Retrobiosynthetic study of salicylic acid in Catharanthus roseus cell suspension cultures

Abstract

Salicylic acid (SA) is an important signal compound in systemic acquired resistance in plants. The level of this C6C1 compound in plants increases after a pathogenic attack. There are two biosynthetic pathways of SA, the phenylalanine pathway, which is thought to occur in plants, and the isochorismate pathway, which is found in microorganisms. The biosynthetic pathway of SA in plant is still a matter of debate and some studies showed that the presence of the microbial pathway in plants is also plausible. The present study deals with the production of SA in Catharanthus roseus cell suspension cultures after elicitation with a fungal elicitor (Pythium aphanidermatum extract), the development of a purification method for salicylic acid from plant extract using an ion exchange chromatography, 13C-NMR analysis of purified SA-containing extracts of Catharanthus roseus cells after a labeling experiment with [1-13C]glucose and metabolic profiling of Catharanthus roseus cells elicited with SA. Catharanthus roseus is an important medicinal plant for the production of the anti-tumor agents vincristine and vinblastine, and an excellent model for a retrobiosynthetic study as shown in some studies. We showed by chemistry that in Catharanthus roseus cell suspension cultures, SA is synthesized via the isochorismate pathway.