title: Transformed hairy roots of Discaria trinervis: a valuable tool for studying actinorhizal symbiosis in the context of intercellular infection.
abstract: Among infection mechanisms leading to root nodule symbiosis, the intercellular infection pathway is probably the most ancestral but also one of the least characterized. Intercellular infection has been described in Discaria trinervis, an actinorhizal plant belonging to the Rosales order. To decipher the molecular mechanisms underlying intercellular infection with Frankia bacteria, we set up an efficient genetic transformation protocol for D. trinervis based on Agrobacterium rhizogenes. We showed that composite plants with transgenic roots expressing green fluorescent protein can be specifically and efficiently nodulated by Frankia strain BCU110501. Nitrogen fixation rates and feedback inhibition of nodule formation by nitrogen were similar in control and composite plants. In order to challenge the transformation system, the MtEnod11 promoter, a gene from Medicago truncatula widely used as a marker for early infection-related symbiotic events in model legumes, was introduced in D. trinervis. MtEnod11::GUS expression was related to infection zones in root cortex and in the parenchyma of the developing nodule. The ability to study intercellular infection with molecular tools opens new avenues for understanding the evolution of the infection process in nitrogen-fixing root nodule symbioses.
authors.affiliation: Departamento de Ciencia y Tecnologia, Universidad Nacional de Quilmes, Bernal, Argentina.
authors.forename: Leandro
authors.initials: L
authors.lastname: Imanishi
authors.forename: Alice
authors.initials: A
authors.lastname: Vayssières
authors.forename: Claudine
authors.initials: C
authors.lastname: Franche
authors.forename: Didier
authors.initials: D
authors.lastname: Bogusz
authors.forename: Luis
authors.initials: L
authors.lastname: Wall
authors.forename: Sergio
authors.initials: S
authors.lastname: Svistoonoff
mesh_terms: D060054:Agrobacterium / Q000502:physiology*; D046913:Medicago truncatula / Q000235:genetics; D009586:Nitrogen Fixation; D018517:Plant Roots / Q000382:microbiology*; D030821:Plants, Genetically Modified; D027823:Rhamnaceae / Q000382:microbiology*; D013559:Symbiosis; D014170:Transformation, Genetic