CROWN GALL RESISTANCE OF VITIS SPP AND GRAPEVINE ROOTSTOCKS

Vitis riparia 'Gloire de Montpellier' (Gloire) was the most resistant Vitis species and clone tested following inoculations with strains of Agrobacterium vitis and A. tumefaciens. Although tumors failed to appe ar after infection, the pathogen A, vitis multiplied at the same rate in Gloire as in the crown gall-susceptible V. vinifera 'Chasselas.' Ro ot decay was induced by strains of A. vitis on all the investigated Vi tis genotypes. Similarly, roots and shoots of all Vitis genotypes prod uced vir gene-inducing compounds. This fact ruled out the possibility that crown gall resistance is related to the lack of vir gene inductio n. However, T-DNA from A. vitis strain CG49 transferred to V. riparia cells at a lower rate than to V. vinifera cells, as determined by eval uation of uidA gene (GUS) expression.