Genetic Diversity Of "Donghai No.1" F₆Families Of Pseudosciaena Crocea By Isozyme, RAPD And SSR

Large yellow croaker Pseudosciaena crocea, a commercially important marine fish, distributesmainly in nearshore and offshore areas of Zhejiang and Fujian Provinces, in southeastern China. This studywas to clarify the "DongHai NO.1" F6families genetic structures and to assess the genetic variationbetween F2and F6families by isozymes, RAPD and SSR. The results will provide academic foundations ingenetic potential and better management of breeding resource and hybridize breeding in future.Vertical polyacrylamide gel electrophoresis(PAGE) was used to detect the expression of15isozymes（LDH,ADH, MDH, ME, SOD, POD, EST, GAD, FDH, SCD, CAT, IDH, GDH,ACP, GcDH）in9tissues（eye, muscle, liver, kidney, spleen, heart, pectroral fin, gill and brain）on "DongHai NO.1" F6families of P.crocea family. The result was that：except CAT, IDH, GDH, ACP, GcDH,5isozymes showed weak andunsteady bands, the rest isozymes presented clear and steady bands in different tissues. The result ofhereditary difference showed26locis can be detected from the9isozymes and Est-1and Est-2waspolymorphic loci. The frequence of polymorphic, effective number of alleles, actual heterozygosity andexpected value is7.7%,0.8754,0.0631and0.0414respectively.The random amplified polymorphic DNA（RAPD）technique was applied to investigate the geneticvariation between the F2and F6families of P. crocea. All of the RAPD sites were generated from20indexsamples each in the F6families. Through the PCR amplification,13pairs random primers were chosenfor further amplification.87RAPD sites were detected in the F6families and each primers owned theRAPD sites varied from4to12, the mean number is6.69. There are20polymorphic loci in the87RAPDsites and the proportion of polymorphic loci can reached22.9%. The mean expected hetrozygosities andShannon’s diversity index of the F6families were0.2154and0.1043.The SSR was used to detect the genetic diversity from30index samples in F6families in this study.The results showed that the12pairs of primers all exhibited the polymorphism and detected44alleles, therange of variation is2~8and the mean value is2.631. Meanwhile, the range of expected heterozygosity andHobs variation is0.347~0.655and0.308~0.727, and the average expected heterozygosity(He) andHobs(Ho) is0.463and0.500, respectively. It revealed that the degree of genetic variation of F6families isin the intermediate level. The results of Hardy-Weinberg balance indicates one of the12pairs primersdeviate the balance(p<0.05). The12pairs primers all exhibited the polymorphism and the maximum PIC is0.610,8of12pairs primers showed high polymorphism (PIC>0.5) and hold66.7%. The results of SSRcan provide better theoretical basis for the further study of the genetic diversity of "DongHai NO.1"families.In additions, the compare were taken between "DongHai NO.1" F2and F6families which diversityresults were obtained by isozymes and RAPD. The results revealed that the F6families keeps the highlysimilarity with F2families in many genetic characteristics, just like the expression sites and number ofalleles of different isoenzymes were showed in F2and F6families. While, the difference still existed, just like the RAPD showed the F6families owned the lower polymorphism. It revealed that the genetic diversityof F6families decreased slightly along with the breeding. The reason of this phenomenon is owing to thecontrol of the effective breeding population.