title: Terpene down-regulation in orange reveals the role of fruit aromas in mediating interactions with insect herbivores and pathogens.
abstract: Plants use volatile terpene compounds as odor cues for communicating with the environment. Fleshy fruits are particularly rich in volatiles that deter herbivores and attract seed dispersal agents. We have investigated how terpenes in citrus fruit peels affect the interaction between the plant, insects, and microorganisms. Because limonene represents up to 97% of the total volatiles in orange (Citrus sinensis) fruit peel, we chose to down-regulate the expression of a limonene synthase gene in orange plants by introducing an antisense construct of this gene. Transgenic fruits showed reduced accumulation of limonene in the peel. When these fruits were challenged with either the fungus Penicillium digitatum or with the bacterium Xanthomonas citri subsp. citri, they showed marked resistance against these pathogens that were unable to infect the peel tissues. Moreover, males of the citrus pest medfly (Ceratitis capitata) were less attracted to low limonene-expressing fruits than to control fruits. These results indicate that limonene accumulation in the peel of citrus fruit appears to be involved in the successful trophic interaction between fruits, insects, and microorganisms. Terpene down-regulation might be a strategy to generate broad-spectrum resistance against pests and pathogens in fleshy fruits from economically important crops. In addition, terpene engineering may be important for studying the basic ecological interactions between fruits, herbivores, and pathogens.
authors.affiliation: Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias, 46113 Moncada, Valencia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Rodríguez
authors.forename: Victoria
authors.initials: V
authors.lastname: San Andrés
authors.forename: Magdalena
authors.initials: M
authors.lastname: Cervera
authors.forename: Ana
authors.initials: A
authors.lastname: Redondo
authors.forename: Berta
authors.initials: B
authors.lastname: Alquézar
authors.forename: Takehiko
authors.initials: T
authors.lastname: Shimada
authors.forename: José
authors.initials: J
authors.lastname: Gadea
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Rodrigo
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Zacarías
authors.forename: Lluís
authors.initials: L
authors.lastname: Palou
authors.forename: María M
authors.initials: MM
authors.lastname: López
authors.forename: Pedro
authors.initials: P
authors.lastname: Castañera
authors.forename: Leandro
authors.initials: L
authors.lastname: Peña
mesh_terms: D000080462:Acyclic Monoterpenes; D000818:Animals; D033622:Ceratitis capitata / Q000502:physiology*; D032084:Citrus sinensis / Q000187:drug effects / Q000235:genetics / Q000382:microbiology / Q000469:parasitology*; D053138:Cyclohexenes / Q000494:pharmacology; D015536:Down-Regulation / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology; D005638:Fruit / Q000737:chemistry* / Q000187:drug effects / Q000382:microbiology / Q000469:parasitology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D054884:Host-Pathogen Interactions / Q000187:drug effects / Q000235:genetics; D000077222:Limonene; D008297:Male; D008969:Molecular Sequence Data; D009812:Odorants / Q000032:analysis*; D010407:Penicillium / Q000187:drug effects / Q000254:growth & development; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology / Q000469:parasitology; D030821:Plants, Genetically Modified; D013729:Terpenes / Q000378:metabolism* / Q000494:pharmacology; D055549:Volatile Organic Compounds / Q000032:analysis
chemical_list: D000080462:Acyclic Monoterpenes; D053138:Cyclohexenes; D013729:Terpenes; D055549:Volatile Organic Compounds; D000077222:Limonene; C007836:geraniol