Characterizing the link between cytoplasmic male sterility and PVY resistance in potato

Abstract

Cytoplasmic male sterility (CMS) in potatoes is a common reproductive issue in Potato Virus Y (PVY) breeding programs, as resistant sources typically have a wild cytoplasmic background (W, D, or T). In the San Luis Valley breeding program, the cytoplasmic types and PVY resistant clones' density are unknown. Similarly, the effects of these cytoplasmic types and resistance genes on reproductive traits have not been determined. This study aimed to characterize the cytoplasm types and investigate cytoplasm types and resistance genes' effects on pollen viability, pollen quantity, and seed set. The presence of T and W cytoplasm types was determined among the seven clones, with W type being more prevalent. This finding indicates that PVY resistant genes are concentrated between only these two cytoplasmic types. While the analysis revealed an impact of the cytoplasm types and genes on pollen viability, no significant differences were found in pollen quantity or seed set. All clones exhibited absent or low pollen viability and produced either absent or minimal amounts of pollen, suggesting low male fertility levels. The observed differences in pollen viability and seed set are thought to stem from difficulties in crossing and the influence of the female clones used. Notably, no berries were obtained from clones carrying the Rysto gene with W type cytoplasm, indicating their complete male sterility. The characterization of these cytoplasm types and the male sterility status will influence breeders in designing efficient mating combinations and will contribute to sustainable seed production, which requires a substantial quantity of seeds per cross.