Genetic Structure And Genetic Diversity Of Mytilus Coruscus In The Coastal Waters Of Southeast China Sea

Mytilus coruscus Gould is one of the important shellfish resources in China, which iswidely distributed in southeast China ocean waters; it is large areas of breeding in Zhejiangand Fujian province. In recent years, due to overfishing, habitat damage, and pollution, thenatural stocks have been declining dramatically. This study mainly used methods ofinter-simple sequence repeat and16S rRNA to investigate the genetic structure and geneticvariation of four populations of M. coruscus in coastal waters of southeast China Sea,including the population of Zhoushan; the population of Wenzhou; the population ofNingde; the population of Fuzhou. Then Use various software tools to analyze andsummary of experimental results. The main results are as follows.1. Established and optimize the ISSR-PCR reaction system for M. coruscus. Throughthe exploration of the ISSR-PCR reaction system for M. coruscus, the effect of theconcentration of Mg2+, Taq DNA polymerase, dNTPs, and the concentration of the primerand the annealing temperature on the ISSR-PCR amplification were analyzed. The suitableISSR-PCR reaction system with a total volume of25l was as followed: Mg2+1.5mmol/L,Taq DNA polymerase1.0U, primer0.15mol/L, dNTPs2.0mmol/L, and the annealingtemperature is52℃.Using the optimized ISSR-PCR system and NO.847primer to obtainthe fingerprint of M. coruscus. The electrophoretogram had stronger polymorphism withhigher definition.2. The genetic structure of four geographic populations of M. coruscus along the coastof China was investigated by the inter-simple sequence repeat (ISSR) fingerprinting of120individual clams. In this study,13ISSR primers were screened, of the192ISSR loci tested,188(97.92%) were polymorphic. The genetic diversity was high at species level. The resultshowed that the PPL about four populations were among81.77%—89.58%, H were among0.2950—0.2818, I were among0.4213—0.4447, respectively for the four populations withthe lowest values in FZ population, the highest values in WZ population. The GSTof thefour populations was0.1519, Nm was3.0576—5.9714, AMOVA analysis showed that thegenetic variation mainly among individuals within populations. Genetic distance andUPGMA tree showed that WZ was clustered with ND into one clad, then with ZS, andfinally with FZ. The result showed that the further geographical distance, the higher geneticdistance; the genetic distance is proportional to the geographical distance.3. The sequence of16S rRNA was used to investigate the genetic structure and genetic variation of four populations of M. coruscus in coastal waters of southeast China Sea.Partial sequence of305bp was obtained through sequencing the16S rRNA gene of83individuals from four M. coruscus populations.150polymorphic sites,28haplotypes weredetected out of83individuals from four populations. The haplotype diversity index (Hd),mean nucleotide diversity index (Pi) and average number of nucleotide differences (K)reached0.810,0.09602and27.846, respectively. Results above showed that M. coruscus incoastal waters of southeast China Sea keep plentiful genetic variation in its naturalpopulations. The genetic structure test results show that the genetic distance among thepopulations of Zhoushan, Wenzhou, and Ningde were so low, their Fstamong－0.0141—0.0059, no significant divergence was detected (P>0.05). The genetic distancebetween the population of Fuzhou and other three populations were higher. Fstamong0.6217—0.6319, significant divergence was detected (P<0.01).4. In this study, by comparing and analyzing to the results of ISSR and16S rRNA, andthe analysis results of the genetic structure between populations are each other consistent,but it is a little difference in the genetic structure within populations. This was mainlybecause of the ability of detecting genetic variance of the two techniques; ISSR samplingvolume inadequate is one of main factors that affect the result.