Developing molecular tools for the study of the early steps in the symbiosis Discaria trinervis-Frankia

SVISTOONOFF S; CHARBONNEAU U; VAISSAYRE V; IMANISHI L; BOGUSZ D; FRANCHE C; WALL LG

Bariloche, Argentina

Congreso; 15th International Frankia and Actinorhizal Plants Meeting; 2008

The nitrogen-fixing nodules induced by Frankia in the actinorhizal plant Discaria trinervis result from the intercellular root invasion pathway that implies no root hair deformation and infection (1). In order to develop a procedure for rapid functional analysis of symbiotic genes in Discaria, the biological vector Agrobacterium rhizogenes was tested. This soil pathogen generates adventitious, genetically transformed “hairy roots” resulting from the Ri T-DNA-transfer at the site of inoculation in many dicots, therefore providing a fast and efficient method for producing transgenic roots (2). Two different strains of A. rhizogenes, A4RS (3) and ARqua1 (4), carrying a 35S-GFP construct were tested on Discaria. Plants were transformed in vitro as in (5) and ex vitro as in (6). Transgenic roots expressing GFP were obtained for both strains with transformation efficiencies up to 80% for both methods. Roots obtained with ARqua1 are more similar to wild-type roots and are easier to nodulate compared to A4RS. Our data demonstrate that transgenic roots and nodules can be obtained readily in Discaria, thus paving the way for the introduction of gene constructs that will contribute to decipher the early steps of the association with Frankia. This work was financially supported by the Argentinian-French bilateral Project ECOS Sud n°A07B02