Investigating the Underlying Molecular Regulation Behind Methyl Jasmonate’s Role in the Terpenoid Production of the Saga Plant (Abrus precatorius): MYC2 Transcription Factors and Cis-Acting Regulatory Elements Region of Genes Involved in Triterpenoid Biosynthesis

Abstract

Abrus precatorius, colloquially known as the Saga plant, produces various secondary metabolites with valuable pharmaceutical properties such as glycyrrhizin and abrusoside. Methyl jasmonate (MeJA) is a phytohormone known to regulate the expression of the MYC2 transcription factor, which in turn promotes the biosynthesis of secondary metabolites in plants. Understanding the resolution to enhance the production of triterpenoid saponins like glycyrrhizin and abrusoside in Abrus precatorius would be beneficial. However, knowledge about the regulatory mechanisms underlying the biosynthesis of these compounds in this plant is still limited. This study aimed to conduct an in silico investigation of the role of Abrus precatorius MYC2 (ApMYC2) in increasing the expression of the enzymes that synthesize β-amyrin (a glycyrrhizin precursor) and cycloartenol (an abrusoside precursor) when induced by MeJA treatment. The 3D protein structures of ApMYC2 were predicted, and the promoter regions of β-amyrin synthase (ApβaS) and cycloartenol synthase (ApCaS) genes were screened for MeJA-responsive cis-acting regulatory elements. Additionally, a DNA-protein docking simulation was also performed to assess the interaction between the ApMYC2 transcription factor and the MeJA-responsive element located in the ApβaS and ApCaS promoter region. The analysis suggests that four out of five ApMYC2 predicted 3D protein structures may be fully functional by the presence of a complete set of domains. Furthermore, three MeJA-responsive elements (i.e. Myc motif, E-box, and G-box) were identified upstream of the ApβaS and ApCaS gene sequence. The docking simulation between ApMYC2 and these cis-acting regulatory elements demonstrated good docking scores and high confidence. These findings suggest that ApMYC2 likely plays a significant role in regulating the ApβaS and ApCaS gene expression and potentially increasing the yield of glycyrrhizin and abrusoside in Abrus precatorius.