DIFFERENCES IN SUSCEPTIBILITY OF ARABIDOPSIS ECOTYPES TO CROWN GALL DISEASE MAY RESULT FROM A DEFICIENCY IN T-DNA INTEGRATION

We show that among ecotypes of Arabidopsis, there is considerable vari ation in their susceptibility to crown gall disease. Differences in su sceptibility are heritable and, in one ecotype, segregate as a single major contributing locus. In several ecotypes, recalcitrance to tumori genesis results from decreased binding of Agrobacterium to inoculated root explants. The recalcitrance of another ecotype occurs at a late s tep in T-DNA transfer. Transient expression of a T-DNA-encoded beta-gl ucuronidase gusA gene is efficient? but the ecotype is deficient in cr own gall tumorigenesis, transformation to kanamycin resistance, and st able GUS expression. This ecotype is also more sensitive to gamma radi ation than is a susceptible ecotype. DNA gel blot analysis showed that after infection by Agrobacterium, less T-DNA was integrated into the genome of the recalcitrant ecotype than was integrated into the genome of a highly susceptible ecotype.