Stable transformation of alfalfa (Medicago sativa L.) by particle bombardment.

Stable transformation of alfalfa (Medicago sativa L.) was obtained by particle bombardment of calli (derived from petiole and stem sections cultured for three weeks on SH medium), followed by delayed selection with 50 mg/l kanamycin on BOi2Y medium. Selection at a lower level of kanamycin (25 mg/l) in late stages of culture resulted only in escapes. Analysis of seven transgenic plants revealed that all were derived from one transformation event. Segregation of the neomycin phosphotransferase gene in test cross progeny followed a 1∶1 Mendelian ratio for a single locus insertion in a heterozygous state.