title: Allium sativum produces terpenes with fungistatic properties in response to infection with Sclerotium cepivorum.
abstract: This study investigated terpene biosynthesis in different tissues (root, protobulb, leaf sheath and blade) of in vitro-grown garlic plants either infected or not (control) with Sclerotium cepivorum, the causative agent of Allium White Rot disease. The terpenes identified by gas chromatography-electron impact mass spectrometry (GC-EIMS) in infected plants were nerolidol, phytol, squalene, α-pinene, terpinolene, limonene, 1,8-cineole and γ-terpinene, whose levels significantly increased when exposed to the fungus. Consistent with this, an increase in terpene synthase (TPS) activity was measured in infected plants. Among the terpenes identified, nerolidol, α-pinene and terpinolene were the most abundant with antifungal activity against S. cepivorum being assessed in vitro by mycelium growth inhibition. Nerolidol and terpinolene significantly reduced sclerotia production, while α-pinene stimulated it in a concentration-dependent manner. Parallel to fungal growth inhibition, electron microscopy observations established morphological alterations in the hyphae exposed to terpinolene and nerolidol. Differences in hyphal EtBr uptake suggested that one of the antifungal mechanisms of nerolidol and terpinolene might be disruption of fungal membrane integrity.
authors.affiliation: Estación Experimental Agropecuaria La Consulta-Instituto Nacional de Tecnología Agropecuaria, CC8, 5567 La Consulta, Mendoza, Argentina; Laboratorio de Bioquímica Vegetal, Instituto de Biología Agrícola de Mendoza, Consejo Nacional de Investigaciones Científicas y Tecnológicas-Universidad Nacional de Cuyo, Almirante Brown 500, M5528AHB Chacras de Coria, Mendoza, Argentina. Electronic address: pontin.mariela@inta.gob.ar.
authors.forename: Mariela
authors.initials: M
authors.lastname: Pontin
authors.affiliation: Laboratorio de Bioquímica Vegetal, Instituto de Biología Agrícola de Mendoza, Consejo Nacional de Investigaciones Científicas y Tecnológicas-Universidad Nacional de Cuyo, Almirante Brown 500, M5528AHB Chacras de Coria, Mendoza, Argentina. Electronic address: rbottini@fca.uncu.edu.ar.
authors.forename: Rubén
authors.initials: R
authors.lastname: Bottini
authors.affiliation: Estación Experimental Agropecuaria La Consulta-Instituto Nacional de Tecnología Agropecuaria, CC8, 5567 La Consulta, Mendoza, Argentina. Electronic address: burba.jose@gmail.com.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Burba
authors.affiliation: Laboratorio de Bioquímica Vegetal, Instituto de Biología Agrícola de Mendoza, Consejo Nacional de Investigaciones Científicas y Tecnológicas-Universidad Nacional de Cuyo, Almirante Brown 500, M5528AHB Chacras de Coria, Mendoza, Argentina. Electronic address: ppiccoli@fca.uncu.edu.ar.
authors.forename: Patricia
authors.initials: P
authors.lastname: Piccoli
mesh_terms: D000935:Antifungal Agents / Q000032:analysis* / Q000737:chemistry; D001203:Ascomycota; D001487:Basidiomycota / Q000187:drug effects / Q000472:pathogenicity*; D000081008:Bicyclic Monoterpenes; D000081005:Cyclohexane Monoterpenes; D003511:Cyclohexanols; D053138:Cyclohexenes; D000077591:Eucalyptol; D005737:Garlic / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D000077222:Limonene; D039821:Monoterpenes; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry; D012717:Sesquiterpenes; D013729:Terpenes
chemical_list: D000935:Antifungal Agents; D000081008:Bicyclic Monoterpenes; D000081005:Cyclohexane Monoterpenes; D003511:Cyclohexanols; D053138:Cyclohexenes; D039821:Monoterpenes; D012717:Sesquiterpenes; D013729:Terpenes; C018669:gamma-terpinene; D000077222:Limonene; C005451:alpha-pinene; C027009:terpinolene; C037055:nerolidol; D000077591:Eucalyptol
keywords: Allium sativum; Amaryllidaceae; Antifungal activity; Garlic; Hyphal morphology; Sclerotium cepivorum; Terpenes; White Rot disease