Genetic relationships of Chinese prickly ash as revealed by ISSR markers

Chinese prickly ash, belonging to the genus Zanthoxylum L., has been one of the most important commercially-exploited plants for its alimentary, industrial and medicinal applications. However, the breeding and promotion of Chinese prickly ash have been severely restricted due to its confusing classification. Therefore, we assessed genetic diversity and phylogenetic relationship among 45 Chinese prickly ash samples collected from 6 main cultivated regions using 11 ISSR primers. These eleven selected primers generated a total of 102 scorable bands ranging from 150 to 2000 bp, corresponding to an average of approximately 9.3 bands per primer. The percentage of polymorphic loci for all samples ranged from 75% to 100%, with an average of 84.3%. The genetic similarity coefficient across all samples varied from 0.460 to 0.919. Remarkably, UPGMA analysis showed that 45 samples were divided into six clusters with a genetic similarity of 0.7. The closest genetic relationship was observed between Dahongpao collected from Qin'an and Tianshui, and the greatest genetic divergence was found between Dahongpao collected from Hengshui and Jiuyeqing collected from Jiangjin. It could serve as a basis for identifying Chinese prickly ash cultivars, breeding new cultivars and protecting the Chinese prickly ash resources in main regions.