Consequences of interspecific plant hybridization on metabolic diversity in naturally occurring hybrid swarms

Interspecific hybridization has influenced plant evolution and diversification. However, how hybridization may affect metabolic diversity, especially in naturally occurring hybridization zones, is unclear. In this study, we selected a Baccharis (Asteraceae) hybrid complex consisting of B. linearis, B. macraei, and B. × intermedia and characterized its metabolic profiles in multiple hybridization zones in central Chile to determine how hybridization affects plant chemistry. Untargeted liquid chromatography–time of flight mass spectrometry analysis of a total of 411 plant individuals collected in the field revealed that the hybrid B. × intermedia combines the metabolic profiles of its two parental species, B. linearis and B. macraei, independent of season, location, and environment. This combinatorial effect was observed in the specialized metabolites, while the primary metabolism did not differ between species. The metabolic diversity of the hybrid exceeded that of the parental species and was influenced by latitude, with higher metabolic diversity in the northern populations than in those in the south. In summary, our results demonstrate that natural interspecific hybridization can quickly increase the diversity of specialized metabolites. This could enhance protection against biotic or abiotic stressors, particularly in changing environmental conditions.