Inducible defenses, which provide enhanced resistance after initial attack, are nearly universal in plants. This defense signaling
cascade is mediated by the synthesis, movement, and perception of jasmonic acid and related plant metabolites. To characterize
the long-term persistence of plant immunity, we challenged Arabidopsis (Arabidopsis thaliana) and tomato (Solanum
lycopersicum) with caterpillar herbivory, application of methyl jasmonate, or mechanical damage during vegetative growth and
assessed plant resistance in subsequent generations. Here, we show that induced resistance was associated with transgenerational
priming of jasmonic acid-dependent defense responses in both species, caused caterpillars to grow up to 50% smaller
than on control plants, and persisted for two generations in Arabidopsis. Arabidopsis mutants that are deficient in jasmonate
perception (coronatine insensitive1) or in the biogenesis of small interfering RNA (dicer-like2 dicer-like3 dicer-like4 and nuclear
RNA polymerase d2a nuclear RNA polymerase d2b) do not exhibit inherited resistance. The observation of inherited resistance in
both the Brassicaceae and Solanaceae suggests that this trait may be more widely distributed in plants. Epigenetic resistance to
herbivory thus represents a phenotypically plastic mechanism for enhanced defense across generations.