INITIATION AND MAINTENANCE OF FRIABLE, EMBRYOGENIC CALLUS OF SORGHUM (SORGHUM-BICOLOR (L) MOENCH) BY AMINO-ACIDS

The simultaneous addition of asparagine and proline in high concentrations (1-3 g/l) to the culture media (MS or Nb), containing 2,4-D, increases the proliferation of sorghum embryogenic callus and diminishes the production of toxic pigment specific to sorghum tissue cultures. The friable embryogenic callus (FEC) appears in the cultures being grown on Nb medium with addition of these amino acids. On this medium FEC develops both in the prime cultures of immature embryos and from the compact embryogenic calli obtained by the usual procedure from mature embryos and young panicles on 2,4-D-cytokinin-containing media. The established FEC lines were able for active proliferation for more than 1.5-2.0 years. The cultivars belonging to the subglabrescens/milo group of Sorghum bicololr (L.) Moench possess the highest ability to FEC formation. The environmental factors significantly influence FEC formation from immature embryos. Plantlets have been regenerated from FEC of all four tested cultivars, however, regenerative potential decreased during subculturing.