title: Systemic induction of monoterpene biosynthesis in Origanumxmajoricum by soil bacteria.
abstract: Italian oregano (Origanumxmajoricum) was subjected to root system inoculation with three species of plant growth-promoting rhizobacteria (PGPRs) (Pseudomonas fluorescens, Bacillus subtilis, Azospirillum brasilense), and essential oil (EO) content and plant growth were measured. Composition of monoterpenes, a major EO component, was analyzed qualitative and quantitatively by gas chromatography. Total EO yield for plants inoculated with P. fluorescens or A. brasilense was 3.57 and 3.41 microg/mg fresh weight, respectively, approximately 2.5-fold higher than controls, without change of quantitative oil composition. The major EO compounds, cis- and trans-sabinene hydrate, gamma-terpinene, carvacrol, and thymol, showed increased biosynthesis. Carvacrol was the only terpene showing significant increase of R% in plants inoculated with A. brasilense. Plant growth parameters (shoot and root fresh and dry weights, numbers of leaves and nodes) were evaluated. Shoot fresh weight was significantly increased by all three PGPR species, but only P. fluorescens and A. brasilense increased root dry weight. These two species have clear commercial potential for economic cultivation of O.xmajoricum. Knowledge of the factors affecting yield and accumulation of monoterpenes is essential for improving production of these economically important plant compounds.
authors.affiliation: Department Biologia Molecular, FCEFQyN, Universidad Nacional de Rio Cuarto, Campus Universitario, 5800 Rio Cuarto, Argentina. ebanchio@exa.unrc.edu.ar
authors.forename: Erika
authors.initials: E
authors.lastname: Banchio
authors.forename: Pablo C
authors.initials: PC
authors.lastname: Bogino
authors.forename: Maricel
authors.initials: M
authors.lastname: Santoro
authors.forename: Lorena
authors.initials: L
authors.lastname: Torres
authors.forename: Julio
authors.initials: J
authors.lastname: Zygadlo
authors.forename: Walter
authors.initials: W
authors.lastname: Giordano
mesh_terms: D015806:Azospirillum brasilense / Q000502:physiology; D001412:Bacillus subtilis / Q000502:physiology; D039821:Monoterpenes / Q000032:analysis / Q000378:metabolism*; D009822:Oils, Volatile / Q000032:analysis; D031341:Origanum / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology*; D018515:Plant Leaves / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D018517:Plant Roots / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D011551:Pseudomonas fluorescens / Q000502:physiology; D012988:Soil Microbiology
chemical_list: D039821:Monoterpenes; D009822:Oils, Volatile