ABSTRACT
Artemisia annua also known as Qinghao, is a kind of traditional Chinese medicine. Its active ingredient is artemisinin, a sesquiterpene lactone compound with a peroxy bridging group structure. A. annua is an effective antimalarial drug. Artemisinin, a secondary metabolite in A. annua, can be induced by many physical and chemical factors, such as salinity, moisture, light, and plant hormones. Temperature, as an important growth factor, also has a great influence on the synthesis of artemisinin. This article aims to study the effect of high temperature on inducing artemisinin biosynthesis in A. annua. The A. annua seedlings were placed at 25, 40 °C, and the samples were taken after 0, 3, 12 and 36 h. The content of artemisinin in each sample was determined by liquid chromatography-mass spectrometry. Total RNA was extracted from the samples, and then transcriptome sequencing and real-time fluorescence quantitative PCR were used to quantitatively analyze the expression of the key enzyme genes in artemisinin synthesis pathway and competition pathway. The results showed that artemisinin content was increased by 20%, 42% and 68% after 3, 12, 36 h of treatment at 40 °C. The expression levels of FDS, ALDH1, CYP71AV1 and ADS were up-regulated by 4.3, 3.3, 2.5, 1.9 times, and the expression levels of SQS and BPS were down-regulated by 37% and 90% respectively. In summary, high temperature can promote the biosynthesis of artemisinin by promoting the expression of synthetase genes in artemisinin synthesis pathway and inhibiting the expression of synthetase genes in artemisinin-competition pathway.