Genetic-cytoplasmic male sterility in progeny of 4x-2x crosses in cultivated potatoes.

Forty-three percent of the progeny from 4x × 2x crosses [Group Tuberosum cultivar x diploid hybrid (Groups Phureja or Stenotomum x Group Tuberosum haploid)] were male sterile. In contrast only four percent of the progeny from the reciprocal crosses were male sterile. Male sterility among the former progeny is presumed to result from the interaction of Tuberosum cytoplasm with dominant genes from the cultivated diploids, Groups Phureja and Stenotomum, an interaction known to occur in crosses of Tuberosum haploid x cultivated diploid species (2n = 2x = 24). The frequency of fertile progeny from the 4x × 2x crosses (57%) was significantly higher than that from the 2x × 2x crosses (Tuberosum haploid x cultivated diploid), (28%). The frequency of male fertility among progeny from different cultivars in 4x × 2x crosses varied from 31-82 percent. The difference between cultivars strongly suggests that some cultivars may have dominant male fertility restorer genes.