CrMYC1 transcription factor overexpression promotes the production of low abundance terpenoid indole alkaloids in Catharanthus roseus

Abstract

Catharanthus roseus is known as the only source for the low-abundance anticancer agents namely vinblastine and vincristine. Fine tuning of accumulation of such secondary metabolites is highly governed by the regulatory genes. Among these genes, Catharanthus roseus MYC1 (CrMYC1) is known as one of the key transcription factors regulating the biosynthesis of terpenoid indole alkaloid metabolites in C. roseus. In this study, CrMYC1 coding sequence (AF283506) was isolated and cloned in PBI121 plant binary vector. Then, CrMYC1 was transiently overexpressed in C. roseus leaves using agroinfiltration method. In addition to molecular analysis for confirming CrMYC1 overexpression, the profile of some chief terpenoid indole alkaloids in control and transgenic plants was evaluated by HPLC to elucidate the role of CrMYC1 in an increased in the anticancer components. The results indicated that overexpression of CrMYC1 transcription factor can increase most important terpenoid indole alkaloids including vinblastine, vincristine, and catharanthine in C. roseus. HPLC analysis of catharanthine and vinblastine contents showed about 3 and 2.5 fold increases, respectively, while the increase in vinecristine was not significant compared to that of the control. Therefore, CrMYC1 is introduced as an efficient candidate for manipulating TIA pathway in C. roseus and increasing at least the most valuable terpenoid indole alkaloids in this plant.

Application of metabolic engineering to enhance the content of alkaloids in medicinal plants

“…Transient expression was used to overexpress the CrMYC1 gene in C. roseus leaves and it was reported a 3 fold increase in catharanthine and vinblastine content, 2 days after agroinfiltration. Although CrMYC1 gene needs to be further characterized, it was concluded that it was a suitable candidate for alkaloid enrichment in C. roseus via metabolic engineering ( Sazegari et al, 2018 ). It is advisable to check the levels of transcripts and metabolites at different time points to find an optimal time, as well as replicate experiments on a large number of plants with different growth stages, since transient expression could be affected by the developmental and physiological state of the plants ( Sazegari et al, 2018 ).…”

Transgenesis as a Tool for the Efficient Production of Selected Secondary Metabolites from Plant in Vitro Cultures

“…Similar to other valuable plant metabolites, vinblastine is also of interest to modern plant biotechnology and many studies have attempted to increase its production in plant tissues. One study examined the effect of overexpression of the MYC1 transcription factor (CrMYC1) in C. roseus [90]. CrMYC1 has been characterized as one of the main components regulating the biosynthesis of terpenoid indole alkaloid metabolites in this plant.…”

Repression of ZCT1, ZCT2 and ZCT3 affects expression of terpenoid indole alkaloid biosynthetic and regulatory genes

“…The BIS1 transcriptional activator turns on expression of all genes analyzed that encode proteins in the metabolic pathway between geranyl diphosphate and loganic acid (Van Moerkercke et al, 2015;Van Moerkercke et al, 2016;Schweizer et al, 2018). The CrMYC1 transcriptional activator was identified based on its ability to bind the STR promoter (Chatel et al, 2003) and overexpression of CrMYC1 increases vinblastine, vincristine and catharanthine levels (Sazegari et al, 2018). However, Full-size  DOI: 10.7717/peerj.11624/fig- 1 information regarding which TIA and TIA-related genes may be regulated by CrMYC1 is currently lacking.…”