Changes in the organization of the tubulin cytoskeleton during the early stages of Solanum lycopersicoides Dun. protoplast culture.

Changes in the tubulin cytoskeleton during protoplast culture and plant regeneration of Solanum lycopersicoides Dun. were analyzed using an immunodetection method. Directly after isolation, four groups of protoplasts were distinguished: (1) mononuclear, (2) polynuclear, (3) homogeneous, (4) anuclear. The tubulin cytoskeleton of the protoplasts underwent rearrangements, correlating to the number and structure of cell nuclei in the protoplast. All protoplast groups with the exception of mononuclear were characterized by perturbations in the organization of the tubulin cytoskeleton. Anuclear and homogeneous protoplasts did not have a tubulin cytoskeleton. Polynuclear protoplasts had cortical microtubules, but were not capable of re-forming their original arrangement and did not possess a radial or perinuclear cytoskeleton. Irregularities in microtubule arrangement of these three groups of protoplasts caused their inability to regenerate a cell wall and to divide. Anuclear, polynuclear and homogeneous protoplasts were eliminated from the culture. Mononuclear protoplasts rearranged their cortical microtubules and reestablished the radial and perinuclear tubulin cytoskeleton. Re-formation of the cell suspension and subsequent regeneration of plants occurred exclusively from mononuclear protoplasts, which were able to regenerate cell walls and to divide.