title: Volatile organic compounds from rhizobacteria increase biosynthesis of essential oils and growth parameters in peppermint (Mentha piperita).
abstract: Volatile organic compounds (VOCs), characterized by low molecular weight and high vapor pressure, are produced by all organisms as part of normal metabolism, and play important roles in communication within and between organisms. We examined the effects of VOCs released by three species of plant growth-promoting rhizobacteria (Pseudomonas fluorescens, Bacillus subtilis, Azospirillum brasilense) on growth parameters and composition of essential oils (EO) in the aromatic plant Mentha piperita (peppermint). The bacteria and plants were grown on the same Petri dish, but were separated by a physical barrier such that the plants were exposed only to VOCs but not to solutes from the bacteria. Growth parameters of plants exposed to VOCs of P. fluorescens or B. subtilis were significantly higher than those of controls or A. brasilense-treated plants. Production of EOs (monoterpenes) was increased 2-fold in P. fluorescens-treated plants. Two major EOs, (+)pulegone and (-)menthone, showed increased biosynthesis in P. fluorescens-treated plants. Menthol in A. brasilense-treated plants was the only major EO that showed a significant decrease. These findings suggest that VOCs of rhizobacteria, besides inducing biosynthesis of secondary metabolites, affect pathway flux or specific steps of monoterpene metabolism. Bacterial VOCs are a rich source for new natural compounds that may increase crop productivity and EO yield of this economically important plant species.
authors.affiliation: Dpto. Biología Molecular, FCEFQyN, Universidad Nacional de Río Cuarto, Campus Universitario, 5800 Río Cuarto, Argentina.
authors.forename: Maricel Valeria
authors.initials: MV
authors.lastname: Santoro
authors.forename: Julio
authors.initials: J
authors.lastname: Zygadlo
authors.forename: Walter
authors.initials: W
authors.lastname: Giordano
authors.forename: Erika
authors.initials: E
authors.lastname: Banchio
mesh_terms: D015806:Azospirillum brasilense / Q000737:chemistry; D001412:Bacillus subtilis / Q000737:chemistry; D053898:Biosynthetic Pathways / Q000187:drug effects; D003470:Culture Media; D046508:Culture Techniques; D000081005:Cyclohexane Monoterpenes; D036142:Mentha piperita / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D008610:Menthol / Q000378:metabolism; D039821:Monoterpenes / Q000378:metabolism; D009822:Oils, Volatile / Q000378:metabolism*; D011551:Pseudomonas fluorescens / Q000737:chemistry; D055549:Volatile Organic Compounds / Q000494:pharmacology*
chemical_list: D003470:Culture Media; D000081005:Cyclohexane Monoterpenes; D039821:Monoterpenes; D009822:Oils, Volatile; D055549:Volatile Organic Compounds; D008610:Menthol; C054487:menthofuran; C039648:pulegone; C019466:menthone