Monogenic Semidominant Sulfonylurea Resistance in a Line of White Chicory

This paper reports on a chlorsulfuron‐resistant line of white chicory (Cichorium intybus cv. ‘Witloof’) regenerated from non‐mutagenized cell cultures. The resistance was inherited as a monogenic semi‐dominant trait. Homozygous resistant individuals withstood doses of herbicide 1500 to 2000‐fold higher than the susceptible ones, whereas this ratio was around 300 for the heterozygotes. Cross‐resistances to seven other sulfonylureas and to one imidazolinone were revealed, leading to the conclusion that this resistance could be due to mutation of the target enzyme.