Improvement of plant regeneration from long-term cultured calluses of Taipei 309, a model rice variety in in vitro studies

Abstract

An efficient protocol was developed for regeneration of plants from long-term cultured calluses, which originated from mature seeds of a model rice variety Taipei 309 and were maintained by subculture for at least 6 months. The calluses were precultured for 4 weeks on a medium containing 8.88 μmol 6-benzyladenine, 5.37 μmol α-naphthaleneacetic acid and various concentrations of abscisic acid, which converted the calluses to a state more responsive to the subsequent culture conditions for plant regeneration. Supplementation of 8.69 mmol proline in the preculture medium increased the growth rate of the callus masses by 50% and resulted in the regeneration of 60% more plants. A more pronounced effect was observed after raising the 6-benzyladenine concentration to 55.48 μmol in the preculture medium, which promoted the development of adventitious buds on the calluses and led to the regeneration of some 30% more plants of better quality. Results indicate that manipulation of medium supplements and growth regulators leads to efficient plant regeneration in long-term callus cultures of rice.