Genome assembly, resequencing and genome-wide association analyses provide novel insights into the origin, evolution and flower colour variations of flowering cherry.

Flowering cherry is a very popular species around the world. High-quality genome resources for different elite cultivars are needed, and the understanding of their origins and the regulation of key ornamental traits are limited for this tree. Here, a high-quality chromosome-scale genome of Prunus campanulata 'Plena' (PCP), which is a native and elite flowering cherry cultivar in China, was generated. The contig N50 of the genome was 18.31 Mb, and 99.98% of its contigs were anchored to eight chromosomes. Furthermore, a total of 306 accessions of flowering cherry germplasm and 6 lines of outgroups were collected. Resequencing of these 312 lines was performed, and 761267 high-quality genomic variants were obtained. The origins of flowering cherry were predicted, and these 306 accessions could be classified into three clades, A, B and C. According to phylogenetic analysis, we predicted two origins of flowering cherry. Flowering cherry in clade A originated in southern China, such as in the Himalayan Mountains, while clades B and C originated in northeastern China. Finally, a genome-wide association study (GWAS) of flower colour was performed for all 312 accessions of flowering cherry germplasm. A total of seven quantitative trait loci (QTLs) were identified. One gene encoding glycosylate transferase was predicted as the candidate gene for one QTL. Taken together, our results provide a valuable genomic resource and novel insights into the origin, evolution and flower colour variations of flowering cherry.