Rhizogenic agrobacteria as an innovative tool for plant breeding: current achievements and limitations

Compact plant growth is an economically important trait for many crops. In practice, compactness is frequently obtained by
applying chemical plant growth regulators. In view of sustainable and environmental-friendly plant production, the search for
viable alternatives is a priority for breeders. Co-cultivation and natural transformation using rhizogenic agrobacteria result in
morphological alterations which together compose the Ri phenotype. This phenotype is known to exhibit a more compact plant
habit, besides other features. In this review, we highlight the use of rhizogenic agrobacteria and the Ri phenotype with regard to
sustainable plant production and plant breeding. An overviewof described Ri lines and current breeding applications is presented.
The potential of Ri lines as pre-breeding material is discussed from both a practical and legal point of view.