Reaction to phytotoxins in a potato population derived from mesophyll protoplasts

General resistance to late blight of Solanum tuberosum plants regenerated from callus resistant to culture filtrates of Phytophthora infestans

Resistance of potato leaflets to culture filtrates of Phytophthora infestans is correlated with lower growth of the congenial parasite but not with lower sporulation.

Selection of potato callus for resistance to culture filtrates of Phytophthora infestans and regeneration of resistant plants

Dihaploid calli from Solanum tuberosum were selected, which were resistant to the culture filtrate of Phytophthora infestans. Each of the resistant calli was resistant to all four pathotypes of Phytophthora used in these experiments. The resistance was not lost through regeneration and the induction of new callus.

Comparison of single cell culture derived Solanum tuberosum L. plants and a model for their application in breeding programs

The techniques of microspore and protoplast regeneration starting from dihaploid Solanum tuberosum plants has been improved to such an extent that the production of more than 2000 microspore derived A1 plant lines and of several hundred protoplast derived plantlets has become possible. Further, from the dihaploid Solanum species S. phureja the regeneration of microspores to plants, and from the species S. infundibuliforme, S. sparsipilum and S. tarijense the regeneration of protoplasts to calluses, has been achieved. The plants descending from the two single cell culture systems are compared with reference to phenotypic markers and economic qualities. Some principles characteristic for either microspore or protoplast derived plants are examined and their significance is discussed. The results are compiled into an extended analytical synthetic breeding scheme based on a stepwise reduction of the autotetraploid to the monohaploid level and a subsequent controlled combination to a new synthetic completely heterozygous tetraploid potato.