Comparative Transcriptome Analysis of High and Low Thujone-Producing Artemisia argyi Reveals Candidate Genes for Thujone Synthetic and Regulatory Pathway

Artemisia argyi Levl. et Van (A. argyi) is a traditional medicinal plant, which is widely used in health, food and medicine. Thujone is an important cyclic monoterpene derivative in the volatile oil of A. argyi leaves with multiple efficacy. Although the thujone synthetic pathway has been preliminarily analyzed in very few species, genes related to the thujone content in A. argyi leaves remain largely unknown. In this study, we identify candidate genes involved in the synthesis and regulation of thujone content in A. argyi leaves by the comparative transcriptome analysis of two group materials with high and low thujone content. A total of 89 candidate genes related to thujone content are identified including one gene involved in the mevalonate pathway, three genes involved in the methylerythritol phosphate pathway, 19 genes involved in the metabolic process from geranyl pyrophosphate to thujone (four b-terpene synthase, five cytochrome P450, five dehydrogenase, and five reductase-encoding genes) and 66 transcription factor-encoding genes. Taken together, our results provide valuable gene resources for further analyzing the synthetic and regulatory pathway of thujone in A. argyi.