The origin of Asian pear cultivars inferred from DNA markers
For a long time, most of cultivated pears native to East Asia have been assigned to different species: Pyrus pyrifolia, P. bretschneideri and P. ussuriensis. A few cultivars commercially cultivated only in Xinjiang Province of China belong to P. sinkiangensis which has been proved to be a hybridization origin involving P. pyrifolia and P. communis. The majority of P. ussuriensis is cultivated in northeastern China and a minority in northeastern Japan. Its fruit with a small size needs ripening to become soft and edible. Cultivars of P. pyrifolia are mainly grown in South China and Japan, and are called Chinese sand pears in China and Japanese pears in Japan, respectively. Cultivars of P. bretschneideri (Chinese white pears) are cultivated in northern China. Chinese sand pears, Chinese white pears and Japanese pears are eaten at a crisp stage right after harvest or storage, and their origin is still controversial. Using RAPD, AFLP and SSR markers, we found that Chinese white pears were affinitive to Chinese sand pears and the majority of Japanese pears did not cluster together with Chinese sand pears which have been treated as the same germplasm with Japanese pears. A new nomenclature was proposed for the cultivar group of Chinese white pears: P. pyrifolia White Pear Group to replace the previously misused P. bretschneideri. Recently, we developed a new DNA marker in pears, retrotransposon-based sequence-specific amplification polymorphism (SSAP) marker. Based on this marker, we found that nearly all Asian pear species and cultivar groups experienced hybridization, and originated from five primitive genepools. Cultivated P. ussuriensis was proven to have originated from an interspecific hybridization between wild P. ussuriensis and cultivated P. pyrifolia, which had once been thought to be domesticated directly from wild P. ussuriensis. During the development of P. pyrifolia cultivars the gene introgression occurred from P. pashia to P. pyrifolia in southwestern China, while in northern China, the gene introgression happened from P. ussuriensis to P. pyrifolia. The knowledge of origins of cultivated Asian pears will be of help for pear cultivar improvement.
Teng, Y., Yu, P., Bai, S. and Jiang, S. (2021). The origin of Asian pear cultivars inferred from DNA markers. Acta Hortic. 1308, 1-6
Asian pear cultivar, Chinese sand pear, Chinese white pear, Japanese pear, Ussurian pear, Pyrus pyrifolia White Pear Group