title: Herbivore induction of jasmonic acid and chemical defences reduce photosynthesis in Nicotiana attenuata.
abstract: Herbivory initiates a shift in plant metabolism from growth to defence that may reduce fitness in the absence of further herbivory. However, the defence-induced changes in carbon assimilation that precede this reallocation in resources remain largely undetermined. This study characterized the response of photosynthesis to herbivore induction of jasmonic acid (JA)-related defences in Nicotiana attenuata to increase understanding of these mechanisms. It was hypothesized that JA-induced defences would immediately reduce the component processes of photosynthesis upon attack and was predicted that wild-type plants would suffer greater reductions in photosynthesis than plants lacking JA-induced defences. Gas exchange, chlorophyll fluorescence, and thermal spatial patterns were measured together with the production of defence-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 defence metabolites in wild-type plants, whereas plants lacking JA-induced defences suffered minimal suppression in photosynthesis and no increase in defence metabolite production. This suppression in photosynthesis occurred only after sustained defence signalling and defence chemical mobilization, whereas a short bout of feeding damage only transiently altered components of photosynthesis. It was identified that lipoxygenase signalling interacted with photosynthetic electron transport and that the resulting JA-related metabolites reduced photosynthesis. These data represent a metabolic cost to mounting a chemical defence against herbivory and link defence-signalling networks to the differential effects of herbivory on photosynthesis in remaining leaf tissues in a time-dependent manner.
authors.affiliation: Department of Plant Biology and Institute of Genomic Biology,  University of Illinois, Urbana, IL,  USA.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Nabity
authors.forename: Jorge A
authors.initials: JA
authors.lastname: Zavala
authors.forename: Evan H
authors.initials: EH
authors.lastname: DeLucia
mesh_terms: D000818:Animals; D002734:Chlorophyll / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism*; D015536:Down-Regulation; D060434:Herbivory / Q000502:physiology*; D006790:Host-Parasite Interactions; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism; D018402:Manduca / Q000502:physiology*; D054883:Oxylipins / Q000378:metabolism*; D010788:Photosynthesis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000378:metabolism* / Q000469:parasitology*
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; D010940:Plant Proteins; D002734:Chlorophyll; C011006:jasmonic acid; D008084:Lipoxygenase