CrGRF1/4 Mediating Light Signal to Regulate Monoterpenoid Indole Alkaloid Biosynthesis In Catharanthus roseus.

Light plays a pivotal role as an environmental factor throughout the entire life cycle of plants, influencing plant growth, development, stress responses, and specialised metabolism. In this study, we identified six growth regulating factors (GRFs) in Catharanthus roseus through genome sequence analysis, and notably, two GRFs, CrGRF1 and CrGRF4, exhibited responsiveness to light signals. By manipulating the expression of CrGRF1 and CrGRF4 in C. roseus leaves, both through overexpression and silencing, we observed their capacity to enhance the accumulation of monoterpenoid indole alkaloids (MIAs) by upregulating the expression of 10-hydroxygeraniol oxidoreductatse (Cr10HGO) and 7-deoxyloganetic acid synthase (Cr7DLS). Furthermore, yeast one-hybrid and dual-luciferase reporter assays confirmed that CrGRF1 and CrGRF4 directly activate Cr10HGO expression by binding to the TFmatrixID_0441 cis-elements (ctTTCAGa) within its promoter region. This study sheds new light on the crucial role played by the growth regulating factor (GRF) gene family in regulating specialised metabolic pathways in plants. Elucidating the roles of CrGRF1 and CrGRF4 lays an essential foundation for future research to decipher the molecular mechanisms governing light-controlled MIA production in C. roseus.