Genetic instability in protoclones of potato (Solanum tuberosum L. cv. 'Bintje'): new types of variation after vegetative propagation.

The transmission of variation from protoplast-derived plants of tetraploid potato cultivar 'Bintje' to tuber progeny was examined. The morphological alterations of a majority of the variant protoclones were transmitted to corresponding tuber progeny. Some of the normal and variant protoclones gave new phenotypes, or segregated into parental and new phenotypes after vegetative propagation. The ploidy levels of almost all these clones remained unchanged after propagation. It was concluded that the occurrence of variation after vegetative propagation was due to somatic segregation of chimeras resulting from gene mutations or chromosome structural rearrangements in only part of the regenerated plant. The origin of variation is discussed in the light of these results.