The haplotype-resolved genome assembly of the hexaploid kiwifruit Actinidia deliciosa reveals its hybrid origin and polysomic inheritance

The kiwifruit (genus Actinidia) exhibits extensive polyploidy, with natural populations ranging from diploid to tetraploid, hexaploid, and even higher ploidy levels. Actinidia deliciosa (green kiwifruit) is typically hexaploid (2n = 6x = 174), whereas its close relative A. chinensis (golden kiwifruit) is primarily diploid (2n = 2x = 58) or tetraploid. This ploidy diversity reflects a reticulate evolutionary history, likely shaped by hybridization and genome duplication involving multiple ancestral lineages. Determining the origin and inheritance of hexaploid A. deliciosa-the dominant kiwifruit species in global cultivation-is critical for understanding the role of polyploidization in the evolution of this species and for the development of breeding strategies.