In addition to conventional breeding methodologies, including marker-assisted backcross breeding, that led to all rhizomania resistant sugar beet varieties currently in commercial use, various genetic engineering approaches have also been studied for the purpose of further improving disease resistance. These approaches include the pathogen-derived resistance (PDR), relying on the transgenic expression of a key gene from the pathogen, the resistance based on non-viral genes and the RNA silencing-mediated resistance, the most successful variant of PDR.