Genomic Prediction for Inbred and Hybrid Polysomic Tetraploid Potato Offspring

Potato genetic improvement begins with crossing cultivars or breeding clones which often have complementary characteristics for producing heritable variation in segregating offspring, in which phenotypic selection is used thereafter across various vegetative generations (T i ). The aim of this research was to determine whether tetrasomic genomic best linear unbiased predictors (GBLUPs) may facilitate selecting for tuber yield across early T i within and across breeding sites in inbred (S 1 ) and hybrid (F 1 ) tetraploid potato offspring. This research used 858 breeding clones for a T 1 trial at Umeå (Norrland, 63°49′30″ N 20°15′50″ E) in 2021, as well as 829 and 671 clones from the breeding population for T 2 trials during 2022 at Umeå and Helgegården (Skåne, 56°01′46″ N 14°09′24″ E), respectively, along with their parents (S 0 ) and check cultivars. The S 1 and F 1 were derived from selfing and crossing four S 0 . The experimental layout was an augmented design of four-plant plots across testing sites, where breeding clones were non-replicated, and the parents and cultivars were placed in all blocks between the former. The genomic prediction abilities (r) for tuber weight per plant were 0.5944 and 0.6776 in T 2 at Helgegården and Umeå, respectively, when T 1 at Umeå was used as the training population. On average, r was larger in inbred than in hybrid offspring at both breeding sites. The r was also estimated using multi-environment data (involving at least one S 1 and one F 1 ) for T 2 performance at both breeding sites. The r was strongly influenced by the genotype in both S 1 and F 1 offspring irrespective of the breeding site.