Aging affects artemisinin synthesis in Artemisia annua

Artemisinin (ART) is the most effective component in malaria treatment, however, the extremely low content restricts its clinical application. Therefore, it is urgent to increase the yield of ART. ART gradually accumulates with aging, small RNA (sRNA) and transcriptome analysis were applied on the leaves of 2-week-old (2 w) and 3-month-old (3 m) A. annua respectively. Among all the annotated sRNAs, 125 were upregulated and 128 downregulated in the 3 m sample compared to the 2 w one. Whereas 2183 genes were upregulated and 2156 downregulated. Notably, the level of miR156 and several annotated miRNAs gradually decreased while SPLs increased. In addition, the genes on ART biosynthesis pathway were significantly upregulated including ADS, CYP71AV1, ADH1, DBR2 and ALDH1, and so were the positive transcription factors like AaERF1, AaORA and AaWRKY1 indicating that age influences the ART biosynthesis by activating the expression of the synthesizing genes as well as positive transcription factors. This study contributes to reveal the regulatory effects of age on ART biosynthesis both in sRNA and transcription levels.