A chromosome-scale strawberry genome assembly of a Japanese variety, Reikou

Cultivated strawberry (Fragaria × ananassa) is an octoploid species (2n = 8x= 56) that is widely consumed around the world as both fresh and processed fruit. In this study, we report a chromosome-scale strawberry genome assembly of a Japanese variety, Reikou. The Illumina short reads derived from paired-end, mate-pair, and 10X Genomics libraries were assembled using Denovo MAGIC 3.0. The generated phased scaffolds consisted of 32,715 sequences with a total length of 1.4 Gb and an N50 length of 3.9 Mb. A total of 63 pseudomolecules including chr0 were created by aligning the scaffolds onto the Reikou S1 linkage maps with the IStraw90 Axiom SNP array and ddRAD-Seq. Meanwhile, genomes of diploid Fragaria species were resequenced and compared with the most similar chromosome-scale scaffolds to investigate the possible progenitor of each subgenome. Clustering analysis suggested that the most likely progenitors were F. vesca and F. iinumae. The phased pseudomolecules were assigned the scaffolds names with Av, Bi, and X, representing sequence similarity with F. vesca (Av), F. iinumae (Bi), and others (X), respectively. The result of a comparison with the Camerosa genome suggested the possibility of subgenome structure differences between the two varieties.