Regeneration capacity of potato protoplasts isolated from single cell derived donor plants

Protoplast yield, survival, and regeneration was investigated in dihaploid (2n = 2x = 24) clones of potato. These clones consisted of unselected interdihaploids and of microspore or protoplast derived clones, particularly doubled haploids regenerated from the same anther donor clone, androgenetic clones regenerated in a second cycle from androgenetic clones, and protoclones. Significant differences were observed for all characters studied between donor plants without an in vitro history and the other groups, but also within the androgenetic clones, which underlines that they originated from different gametes. Non-significant differences among clones having passed twice through anther culture are indicative of the stability and the homozygosity of the androgenetic diphaploids. Differences between second cycle anther derived clones observed as well, indicated the induction of mutational events during microspore culture. Such variation of the regeneration parameters was also observed between protoplast cultures of an interdihaploid clone and of its protoclone. As in most experiments such variation is undesired, experiments were conducted to reduce the somaclonal variation. By optimizing the culture procedure, the undifferentiated callus phase could be reduced thus far, that the majority of the regenerants proved to be phenotypically uniform at the diploid or tetraploid ploidy level.