Patent ID: 7173170

Claim:
A method for producing a modified tobacco line comprising an alloploid genome having an altered phenotype of an increased amount of threonine as compared to an unmodified parent alloploid tobacco line comprising the steps of: (a) incubating tobacco seeds in a solution comprising a mutagen; (b) washing the seeds free of the mutagen; (c) germinating the seeds and growing M1 seedlings; (d) adding a medium comprising threonine and lysine to the M1 seedlings; (e) growing the M1 seedlings to generate at least one M1 chimeric plant comprising M2 seeds, wherein the threonine and lysine select for a chimeric M1 plant that at least partially comprises the altered phenotype of an increase in threonine, and wherein the M2 seeds from the chimeric plant comprise non-mutagenized M2 seeds and mutagenized M2 seeds; and (f) germinating the M2 seeds in medium comprising threonine and lysine to select for M2 plants comprising the altered phenotype of an increase of at least a 2 to 150 fold in threonine as compared to the unmodified alloploid parent tobacco line.