The ecological interaction between plants and herbivores has promoted the evolution of defense and offense characteristics of both parties. Specialized metabolites, including volatile organic compounds (VOCs), constitute a key defensive mechanism of plants, helping to reduce/prevent damage by herbivores and indirectly attracting their natural enemies. However, in the absence of herbivores, as occurs in invaded ranges, natural selection may favor the reduction in costly chemical defenses. Here, we assessed the production of VOCs in both damaged and undamaged leaves of plants of Datura stramonium from Mexico (native) and Spain (non-native). The emissions of VOCs were detected and compared, along with the induction extended to neighboring undamaged leaves. A total of 45 VOCs were detected and differences in chemical diversity and concentration between plants of different origin and between damaged and undamaged leaves. Notably, native populations exhibited greater VOCs diversity and higher emission levels than non-native populations, highlighting population-specific differences in both constitutive and induced chemical defenses. Expression analysis of the gene implicated in terpenoid biosynthesis (DsTPS10) demonstrated damage-induced upregulation. Gene expression patterns coupled with metabolic profiles suggest a potential defense capability of native populations as compared with non-native populations of recent evolution in the absence of the D. stramonium’s coevolved herbivores.
Velez-Haro et al. (Thu,) studied this question.