Assessing the Genetic Diversity and Genealogical Reconstruction of Cypress (Cupressus funebris Endl.) Breeding Parents Using SSR Markers

To identify genetic diversity, genetic structure and the relationship among accessions, and further establish a core collection for the long-term breeding of cypress (Cupressus funebris Endl.), the genealogy of breeding parents was reconstructed using simple sequence repeat (SSR) molecular markers. Seventeen SSR markers were used to detect molecular polymorphisms among 290 cypress accessions from five provinces and 53 accessions with unknown origin in China. A total of 92 alleles (Na) were detected with 5.412 alleles per locus and an average polymorphism information content (PIC) of 0.593. The haplotype diversity (H) ranged from 0.021 to 0.832, with an average of 0.406. The number of alleles (Na) and the effective number of alleles (Ne) ranged from 4.294 to 5.176 and from 2.488 to 2.817 among five populations, respectively. The pairwise population matrix of Nei's genetic distance ranged from 0.008 to 0.023. Based on the results of unweighted pair group method average (UPGMA) cluster and population structure analyses, 343 breeding parents were divided into two major groups. Lower genetic differentiation coefficients and closer genetic relationships were observed among cypress breeding parents, suggesting that the genetic basis was narrow, and the genetic relationship was confused by frequent introduction and wide cultivation. Moreover, we reconstructed the genealogy between breeding parents and 30 accessions of breeding parents from an identified core collection. According to the present study, not only geographic origin but also the relationship of the individuals should be considered in future crossbreeding work.