Germ line genetic transformation in cotton (Gossypium hirsutum L.) by selection of transgenic meristematic cells with a herbicide molecule

Imazapyr is a herbicide molecule that when applied, concentrates in the apical meristematic region of plants. It inhibits the activity of acetohydroxyacid synthase, the enzyme that catalyzes the initial step in biosynthesis of isoleucine, leucine and valine. Previously isolated from Arabidopsis thaliana, the selectable marker gene, ahas, contains a mutation at position 653. Using a combination of imazapyr, the ahas gene, and a multiple shoot induction protocol, we have developed a novel system to select transgenic cotton meristematic cells after the physical introduction of foreign genes. In the present study, we describe the protocol for obtaining germ line transformation of Brazilian cotton varieties (var. 7MH: 0.49%; var. Antares: 0.62%; var. CD-401: 0.71% and var. ITA94: 0.47%).