NATURAL GENETIC-TRANSFORMATION BY AGROBACTERIUM-RHIZOGENES - ANNUAL FLOWERING IN 2 BIENNIALS, BELGIAN-ENDIVE AND CARROT

Genetic transformation of Belgian endive (Cichorium intybus) and carro t (Daucus carota) by Agrobacterium rhizogenes resulted in a transforme d phenotype, including annual flowering. Backcrossing of transformed ( R-1) endive plants produced a line that retained annual flowering in t he absence of the other traits associated with A. rhizogenes transform ation. Annualism was correlated with the segregation of a truncated tr ansferred DNA (T-DNA) insertion. During vegetative growth, carbohydrat e reserves accumulated normally in these annuals, and they were proper ly mobilized prior to anthesis. The effects of individual root-inducin g left-hand T-DNA genes on flowering were tested in carrot, in which r olC (root locus) was the primary promoter of annualism and rolD caused extreme dwarfism. We discuss the possible adaptive significance of th is attenuation of the phenotypic effects of root-inducing left-hand T- DNA.