Genome-wide association studies and genomics-informed breeding for tuber dormancy in tetraploid potatoes

Upon harvest, potato (Solanum tuberosum L.) tubers enter a dormant state and do not sprout even under favorable conditions. Early dormancy break causes tuber spoilage and reduces postharvest quality. Common sprout control methods may compromise tuber quality, raise health and environmental concerns, and increase costs. Thus, potato varieties with long tuber dormancy are desirable to reduce tuber spoilage and lower costs for sprout prevention. This study aimed to (i) explore phenotypic variation in tuber dormancy length among advanced tetraploid potato genotypes and several public cultivars, (ii) understand the genetic basis of tuber dormancy, and (iii) obtain genomic-estimated breeding values (GEBVs) using genomic selection. A panel of 216 tetraploid potato genotypes, mostly from the Texas A&M Potato Breeding Program, was grown in Springlake and Dalhart, TX, from 2019 to 2021, for tuber dormancy evaluation. An additional panel of 82 genotypes was evaluated in 2022. A wide range of tuber dormancy lengths was observed, and significant variations were found among genotypes, field locations, storage conditions, and market groups. Quantitative trait loci were detected on chromosomes 1, 2, 3, 5, 6, 9, and 11, each explaining up to 11.8% of phenotypic variation. In addition, GEBVs were obtained using StageWise. Potato genotypes with high GEBVs for tuber dormancy length are potential donors of genes that can extend the dormancy period. Variation in tuber dormancy among advanced tetraploid potato genotypes highlighted the potential for selection. The genomic regions identified and the GEBVs provided valuable insights into the genetic basis of potato tuber dormancy, offering guidance for breeding.