Genome selection within cell cultures of potato and tobacco

The ploidy level of callus cultures, suspensions and cell cultures derived from single cells and protoplasts of Solanum tuberosum L. and Nicotania tabascum L. was analysed with the aim of studying selection processes. Genome selection was tested using chromosome number. Subculture of callus lines mostly resulted in an increase of cytogenetic destabilization, whereas subculture of suspensions led to an increase in nuclei which had the ploidy level of stock plants after an initial period of destabilization. During the course of subculture, the development of a dominant ploidy level was observed in some genotypes. In other genotypes, two dominant ploidy levels were found. Furthermore, the narrowing of the confidence interval indicated stabilizing selection. In genotypes showing a high rate of instability, no development of a dominant genome was observed. The in vitro procedure is of decisive importance for genome selection within cell cultures. The interaction between genetic destabilization and genome selection is discussed.