title: Brassinosteroids interact negatively with jasmonates in the formation of anti-herbivory traits in tomato.
abstract: Given the susceptibility of tomato plants to pests, the aim of the present study was to understand how hormones are involved in the formation of tomato natural defences against insect herbivory. Tomato hormone mutants, previously introgressed into the same genetic background of reference, were screened for alterations in trichome densities and allelochemical content. Ethylene, gibberellin, and auxin mutants indirectly showed alteration in trichome density, through effects on epidermal cell area. However, brassinosteroids (BRs) and jasmonates (JAs) directly affected trichome density and allelochemical content, and in an opposite fashion. The BR-deficient mutant dpy showed enhanced pubescence, zingiberene biosynthesis, and proteinase inhibitor expression; the opposite was observed for the JA-insensitive jai1-1 mutant. The dpy x jai1-1 double mutant showed that jai1-1 is epistatic to dpy, indicating that BR acts upstream of the JA signalling pathway. Herbivory tests with the poliphagous insect Spodoptera frugiperda and the tomato pest Tuta absoluta clearly confirmed the importance of the JA-BR interaction in defence against herbivory. The study underscores the importance of hormonal interactions on relevant agricultural traits and raises a novel biological mechanism in tomato that may differ from the BR and JA interaction already suggested for Arabidopsis.
authors.affiliation: Departamento de Ciências Biológicas, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba-SP, Brazil.
authors.forename: Marcelo Lattarulo
authors.initials: ML
authors.lastname: Campos
authors.forename: Marcílio
authors.initials: M
authors.lastname: de Almeida
authors.forename: Mônica Lanzoni
authors.initials: ML
authors.lastname: Rossi
authors.forename: Adriana Pinheiro
authors.initials: AP
authors.lastname: Martinelli
authors.forename: Celso Gaspar
authors.initials: CG
authors.lastname: Litholdo Junior
authors.forename: Antonio
authors.initials: A
authors.lastname: Figueira
authors.forename: Fátima Teresinha
authors.initials: FT
authors.lastname: Rampelotti-Ferreira
authors.forename: José Djair
authors.initials: JD
authors.lastname: Vendramim
authors.forename: Vagner Augusto
authors.initials: VA
authors.lastname: Benedito
authors.forename: Lázaro Eustáquio Pereira
authors.initials: LE
authors.lastname: Peres
mesh_terms: D000818:Animals; D003517:Cyclopentanes / Q000378:metabolism*; D004435:Eating; D018506:Gene Expression Regulation, Plant; D007313:Insecta / Q000502:physiology*; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism*; D054883:Oxylipins / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D019655:Quantitative Trait, Heritable
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; D010937:Plant Growth Regulators; C011006:jasmonic acid