The Use of Agrobacterium rhizogenes and its rol-Genes for Quality Improvement in Ornamentals

Agrobacterium rhizogenes and its rol-(root loci)-genes offer the opportunity to introduce new genes for traits contributing to quality improvement in floriculture. Several ornamental plant species have successfully been transformed with rol-genes causing changed root morphology termed root inducing (Ri)-phenotype. The typical Ri-phenotype is a compact plant with a characteristic leaf morphology and improved rooting ability. The Ri-phenotype is due to the effect of the four rol-genes rolA, rolB,, rolC and rolD. These rol-genes are contributing to different morphological effects in the plant. The rol-genes can be introduced all together into the plants by natural transformation using wildtype A. rhizogenes, which presents a transformation method without applying recombinant DNA technology. The rol-genes can also be transferred to a plant as single genes or in different combination by recombinant DNA technology. This makes transformation with A. rhizogenes and its rol-genes a promising method in molecular breeding for creating new diversity in ornamental species. Therefore, the aim of this review paper is to review the uses of A. rhizogenes and its rol-genes for quality improvement in ornamentals.