Karyotype variation in aminoethylcysteine resistant cell and callus cultures and regenerated plants of a dihaploid potato (<i>Solanum tuberosum</i>)

Karyotypic studies on cell suspensions and calli of an S-(2-aminoethyl)cysteine resistant cell line of the interdihaploid potato H2578 (2n=24) revealed a high degree of variation in the number of chromosomes (33–217) and dicentric chromosomes (0–8). The suspensions also exhibited megachromosomes and fused chromosomes. Differential staining showed that in suspensions dicentrics survived mitotic cycles mainly by parallel separation of the chromatids during anaphase and hardly by the breakage-fusion-bridge cycle. Two phenotypes of plantlets regenerated, each with 34 or 35 chromosomes with gross structural mutations and with the triploid amount of DNA. Chromosomal variation was related to the degree of tissue organizatio