Mannitol and thidiazuron improve in vitro shoot regeneration from spearmint and peppermint leaf disks

In vitro shoot organogenesis of peppermint and spearmint was obtained from leaf disks. Regeneration occurred within six weeks of placement in culture. Best results were obtained when explants were cultured for two weeks onto Murashige and Skoog medium supplemented with 300 mM mannitol, 2.0 mu M 6-benzyladenine and 2.0 mu M indole-3-butyric acid, and then transferred on a medium without mannitol and containing 0.5 mu M cr-naphthaleneacetic acid, 9.0 mu M 6-benzyladenine and 0.5 mu M thidiazuron. Using these culture conditions, percentages of regeneration were 78% for peppermint and 49% for spearmint. Because of its efficiency, this leaf disk regeneration method could be a suitable tool for genetic transformation with Agrobacterium tumefaciens.