Genetic diversity of Malus cultivars and wild relatives in the Chinese National Repository of Apple Germplasm Resources

Authors: GAO, YUAN - Chinese Academy Of Agricultural Sciences; LIU, FENGZHI - Chinese Academy Of Agricultural Sciences; WANG, KUN - Chinese Academy Of Agricultural Sciences; WANG, DAJIANG - Chinese Academy Of Agricultural Sciences; GONG, XIN - Chinese Academy Of Agricultural Sciences; LIU, LIJUN - Chinese Academy Of Agricultural Sciences; Richards, Christopher; Henk, Adam; Volk, Gayle

Submitted to: Tree Genetics and Genomes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2015
Publication Date: 9/24/2015
Publication URL: https://handle.nal.usda.gov/10113/62431
Citation: Gao, Y., Liu, F., Wang, K., Wang, D., Gong, X., Liu, L., Richards, C.M., Henk, A.D., Volk, G.M. 2015. Genetic diversity of Malus cultivars and wild relatives in the Chinese National Repository of Apple Germplasm Resources. Tree Genetics and Genomes. 11:106. doi:10.1007/s11295-015-0913-7.

Interpretive Summary: This publication is the result of a collaboration between scientists at the USDA-ARS and at the Chinese Academy of Agricultural Sciences (CAAS). The genetic diversity and differentiation of apple cultivars and several closely related wild relative species maintained at the CAAS Research Institute of Pomology in Xingcheng, China was assessed with 16 nuclear SSR markers,. The diversity of apple cultivars derived from Chinese and Western (mostly from North American and Western European sources) was similar. Of the cultivated apple types, the cultivars from Former Soviet Republics were most similar to M. sieversii, a progenitor species of apple. The apple cultivars from the Former Soviet Republics may be sources of novel forms of desirable traits for use in breeding programs, since they may represent an independent lineage distinct from Western apple cultivars.

Technical Abstract: The Research Institute of Pomology (IP), Chinese Academy of Agricultural Sciences (CAAS) in Xingcheng, China, maintains hundreds of apple accessions that originated from around the world. We have used 16 microsatellites to assess the diversity and differentiation of 391 accessions within the IP that represent M. × domestica (from China, Japan, Former Soviet Republics, and Western countries) as well as the crop wild relative species M. baccata, M. prunifolia, M. x robusta, and M. sieversii. We identify genetic relationships among these eight source categories that suggest that of the M. × domestica cultivars, those from the Former Soviet Republics are the most closely related to M. sieversii and may represent an independent lineage of domesticated apples distinct from those found in Western Europe or North America. We show that the M. × domestica cultivars from China and Western sources are genetically similar, whereas the cultivars from Japan are distinct. We also describe two accessions of M. × domestica ssp. chinensis landraces that are believed to be over 2000 years old that are more similar to wild species than most of the M. × domestica cultivars. We show that the wild, landrace, and cultivar accessions within the IP offer novel diversity to apple breeding programs.