TRANSLOCATION AND EXUDATION OF TUMOR METABOLITES IN CROWN GALLED PLANTS

Crown gall tumors are induced on susceptible plane by pathogenic strai ns of Agrobacterium. These neoplastic plant cells produce metabolites, called opines, which provide a source of nutrients to colonizing agro bacteria. Opine production previously has been shown to influence micr obial communities in the immediate vicinity of the tumor. We have obta ined evidence for opine translocation to and exudation from distal uni nfected regions of the plant host, Grafted plants made from an opine-p roducing transgenic scion with a wild-type stock, or with a wild-type scion and an opine-producing stock accumulate opines in the wild-type portions of the plant. Moreover, opines were detected in root, stem, a nd leaf tissues of nontransgenic plants on which stem crown galls had been induced by pathogenic strains of Agrobacterium. These plants exud ed opines from their roots as a component of their root exudates. Tran slocation of opines from the tumor to other parts of the plant, and th eir exudation from roots, indicates that these biologically active com pounds are available to opine-catabolizing microbes that have not indu ced the tumors but are present in the rhizosphere or on portions of th e plant distant from the site of the gall.