Cytoplasmic and Nuclear Effects on Agronomic Traits in Diploid Interspecific Potato Hybrids

The cultivated potato (Solanum tuberosum L.) is a globally important crop with a narrow genetic pool, making it vulnerable to biotic and abiotic stresses. The present study analyzed the relative content of the nuclear, mitochondrial, and plastid genomes and their contributions to agronomic traits in 30 diploid interspecific potato hybrids with diverse cytoplasmic types and pedigrees. The nuclear genome size (2C-value) was estimated using flow cytometry, while the organelle DNA content and cytoplasm types were determined by quantitative polymerase chain reaction (qPCR) and multiplex PCR, respectively. The genome size of individual diploid genotypes remained stable across cultivation conditions, such as in vitro or greenhouse environments. Significant variation was observed in genome size, organelle content, and cytoplasmic types, which were associated with differences in pollen fertility and starch content. Kendall's correlation analysis revealed a strong positive correlation between the content of plastid and mitochondrial DNA, and between starch content and chip colour after cold storage. Principal component analysis (PCA) demonstrated that variation in plastid and mitochondrial DNA content explained differences among genotypes, with nuclear DNA content contributing independently. Notably, cytoplasmic male sterility was observed in some T-type cytoplasm genotypes, thus highlighting the role of nuclear-cytoplasmic interactions. The results obtained demonstrate that organelle genome composition exerts a significant influence on agronomic traits and offer valuable insights into the potential for the enhancement of potato breeding programmes through the analysis of cytoplasm and nuclear genomes.