Abstract
Chromosome constitutions of callus cells originating from the root of tobacco and from the root and the ovary of wheat were studied. Effects of duration of subculturing and of exogenous substances added to the medium on the chromosome number of callus cells were also studied. In tobacco, the chromosome number in callus cells derived from root tips, subcultured for three to seven months, was predominantly diploid, while in the two year-subcultured callus chromosome numbers varied widely. In common wheat the chromosome constitution of callus cells derived from root tips subcultured for two to four years was similar to that of callus cells from the ovary; in both diploid cells were predominant. The chromosome constitution of callus cells which originated from the root tips of emmer wheat and were maintained on media supplemented with casein hydrolysate was quite similar to those maintained on media containing kinetin, adenine sulfate and 2, 4-D.
