Patent ID: 8101410

Claim:
A selection marker system for distinguishing genetically modified plant cells from wild-type plant cells during caulogenesis and rhizogenesis comprising (a) a nucleic acid sequence coding for choline oxidase for genetically modifying at least a part of a plant and; (b) at least a part of a wild-type plant of the same plant species, wherein the part of the wild-type plant is a hypocotyl or cotyledonary petiolar explant, wherein the part of the plant which is genetically modified by the nucleic acid sequence coding for choline oxidase is capable of surviving in a medium containing choline at a concentration which is toxic to the wild-type plant, wherein in the part of the wild-type plant caulogenesis is suppressed at a choline concentration of 20-40 mM and/or rhizogenesis is suppressed at a choline concentration of 30-40 mM.