Chromosome-scale genome assembly of a natural diploid kiwifruit (Actinidia chinensis var. deliciosa)

Abstract

The most commercialized kiwifruit, Actinidia chinensis var. deliciosa (Acd), is an allohexaploid (2n = 6x = 174), making high-quality assemblage genome challenging. We previously discovered a rare naturally occurring diploid Acd plant. Here, chromosome-level de novo genome assembly for this diploid Acd was reported, reaching approximately 621.98 Mb in length with contig and scaffold N50 values of 10.08 and 21.09 Mb, respectively, 99.66% of the bases anchored to 29 pseudochromosomes, and 38,990 protein-coding genes and 42.29% repetitive elements annotated. The divergence time of A. chinensis cv. ‘Red5’ and ‘Hongyang’ (11.1–27.7 mya) was more recent compared with the divergence time of them and Acd (19.9–41.2 mya), with the divergence time of A. eriantha cv. ‘White’ being the earliest (22.9–45.7 mya) among that of the four Actinidia species. The 4DTv distance distribution highlighted three recent whole-genome duplication events in Acd. This is the first high-quality diploid Acd genome, which lays an important foundation for not only kiwifruit functional genomics studies but also further elucidating genome evolution of allohexaploid Acd.