Spatial profiling of maytansine during the germination process of Maytenus senegalensis seeds

The ecological role of maytansine, an important antineoplastic and antimicrobial compound with high cytotoxicity, particularly as a chemical defense compound has remained elusive since its discovery in the 1970s in Maytenus and Putterlickia plants. In the present study, we have used MALDI-imaging-HRMS to visualize the occurrence as well as spatial and temporal distribution of maytansine in a Maytenus senegalensis plant, seeds obtained from the mother plant during seeding stage, through the germination of the seeds, and finally up to the establishment of seedlings (or daughter plants). Although the mother plant was devoid of maytansine, the bioactive compound was found to be distributed in the cotyledons and the endosperm of the seeds with an augmented accretion towards the seed coat. Furthermore, maytansine was always detected in the emerging seedlings, particularly the cortex encompassing the radicle, hypocotyl, and epicotyl. The typical pattern of accumulation of maytansine not only in the seeds but also during germination provides a proof-of-concept that M. senegalensis is ecologically primed to trigger the production of maytansine in vulnerable tissues such as seeds during plant reproduction. By utilizing maytansine as chemical defense compound against predators and/or pathogens, the plant can ensure viability of the seeds and successful germination, thus leading to the next generation of daughter plants.