title: Monitoring the plant epiphyte Methylobacterium extorquens DSM 21961 by real-time PCR and its influence on the strawberry flavor.
abstract: Besides its influence on plant growth and health, plant-associated bacteria exert an impact on fruit quality. Methylotrophic bacteria can enhance the biosynthesis of strawberry flavor compounds, especially the two furanoid compounds 2,5-dimethyl-4-hydroxy-2H-furanone (DMHF) and 2,5-dimethyl-4-methoxy-2H-furanone in vitro. Here, we report the selection and characterization of Methylobacterium extorquens DSM 21961, a strain that was able to enhance the furanone content ad planta under greenhouse conditions. For monitoring the colonization of strawberry plants, a strain-specific quantification system for M. extorquens DSM 21961 was developed. Specificity, linear range and quantitative limit of the system were shown, and successful application was demonstrated in a monitoring experiment of M. extorquens DSM 21961 on strawberry leaves under greenhouse conditions. Furthermore, the quantification of DMHF in strawberry fruits via GC indicated an increased biosynthesis of this compound in strawberry plants. The colonization behavior analyzed by confocal laser scanning microscopy using GFP-tagged cells revealed high colonization of the upper and the lower leaf surfaces, with a specific accumulation of bacterial cells on trichomes. The results support a biotechnological application of this promising flavor-stimulating agent.
authors.affiliation: Institute of Environmental Biotechnology, Graz University of Technology, Graz, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Verginer
authors.forename: Barbara
authors.initials: B
authors.lastname: Siegmund
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Cardinale
authors.forename: Henry
authors.initials: H
authors.lastname: Müller
authors.forename: Young
authors.initials: Y
authors.lastname: Choi
authors.forename: Carlos B
authors.initials: CB
authors.lastname: Míguez
authors.forename: Erich
authors.initials: E
authors.lastname: Leitner
authors.forename: Gabriele
authors.initials: G
authors.lastname: Berg
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D002849:Chromatography, Gas; D004269:DNA, Bacterial / Q000302:isolation & purification; D031985:Fragaria / Q000378:metabolism* / Q000382:microbiology; D005663:Furans / Q000378:metabolism*; D057230:Limit of Detection; D020601:Methylobacterium extorquens / Q000254:growth & development* / Q000302:isolation & purification; D018613:Microscopy, Confocal; D018515:Plant Leaves / Q000382:microbiology; D016133:Polymerase Chain Reaction
chemical_list: D004269:DNA, Bacterial; D005663:Furans; C514184:4-methoxy-2,5-dimethyl-3(2H)-furanone; C058427:furaneol; D015107:4-Butyrolactone