Ploidy levels in leaf callus and regenerated plants of Solanum tuberosum determined by cytophotometric measurements of protoplasts

Abstract

In potato (Solanum tuberosum) instabilities in nuclear DNA content in callus cells of a monohaploid and a dihaploid and in tuberprogenies of a regenerated, doubled dihaploid plant were assessed by cytophotometry in isolated, purified protoplasts. Leaf protoplasts of a tetraploid variety have nuclei with 3.6±0.08 pg of DNA. In callus protoplasts a dihaploid showed 3 and a monohaploid 6 ploidy levels. Progeny of a plant, doubled and regenerated from dihaploid callus, showed mixo-euploidy, indicating an instability similar to the dihaploid callus; in addition, there are mixo-aneuploid cells.These findings confirm and extend earlier observations based on chromosome counts in other genotypes of potato. The experimental approach can be applied to a variety of other purposes.

Regeneration of Plants from Potato Protoplasts

“…Reports exist, however, of similar expressions of somaclonal variations produced during the raising of calli directly from walled somatic cells (Behnke 1979(Behnke , 1980Jacobsen 1981;Austin and Cassells 1983;Cassels et al 1983;Jacobsen et al 1983;Karp et al 1984). There is no a priori reason for assuming that protoplast-produced variants are different in nature from those that result from callus culture.…”

Increased frost tolerance and amino acid content in leaves, tubers and leaf callus of regenerated hydroxyproline resistant potato clones

“…They partly reflect karyotypic irregularities found in cell cultures of the potato clone used in this study (PIJNACKER et al, 1986) or in other diploid clones (SEE RAMULU et al, 1985). Hypotetraploid regenerants from diploid cell cultures of potato have been reported before (JACOBSEN, 1981, 1986a, 1986b, JACOBSEN et al, 1983.…”

“…At our laboratory a good fertile diploid potato clone was selected for its capacity to proliferate vigorously in cell culture and to regenerate even after more than 1 year in culture (JACOBSEN et al, 1983). From this cell culture several amino acid analogue resistant lines have been selected and resistant shoots were regenerated in some cases (JACOBSEN, 1986a).…”

Development of amylose-free (amf) monoploid potatoes as new basic material for mutation breeding in vitro

“…After emergence the plantlets with 'nodal bands', controlled by the same gene as the embryo-spot marker, were removed (Uijtewaal et al, 1987). In non-hybrid seedlings without a nodal band, the ploidy level was first estimated by counting the number of chloroplasts in the stomatal guard cells after iodine staining (Frandsen, 1968), and later determined by flow cytometry of leaf cells (Jacobsen et al, 1983).…”

“…To monitor the ploidy level accurately, genotypes may be tested by flowcytometry of leaf ceils (Ramulu & Dijkhuis, 1986). By using this method, the level of monoploid cells in the leaves is under-estimated (Jacobsen et al, 1983). This is because a percentage of cells in G1 phase are 1C while the monoploid cells in G2-phase will be found in the 2C peak together with normal diploid cells in Gl-phase.…”