Genetic diversity analysis and DNA fingerprinting of different populations of largemouth bass (Micropterus salmoides) in China with fluorescence-labeled microsatellite markers.

Background: Largemouth bass (Micropterus salmoides, LMB) is an economic fish in China, which has developed into many different cultured populations in the past decades. These populations exhibit different growth rates, morphological traits, stress resistance, and genetic diversity. Analyzing genetic diversity and molecular identification of these populations is crucial for conserving and utilizing germplasm resources, as well as for breeding new varieties.

Result: In this study, ten distinct LMB populations from China were collected and examined using fluorescence-labeled microsatellite markers. A total of 53 alleles were identified using seven microsatellite primer pairs, with allele counts ranging from 5 to 11 and an average of 7.571. The observed heterozygosity among the ten LMB populations varied from 0.210 to 0.967, while expected heterozygosity ranged from 0.204 to 0.651, and the polymorphism information content was between 0.175 and 0.597. Genetic distance varied from 0.019 to 0.457, the genetic differentiation index ranged from 0.013 to 0.258, and the number of effective migrants (Nm) was between 0.719 and 18.981. The genetic structure analysis indicated that the ten LMB populations could be classified into two or four groups. The analysis of molecular variance (AMOVA) revealed that 83.77% of genetic variation was found within individuals, with only 16.23% attributed to differences among populations. Through construction of DNA fingerprinting, we discovered unique fragments at several loci were detected in the populations such as the reintroduced Northern LMB population, "Youlu No.3" population, and the hybrid populations. Additionally, we also created digital DNA fingerprint maps of these LMB populations. Through analysis the digital DNA fingerprints from four candidate LMB populations, three known populations corresponded with the populations collected in this study. These results indicated high identification efficiencies of the digital DNA fingerprinting created in this study.

Conclusion: We established a method to distinguish 10 different LMB populations in China, which will assist in identification, traceability management, protection, and intellectual property rights of LMB in the future.