DisplayTitle

Virulence Genes of the Phytopathogen Rhodococcus fascians Show Specific Spatial and Temporal Expression Patterns During Plant Infection

¹Vakgroep Moleculaire Genetica, Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie (VIB), Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium; ²Laboratoire de Biotechnologie Végétale, Université Libre de Bruxelles, Chaussée de Wavre 1850, B-1160 Brussels, Belgium

The phytopathogenic bacterium Rhodococcus fascians provokes shoot meristem formation and malformations on aerial plant parts, mainly at the axils. The interaction is accompanied by bacterial colonization of the plant surface and tissues. Upon infection, the two bacterial loci required for full virulence, fas and att, were expressed only at the sites of symptom development, although their expression profiles differed both spatially and temporally. The att locus was expressed principally in bacteria located on the plant surface at early stages of infection. Expression of the fas locus occurred throughout infection, mainly in bacteria that were penetrating, or had penetrated, the plant tissues and coincided with sites of meristem initiation and proliferation. The implications for the regulation of virulence genes of R. fascians during plant infection are discussed.

Additional keywords: GUS fusion , histochemical analysis.