Combined Transcriptomic and Metabolomic Analysis Reveals an Ethylene-Activated Regulatory Model on Monoterpenoid Indole Alkaloid Biosynthesis in Catharanthus roseus.

Catharanthus roseus contains nearly 200 bioactive monoterpenoid indole alkaloids (MIAs) that are effective in treating cancer and other diseases. Ethylene plays a significant role in enhancing MIA biosynthesis, and we have found that it greatly induces the accumulation of anhydrovinblastine. However, the regulatory mechanisms underlying this process are not yet fully understood. In this study, a comprehensive analysis of the metabolome and transcriptome of C. roseus was conducted to identify two EIN3/EIL transcription factors, CrEIN3 and CrEIL1, which act as key components mediating the ethylene signal to upregulate MIA biosynthesis. Both CrEIN3 and CrEIL1 were found to upregulate the expression of MIA biosynthetic genes and the activator gene ORCA3, while repressing the expression of repressor genes GBF1 and ZCT1, resulting in increased vinblastine production in C. roseus. CrEIN3 directly binds to the SGD promoter, while CrEIL1 interacts with JA-induced BIS2 to enhance upregulation of the iridoid pathway, thereby further promoting downstream MIA biosynthesis and strengthening the accumulation of bisindole MIAs. Our findings reveal an ethylene-activated regulatory model consisting of CrEIN3 and CrEIL1 that integrates JA-induced BIS2 to cooperatively regulate MIA production in C. roseus, shedding light on the mechanism of ethylene signal regulating MIA biosynthesis. This research provides a foundation for understanding plant hormone regulation of alkaloid metabolism, which will contribute to future efforts in developing high-yielding MIAs in plant or yeast-based platforms.