title: Defensive changes in maize leaves induced by feeding of Mediterranean corn borer larvae.
abstract: Plants can respond to insect attack via defense mechanisms that reduce insect performance. In this study, we examined the effects of several treatments applied to two maize genotypes (one resistant, one susceptible) on the subsequent growth and survival of Sesamia nonagrioides Lef. (Mediterranean corn borer, MCB) larvae. The treatments were infestation with MCB larvae, application of MCB regurgitant upon wounding, wounding alone, or exposure to methyl jasmonate, and they were applied at the V6-V8 stage of maize development. We also monitored changes in the concentrations of compounds known to be involved in constitutive resistance, such as cell wall-bound hydroxycinnamates and benzoxazinoids.
  
  
  
  In both maize genotypes, the leaves of plants pre-infested with MCB larvae were less suitable for larval development than those from untreated plants. Application of MCB regurgitant upon wounding, and wounding itself, resulted in leaf tissues becoming less suitable for larval growth than those of pre-infested plants, suggesting that there could be herbivore-associated effector molecules that suppress some wounding responses. A single application of MCB regurgitant did not seem to mimic feeding by MCB larvae, although the results suggested that regurgitant deposited during feeding may have enhanced ferulates and diferulates synthesis in infested vs. control plants. Jasmonic acid may play a role in mediating the maize response to MCB attack, but it did not trigger hydroxycinnamate accumulation in the leaves to a level comparable to that induced by larval leaf feeding. The EP39 maize genotype showed an increase in leaf cell wall strength by increasing hemicellulose cross-linking in response to MCB attack, while induced defenses in the EP42 plants appeared to reflect a broader array of resistance mechanisms.
  
  
  
  The results indicated that leaf feeding by MCB larvae can increase leaf antibiosis against MCB in two maize genotypes with contrasting levels of resistance against this borer. Also, the larval regurgitant played a positive role in eliciting a defense response. We determined the effects of the plant response on larval growth, and detected defense compounds related to borer resistance.
authors.affiliation: Universidad de Vigo, Agrobiología Ambiental Calidad de Suelos & Plantas UVIGO, Unidad Asociada MBG CSIC, Vigo, 36310, Spain. rsantiago@uvigo.es.|Dept. Biología Vegetal & Ciencias Suelo, Facultad de Biología, Campus Lagoas Marcosende, Vigo, 36310, Spain. rsantiago@uvigo.es.
authors.forename: Rogelio
authors.identifier: 0000-0001-5036-3975
authors.initials: R
authors.lastname: Santiago
authors.affiliation: Universidad de Vigo, Agrobiología Ambiental Calidad de Suelos & Plantas UVIGO, Unidad Asociada MBG CSIC, Vigo, 36310, Spain.|Misión Biológica de Galicia CSIC, Apartado 28, Pontevedra, 36080, Spain.|Dept. Biología Vegetal & Ciencias Suelo, Facultad de Biología, Campus Lagoas Marcosende, Vigo, 36310, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Cao
authors.affiliation: Misión Biológica de Galicia CSIC, Apartado 28, Pontevedra, 36080, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Butrón
authors.affiliation: Universidad de Vigo, Agrobiología Ambiental Calidad de Suelos & Plantas UVIGO, Unidad Asociada MBG CSIC, Vigo, 36310, Spain.|Dept. Biología Vegetal & Ciencias Suelo, Facultad de Biología, Campus Lagoas Marcosende, Vigo, 36310, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: López-Malvar
authors.affiliation: Misión Biológica de Galicia CSIC, Apartado 28, Pontevedra, 36080, Spain.
authors.forename: Víctor M
authors.initials: VM
authors.lastname: Rodríguez
authors.affiliation: The Genome Center and Department Plant Sciences, University of California, Davis - USDA-ARS. 1636 E. Alisal St., Salinas, CA, 93905, USA.
authors.forename: Germán V
authors.initials: GV
authors.lastname: Sandoya
authors.affiliation: Misión Biológica de Galicia CSIC, Apartado 28, Pontevedra, 36080, Spain.
authors.forename: Rosa A
authors.initials: RA
authors.lastname: Malvar
mesh_terms: D000818:Animals; D001572:Benzofurans / Q000378:metabolism; D048588:Benzoxazines / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D003373:Coumaric Acids / Q000378:metabolism; D005838:Genotype; D060434:Herbivory; D007814:Larva; D009036:Moths / Q000502:physiology; D018515:Plant Leaves / Q000502:physiology*; D003313:Zea mays / Q000235:genetics / Q000502:physiology*
chemical_list: D001572:Benzofurans; D048588:Benzoxazines; D003373:Coumaric Acids; C050733:2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one
keywords: Cell wall hydroxycinnamates; DIMBOA; Induced response; Maize antibiosis; Oral secretions