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

Philipp Rüter, Thomas Debener, Traud Winkelmann

Oral presentation

The ‘RootsPlus’ project is a European collaboration between research institutions in Belgium, Germany, Poland and Romania and two companies. Natural transformation with Rhizobium rhizogenes wildtype strains shall be developed as a new breeding technology for apple, chrysanthemum, sunflower and rose.

Rhizobium rhizogenes contains a unique Ri plasmid, that allows it to transfer and integrate its T-DNA into the plant genome. The integrated genes lead to the development of an enhanced root formation, so called “hairy roots”. Subsequently, Ri plants can be regenerated from these roots in vitro. The presence of the Ri genes results in a typical phenotype with a more pronounced root system and more compact growth, as well as changes in flowering and leaf morphology. In many countries, for these natural transformants the regulations for GMOs (genetically modified organisms) do not apply.

The major objective of this study is to investigate the genetic basis of transformability in rose. Using a GWAS (genome-wide association study), genes and genomic regions will be identified that are important for transformability by R. rhizogenes. For a panel of 105 cut and garden roses the genotypic data is already present in form of the 68k Axiom WagRhSNP chip. Per genotype, thirty in vitro leaf explants were transformed in two repetitions with a bacterial strain carrying the reporter gene GFP (green fluorescent protein) and thus delivered the phenotypic data by counting of fluorescent hairy roots. Peaks were detected in genomic regions, that co-localize with genes, that are already known for their importance for adventitious root formation. In addition, peaks in other genomic regions were identified which do not seem to have a direct connection to root formation. These will be evaluated for SNPs with significant effects and the underlying genes, since they are expected to contain crucial factors for the transformation process itself.