A novel technique for Musa acuminata Colla 'Grand Naine' (AAA) micropropagation through transverse sectioning of the shoot apex

A new approach is described for in vitro shoot proliferation using transverse sections of individual shoot apices as explants, and its efficiency was compared to conventional shoot apex culture of banana 'Grand Naine'. Individual shoot apex explants were inoculated on Murashige and Skoog (MS) media supplemented with 0, 10, 20, and 30 mu M of 6-benzylaminopurine (BAP) in combination with 1.0 mu M alpha-naphthaleneacetic acid (NAA) and maintained for 6 mo with monthly subculture. Shoot proliferation increased at each subculture to a maximum of 23.65 shoots on 20 mu M BAP-supplemented medium. To increase the proliferation rate, individual shoot apices cultured on MS media containing 10 mu M BAP were split into three transverse sections, and the middle section produced the highest number of shoots (7.22). These shoots, when cultured on MS medium supplemented with 20 mu M BAP, produced 8.26 shoots per explant vs. 6.18 and 7.94, respectively, for media supplemented with BAP at 10 or 30 mu M. From just one transverse section, 32.77 shoots could be produced after 6 mo vs. 11.79 shoots via direct regeneration from individual shoot apex explants. MS medium supplemented with 6 mu M IBA induced vigorous rooting within 4 wk. Acclimatization was achieved under greenhouse conditions, and the highest survival rate was 88.63%. Randomly amplified polymorphic DNA (RAPD) analysis showed that plants from shoot apex cultures had 23.46% polymorphism, while those from transverse sections showed no genetic variation when compared to the parent plants.