General Conference abstract: The 27th International Eucarpia Symposium Section Ornamentals, Italy, July 2-5 2023

Ellen De Keyser; Tom Eeckhaut, Jaroslaw Tyburski, Natalia Mucha, Katrijn Van Laere, Emmy Dhooghe

Oral presentation

Climate change and its consequences, we are all aware of it. The urgence to weapon ourselves in the battle against drought is high and plants, also ornamentals, must be bred to withstand longer periods of drought. In this project we use chrysanthemum as a model to develop a new sustainable breeding technology that focuses on the roots, using Rhizobium rhizogenes. Natural strains of Rhizobium rhizogenes contain a unique Ri plasmid (which includes the rol genes) that allows them to transfer and incorporate the T-DNA genes lying on this plasmid into the plant genome. The result is extreme root formation (so called hairy roots). When these roots in turn regenerate into a plant, one obtains Ri plants. The presence of the Ri genes in these plants results in a typical phenotype with a more pronounced root system and more compact growth, as well as changes in flowering and leaf morphology. We want to evaluate the effect of the altered rooting on the drought tolerance of the plants. We will present our results on the creation of the first Ri plants in chrysanthemum, which were fully characterized morphologically as well as genetically. Copy-numbers of the inserted genes as well as the position of these genes on the chromosomes were identified (using digital PCR and FISH, respectively). Since Ri-plants are to be seen as pre-breeding material due to unwanted negative phenotypical features, we will also demonstrate the successful outcrossing of the genes in an F1 and F2 population. Also the outcome of the first experiments on root physiology and the relatedness to drought will be presented.