Effects of the introduction of Agrobacterium rhizogenes rol genes on tomato plant and flower development

Individual rol genes of the Ri-plasmid of Agrobacterium rhizogenes were introduced into tomato (Lycopersicon esculentum Mill.) to study their effects on plant growth and development. Punctured cotyledon transformations were carried out to obtain tomato plants transgenic for the T-DNA genes rolA, rolB and rolABC, which are involved in hairy root formation. Regenerated plants showed characteristic phenotypes, specific for the different rol genes. Transgenic RolA plants manifested a severe wrinkling of leaves, a reducted flower bud length, hyperstyly and decreased pollen viability. The RolB plants were characterized by a reduction in both internode length and apical dominance. The phenotypic expressions of rolA and rolB genes were not observed in RolABC plants, suggesting antagonistic effects. Root formation was induced rather easily on leaf explants from eitheir RolA, RolA or RolABC tomato plants on medium containing auxin. Pollen of transformed RolA and RolB plants also showed an increased auxin sensitivity.