Transcription factor <scp>AabHLH5</scp> participates in <scp>JA</scp> signaling and negatively regulates artemisinin biosynthesis in <i>Artemisia annua</i>

The plant hormone jasmonic acid (JA) can increase artemisinin content in Artemisia annua L., but the mechanism regulating artemisinin biosynthesis needs further study. Basic helix-loop-helix (bHLH) transcription factors play important roles in plant growth and development, defense responses, secondary metabolism, etc. However, the role of bHLH transcription factors in response to JA signaling in artemisinin biosynthesis has not been well reported. Therefore, it is of great significance to investigate whether potential bHLH transcription factors in A. annua can regulate artemisinin biosynthesis through the JA signaling pathway. In this study, transcriptome data of A. annua treated with MeJA (Methyl Jasmonate) were used to identify candidate bHLH transcription factors that respond to JA. Furthermore, AabHLH5 and two potential JASMONATE-ZIM DOMAIN (JAZ) proteins interacting with AabHLH5 were identified through plant transformation, yeast two-hybrid and bimolecular fluorescence complementarity assays. Furthermore, the molecular mechanism by which bHLH5 participates in the JA signaling pathway and negatively regulates artemisinin biosynthesis was verified.