CONICET | Buscador de Institutos y Recursos Humanos

Herbivory initiates a shift in plant metabolism from growth to defense that may reduce fitness in the absence of further herbivory. However, the defense-induced changes in carbon assimilation that precede this reallocation in resources remain largely undetermined. We characterized the response of photosynthesis to herbivore induction of jasmonic acid (JA)-related defenses in Nicotiana attenuata to increase understanding of these mechanisms. We hypothesized that JA-induced defenses would immediately reduce the component processes of photosynthesis upon attack and predicted that wild-type plants would suffer greater reductions in photosynthesis than plants lacking JA-induced defenses. We measured gas exchange, chlorophyll fluorescence and thermal spatial patterns, and the production of defense-related metabolites after attack and through recovery. Herbivore damage immediately reduced electron transport and gas exchange in wild-type plants, and gas exchange remained suppressed for several days after attack. The sustained reductions in gas exchange occurred concurrently with increased defense metabolites in wild-type plants whereas plants lacking JA-induced defenses suffered minimal suppression in photosynthesis and no increase in defense metabolite production. This suppression in photosynthesis occurred only after sustained defense signaling and defense chemical mobilization whereas a short bout of feeding damage only transiently altered components of photosynthesis. Here we identified that lipoxygenase signaling interacts with photosynthetic electron transport and the resulting JA-related metabolites reduced photosynthesis. These data represent a metabolic cost to mounting chemical defense against herbivory and data link defense-signaling networks to the differential effects of herbivory on photosynthesis in remaining leaf tissues in a time-dependent manner.

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