CRTDREHVCBF2 （CBF2） and RAVlAAT （RAA） motifs present in both ADS and CYP71AV1 promoters. Transient expression of either AaERF1 or AaERF2 in tobacco induced the promoter activities of ADS or CYP71AV1, and the transgenic A. annua plants overexpressing either transcription factor showed elevated transcript levels of both ADS and CYP71AV1, resulting in increased accumulation of artemisinin and artemisinic acid. By contrast, the contents of these two metabolites were reduced in the RNAi transgenic lines in which expression of AaERF1 or AaERF2 was suppressed. These results demonstrate that AaERF1 and AaERF2 are two positive regulators of artemisinin biosynthesis and are of great value in genetic engineering of arte- misinin production.
Plants of Artemisia annua produce artemisinin, a sesquiterpene lactone widely used in malaria treatment. Amorpha-4,11-diene synthase （ADS）, a sesquiterpene synthase, and CYP71AV1, a P450 monooxygenase, are two key enzymes of the artemisinin biosynthesis pathway. Accumulation of artemisinin can be induced by the phytohormone jasmonate （JA）. Here, we report the characterization of two JA-responsive AP2 family transcription factors-AaERF1 and AaERF2-from A. annua L. Both genes were highly expressed in inflorescences and strongly induced by JA. Yeast one- hybrid and electrophoretic mobility shift assay （EMSA） showed that they were able to bind to the CRTDREHVCBF2 （CBF2） and RAVlAAT （RAA） motifs present in both ADS and CYP71AV1 promoters. Transient expression of either AaERF1 or AaERF2 in tobacco induced the promoter activities of ADS or CYP71AV1, and the transgenic A. annua plants overexpressing either transcription factor showed elevated transcript levels of both ADS and CYP71AV1, resulting in increased accumulation of artemisinin and artemisinic acid. By contrast, the contents of these two metabolites were reduced in the RNAi transgenic lines in which expression of AaERF1 or AaERF2 was suppressed. These results demonstrate that AaERF1 and AaERF2 are two positive regulators of artemisinin biosynthesis and are of great value in genetic engineering of arte- misinin production.
基金
This research was supported by State Key Basic Research Program of China （2007CB108800）, the National Natural Science Foundation of China （30630008）, and the National HighTech Program of China （2007AA021501 ）.ACKNO WLEDGMENTS We thank CYP71AV1. discussions Ke-Xuan Tang for supplying the promoter sequence of We thank Ji-Rong Huang and Gao-Jie Hong for he pfu No conflict of interest declared
