Fingerprinting 146 Chinese chestnut (Castanea mollissima Blume) accessions and selecting a core collection using SSR markers

Chinese chestnut is an important nut tree around the world. Although the types of Chinese chestnut resources are abundant, resource utilization and protection of chestnut accessions are still very limited. Here, we fingerprinted and determined the genetic relationships and core collections of Chinese chestnuts using 18 fluorescently labeled SSR markers generated from 146 chestnut accessions. Our analyses showed that these markers from the tested accessions are highly polymorphic, with an average allele number (N-a) and polymorphic information content (PIC) of 8.100 and 0.622 per locus, respectively. Using these strongly distinguishing markers, we successfully constructed unique fingerprints for 146 chestnut accessions and selected seven of the SSR markers as core markers to rapidly distinguish different accessions. Our exploration of the genetic relationships among the five cultivar groups indicated that Chinese chestnut accessions are divided into three regional type groups: group I (North China (NC) and Northwest China (NWC) cultivar groups), group II (middle and lower reaches of the Yangtze River (MLY) cultivar group) and group III (Southeast China (SEC) and Southwest China (SWC) cultivar groups). Finally, we selected 45 core collection members which represent the most genetic diversity of Chinese chestnut accessions. This study provides valuable information for identifying chestnut accessions and understanding the phylogenetic relationships among cultivar groups, which can serve as the basis for efficient breeding in the future.