Bud regeneration from Eucalyptus globulus clones and seedlings through hormonal imbalances induced by Agrobacterium tumefaciens strain 82.139

Bud regeneration from seedling hypocotyls and stem cuttings arising from micropropagated plantlets of Eucalyptus globulus was achieved using inoculation with the wild Agrobacterium tumefaciens strain 82.139 which induced shooty tumors. The adventitious buds regenerated on the shooty tumors were untransformed as revealed by the use of a C58pMP90/T139GUS-INT strain harbouring the intron inactivated uidA (gus) reporter gene. Subsequent rooting and acclimatization were achieved for some of the regenerants. Flow cytometric analyses of nuclear DNA contents indicated that both the tumors and the regenerants were diploid. Endogenous hormone quantification was performed in shooty and non shooty tumors induced by strains 82.139 and C58, respectively. The shooty potential of the strain 82.139 was associated with high Z and ZR levels in the tumors while auxin levels were similar in shooty and non shooty tumors. The efficiency of the method could be useful for both regeneration and genetic transformation from organs of cloned E. globulus. (C) 1997 Elsevier Science Ireland Ltd.