Enhancement of Sesquiterpenoid Production by Methyl Jasmonate in <i>Atractylodes chinensis</i> Adventitious Root Culture and its Transcriptional Regulation

Adventitious root (AR) culture of Atractylodes chinensis is an efficient platform for sustainable production of its sesquiterpenoid compounds (atractylon and β-eudesmol). However, their limited accumulation levels need an effective elicitation approach, and the present study solved this problem using methyl jasmonate (MeJA) as an elicitor. The effects of its treatment concentration and duration on metabolite production were investigated. The ARs treated with 100 µM MeJA for 7 d increased atractylon and β-eudesmol by 3.64- and 1.90-fold, respectively, compared with the control. We further performed transcriptome analysis to explore the transcriptional regulation mechanism of the MeJA elicitation. A total of 124,464 unigenes were identified in A. chinensis ARs, of which 3,568 genes were upregulated and 3,864 genes were downregulated with the MeJA treatment. The MeJA treatment activated the endogenous jasmonic acid biosynthesis and signaling pathways and sesquiterpenoid biosynthesis. In addition, MeJA treatment more significantly activated genes of the methylerythritol phosphate pathway than of the mevalonate pathway. In addition, 14 genes encoding terpene synthase were identified to be significantly upregulated. A total of 2,700 transcription factors (TFs) were identified in A. chinensis ARs, of which Tify, MYB and MADS were significantly enriched under the MeJA treatment. We predicted a new antagonistic interaction between MYC2 and CPP TFs, which was significantly regulated by the MeJA treatment. The results of real-time quantitative PCR and enzyme activity assays proved the reliability of the transcriptome data. This study will help improve the in vitro production system of A. chinensis sesquiterpenoids and understand the transcriptional regulation mechanism of MeJA elicitation.