title: Potato tuber herbivory increases resistance to aboveground lepidopteran herbivores.
abstract: Plants mediate interactions between aboveground and belowground herbivores. Although effects of root herbivory on foliar herbivores have been documented in several plant species, interactions between tuber-feeding herbivores and foliar herbivores are rarely investigated. We report that localized tuber damage by Tecia solanivora (Guatemalan tuber moth) larvae reduced aboveground Spodoptera exigua (beet armyworm) and Spodoptera frugiperda (fall armyworm) performance on Solanum tuberosum (potato). Conversely, S. exigua leaf damage had no noticeable effect on belowground T. solanivora performance. Tuber infestation by T. solanivora induced systemic plant defenses and elevated resistance to aboveground herbivores. Lipoxygenase 3 (Lox3), which contributes to the synthesis of plant defense signaling molecules, had higher transcript abundance in T. solanivora-infested leaves and tubers than in equivalent control samples. Foliar expression of the hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase (HQT) and 3-hydroxy-3-methylglutaryl CoA reductase I (HMGR1) genes, which are involved in chlorogenic acid and steroidal glycoalkaloid biosynthesis, respectively, also increased in response to tuber herbivory. Leaf metabolite profiling demonstrated the accumulation of unknown metabolites as well as the known potato defense compounds chlorogenic acid, α-solanine, and α-chaconine. When added to insect diet at concentrations similar to those found in potato leaves, chlorogenic acid, α-solanine, and α-chaconine all reduced S. exigua larval growth. Thus, despite the fact that tubers are a metabolic sink tissue, T. solanivora feeding elicits a systemic signal that induces aboveground resistance against S. exigua and S. frugiperda by increasing foliar abundance of defensive metabolites.
authors.affiliation: Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853, USA.
authors.forename: Pavan
authors.initials: P
authors.lastname: Kumar
authors.affiliation: Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853, USA.
authors.forename: Erandi Vargas
authors.initials: EV
authors.lastname: Ortiz
authors.affiliation: Department of Entomology, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Etzel
authors.initials: E
authors.lastname: Garrido
authors.affiliation: Department of Entomology, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Katja
authors.initials: K
authors.lastname: Poveda
authors.affiliation: Boyce Thompson Institute for Plant Research, 533 Tower Road, Ithaca, NY, 14853, USA. gj32@cornell.edu.
authors.forename: Georg
authors.initials: G
authors.lastname: Jander
mesh_terms: D000818:Animals; D060434:Herbivory; D018515:Plant Leaves; D018517:Plant Roots; D011198:Solanum tuberosum; D018411:Spodoptera
keywords: Plant defense; Plant–insect interactions; Spodoptera exigua; Systemic signaling; Tecia solanivora