Patent ID: 7786344

Claim:
A process for preparing transformed plant cells or plant organisms, comprising: a) providing a population of plant cells, the cells containing at least one marker protein, b) transforming said population of plant cells with at least one nucleic acid sequence which imparts an advantageous phenotype to a plant containing it, and i) at least one double-stranded marker protein ribonucleic acid sequence, or ii) an expression cassette or expression cassettes for expressing said at least one double-stranded marker protein ribonucleic acid sequence, wherein the at least one double-stranded marker protein ribonucleic acid sequence or the expression cassette reduces the expression of the at least one marker protein in the plant cells, and wherein the at least one marker protein converts directly or indirectly a substance X which is nontoxic for said population of plant cells into a substance Y which is toxic for said population, c) treating the transformed population of plant cells obtained in step b) with the substance X at a concentration which causes a toxic effect for nontransformed cells due to the conversion by the at least one marker protein, d) selecting transformed plant cells whose genome contains said at least one nucleic acid sequence and which have a growth advantage over nontransformed cells at said concentration of substance X, and optionally e) regenerating a plant organism from the transformed plant cell.