Evolutionary metabolomics of specialized metabolism diversification in the genus Nicotiana highlights allopolyploidy-mediated innovations in N-acylnornicotine metabolism

Specialized metabolite (SM) diversification is a core process to plants’ adaptation to diverse ecological niches. Here we implemented a computational mass spectrometry (MS)-based metabolomics approach to explore SM diversification in tissues of 20 species covering Nicotiana phylogenetics sections. To drastically increase metabolite annotation, we created a large in silico fragmentation database, comprising more than 1 million structures, and scripts for connecting class prediction to consensus substructures. Altogether, the approach provides an unprecedented cartography of SM diversity and section-specific innovations in this genus. As a case-study, and in combination with NMR and MS imaging, we explored the distribution of N-acyl nornicotines, alkaloids predicted to be specific to Repandae allopolyploids, and revealed their prevalence in the genus, albeit at much lower magnitude, as well as a greater structural diversity than previously thought. Altogether, the novel data integration approaches provided here should act as a resource for future research in plant SM evolution.TeaserComputational metabolomics delineates main trends in the diversification of specialized metabolism in the genus Nicotiana