Induction of a virulence response in Agrobacterium tumefaciens by exudatesof Pinus pinea cotyledons

As a preliminary step in efforts to develop a successful protocol for Agrob acterium-mediated transformation of cotyledonary explants of Pinus pinea L. embryos, we tested the ability of embrionary exudates of this species to i nduce the expression of the virulence genes virA, virB, virC, virD, virE an d virG in Agrobacterium tumefaciens containing vir: lacZ fusion constructs. The results obtained in the vir induction assay indicated the absence of b actericidal or bacteriostatic plant compounds affecting A. tumefaciens grow th, and showed that cotyledonary and embrionary exudates of P. pinea are ab le to induce all virulence genes studied, except virG. The data suggest tha t A. tumefaciens can be used for gene transfer into this important forest a nd fruit species.