A de novo genome assembly of the dwarfing pear rootstock Zhongai 1.

'Zhongai 1' [(Pyrus ussuriensis × communis) × spp.] is an excellent pear dwarfing rootstock common in China. It is dwarf itself and has high dwarfing efficiency on most of main Pyrus cultivated species when used as inter-stock. Here we describe the draft genome sequences of 'Zhongai 1' which was assembled using PacBio long reads, Illumina short reads and Hi-C technology. We estimated the genome size is approximately 511.33 Mb by K-mer analysis and obtained a final genome of 510.59 Mb with a contig N50 size of 1.28 Mb. Next, 506.31 Mb (99.16%) of contigs were clustered into 17 chromosomes with a scaffold N50 size of 23.45 Mb. We further predicted 309.86 Mb (60.68%) of repetitive sequences and 43,120 protein-coding genes. The assembled genome will be a valuable resource and reference for future pear breeding, genetic improvement, and comparative genomics among related species. Moreover, it will help identify genes involved in dwarfism, early flowering, stress tolerance, and commercially desirable fruit characteristics.