Direct regenerationin vitro and transient GUS expression inMentha xpiperita.

ABSTRACT

Genetic transformation of peppermint is known to be very difficult essentially because of low efficiency regeneration. A regeneration protocol allowing 51% shooting frequency is proposed. Transient ß-glucuronidase expression and adjustment of selection pressure with kanamycin are also reported. The final retained method to attempt peppermint transformation isAgrobacterium inoculation or biolistic treatment of the first apical leaves ofin vitro clones, regeneration in the dark with kanamycin (1 mg l(-1)) and 6-benzylaminopurine (2 mg l(-1)), followed by selection of regenerated shoots with 200 mg 1(-1) kanamycin.