Identification, Elucidation and Deployment of a Cytoplasmic Male Sterility System for Hybrid Potato.

Recent advances in diploid F 1 hybrid potato breeding rely on the production of inbred lines using the S-locus inhibitor ( Sli ) gene. As a result of this method, female parent lines are self-fertile and require emasculation before hybrid seed production. The resulting F 1 hybrids are self-fertile as well and produce many undesirable berries in the field. Utilization of cytoplasmic male sterility would eliminate the need for emasculation, resulting in more efficient hybrid seed production and male sterile F 1 hybrids. We observed plants that completely lacked anthers in an F 2 population derived from an interspecific cross between diploid S. tuberosum and S. microdontum . We studied the antherless trait to determine its suitability for use in hybrid potato breeding. We mapped the causal locus to the short arm of Chromosome 6, developed KASP markers for the antherless ( al ) locus and introduced it into lines with T and A cytoplasm. We found that antherless type male sterility is not expressed in T and A cytoplasm, proving that it is a form of CMS. We hybridized male sterile al/al plants with P cytoplasm with pollen from al/al plants with T and A cytoplasm and we show that the resulting hybrids set significantly fewer berries in the field. Here, we show that the antherless CMS system can be readily deployed in diploid F 1 hybrid potato breeding to improve hybridization efficiency and reduce berry set in the field.