PLANT-REGENERATION FROM LONG-TERM CALLUS-CULTURE OF AAA-GROUP DESSERTBANANA

The banana plant is one of the most widely cultivated crops in the wor ld. However, banana breeding has been a slow process, due to the low s eed set and low germination rates. Selection of useful somaclonal vari ations and genetic transformation in cells or calluses are promising t echniques to accelerate the breeding process. Therefore, callus cultur e was carried out, aiming the establishment of one protocol for plant regeneration, to be used in banana breeding program. Leaf sheath disks of 'Nanicao' banana (Musa sp., AAA group, Cavendish subgroup) were cu ltured on a Murashige and Skoog (MS) basal medium supplemented with ac tivated charcoal (0.2%), MES (2 [N-morpholino] ethanesulfonic acid) (1 5.3 mM), arginine (300 mM), Picloram (414 mu M) and 2iP (2-isopentenyl adenine) (492 mu M). Globular calluses developed on the leaf tissue w ere subcultured in the same medium, acquiring a friable and translucid appearance after one and a half year of culture. The friable calluses were transferred to the medium without growth regulators and arginine , and supplemented with casein hydrolysate (0.05%), where they formed embryo-like structures after transference to light. From these structu res, shoots with roots were obtained and plantlets developed. The plan t regeneration protocol shown here may be useful to banana breeding vi a somaclonal variation.