Analysis of Genetic Diversity and Construction of Fingerprint Profiles of Superior Trees of Cunninghamia lanceolata var．luotian

Objective This study aimed to clarify the genetic diversity characteristics of the superior tree population of Cunninghamia lanceolata var．luotian and to reveal the genetic relationships among these superior trees, so as to provide a basis for germplasm resource management, breeding parent selection, and the formulation of long-term breeding strategies.

Method A total of 17 SSR markers were used to genotype superior trees collected from three locations in Luotian County: Daqi Town (DQ), the Bodao Peak Forest Farm(BDF), and Xiaotashan Park(XTS). Genetic diversity parameters were estimated, and population genetic structure analysis, principal coordinate analysis and cluster analysis were conducted. In addition, fingerprint profiles of the superior trees were constructed.

Result Among the 17 SSR loci, 11 exhibited high polymorphism and effectively reflected the genetic diversity of the superior tree population. The average effective allele number (N_e), expected heterozygosity (H_e), and Shannon diversity index (I) were 2.084, 0.422, and 0.801, respectively, indicating a relatively high genetic diversity level. Among the three populations, the XTS population exhibited the highest genetic diversity, whereas the BDF population showed the lowest; however, the differences among populations were not significant. Genetic variation mainly occurred within populations, accounting for 95.29% of the total variation, while genetic differentiation among populations was extremely low. Population structure analysis showed that the superior trees did not form distinct genetic clusters. However, seven groups of identical genotypes were detected, involving 64 superior trees and accounting for 61.5% of the total population. After redundant genotypes were removed by retaining one representative from each identical genotype group, 47 unique superior trees remained. Using 11 primer pairs, all 47 retained superior trees were successfully distinguished, and unique fingerprint maps were established for each tree.

Conclusion The superior trees of C. lanceolata var. luotian exhibited relatively high genetic diversity, with genetic differentiation mainly distributed within populations and low differentiation among populations. Nevertheless, a large number of superior trees had highly similar or identical genetic backgrounds. At total of 57 superior trees with duplicated genotypes were screened and eliminated, and fingerprint profiles of the 47 retained superior trees are successfully constructed.