Japanese pear genome sequencing. Pyrus pyrifolia

Japanese pear is the second most produced fruit after apple in the family Rosaceae. There are more than 1,200 cultivated varieties of Japanese pears that have been bred for various traits. Although pedigree records of Japanese cultivated pears are partly traceable and phenotypic variation is well studied, their genetic relationship has not been elucidated. The genome sequence of Chinese pear, the ancestor of Japanese pears, enables us to analyze genotypic variation among Japanese pears. In the present work, we re-sequenced nine Japanese cultivated pears using next-generation sequencing technology, determined their genotypes, and clarified their evolutionary relationship. We also determined haplotype blocks by two statistical methods, runs test and multinomial test, to explain genome structures. The genotype and haplotype data are useful not only as DNA markers but also to explain different phenotypic trait among cultivars.