Establishment of Fine Suspension Cultures of Triticum tauschii ([Coss.] Schmal.) which remain Embryogenic for Several Years

Immature embryos of 10 accessions of Triticum tauschii, the D genome donor of Triticum aestivum, were used to produce embryogenic callus for the initiation of suspension cultures. For the long-term maintenance of embryogenicity of these suspensions, it was necessary to use different media for the initiation, establishment and maintenance phases. The initiation phase required media supplemented with L-proline, L-asparagine and L-glutamine, together with Dicamba at 12 mg L −1 and maltose. In the establishment phase, it was essential to reduce the concentration of Dicamba to 6 mg L −1 for the rapid production of fine suspension cultures. Finally, the long-term maintenance of a capacity for regeneration depended on the inclusion of 1.1 mg L −1 2,4-dichlorophenoxyacetic acid and 30 g L −1 sucrose in the medium. By the use of these procedures, long-term embryogenic fine suspension cultures were established from two accessions, while non-embryogenic fine suspension cultures were produced from five accessions. Over 90% of plants regenerated from fine suspensions of 1-year-old embryogenic cultures were fertile, and embryogenic suspension cultures retained their regeneration capacity for more than 3 years.