| The genetic diversity and relationships of six representative cultivars and six geographically isolated wild populations of Saccharina japonica (J.E. Areschoug) C.E. Lane, C. Mayes, Druehl & G.W. Saunders along northwest coasts of the Pacific were investigated using amplified fragment length polymorphism (AFLP) markers. A total of 547 bands were generated across all samples by ten primer combinations. At the population or cultivar level, the percentage of polymorphic loci (P), gene diversity (H) and Shannon's information index (I) was highest in the Dalian population (P: 59.05%; H: 0.2057; I: 0.3062) and lowest in the Lianjiang cultivar (P: 9.87%; H: 0.0331; I: 0.0497). At the species level, P, H and I was 85.01%, 0.1948 and 0.3096, respectively. Two UPGMA dendrograms were constructed respectively based on the Dice similarity coefficients among individuals and genetic distances among populations and cultivars. Analysis of molecular variance (AMOVA) revealed that a higher portion (60.21%) of variations resided among cultivars and populations, while a lower portion (39.79%) within cultivars and populations. The GST value was 0.6226, consistent with FST (0.6021), and the gene flow (Nm) was 0.1515, indicating strong genetic differentiation among cultivars and populations. The Mantel test suggested that genetic distance or genetic differentiation was positively correlated with geographic distance (r=0.8870, P=0.007 and r=0.7962, P=0.011, respectively) in the six wild populations, agreeing with the IBD (isolation by distance) model. On the whole, low to moderate genetic diversity within cultivars or populations (except Dalian population) and high genetic differentiation among cultivars and populations were detected.AFLP and microsatellite markers were adopted to assess the genetic identity of the sporophytic offspring derived from mono-crossing of gametophyte clones of Undaria pinnatifida. In this investigation, two mono-crossing lines (M1 and M2) and two selfbreeding lines (S1 and S2) were constructed, and a wild population (W) was collected. A total of 318 loci were detected using eleven AFLP primer combinations. The percentage of polymorphic loci in M1, M2, S1, S2 and W was 4.7%, 0.3%, 17.9%, 16.4% and 36.5%, respectively. The genetic identity in M1 and M2 (95.6-100%) was higher than that in S1, S2 (87.7-98.4%) and W (81.5-92.1%). In microsatellite analysis, six loci were used. For either M1 or M2, almost identical genotype was detected at every locus except for M1 at locus Up-AC-2B2, which differentiated M1 into two kinds of genotypes. For S1, S2 or W, different genotypes were detected at two or more loci. In conclusion, high genetic identities were found in sporophytic offspring derived from mono-crossing of gametophyte clones of U. pinnatifida by means of both AFLP and microsatellite markers, however, subtle genetic variations were also detected.Twelve strains and a representative farmed population of Hizikia fusiformis were sampled from its principal cultivation ground, i.e. Dongtou county, Zhejiang province. Important characteristics of these strains were compared and genetic diversity of the population was analyzed using AFLP technique. Morphological analysis revealed significant differences among these 12 strains in terms of total length, total wet weight, branchlet length, branchlet wet weight and brachlet density(P<0.05 or P<0.01). In AFLP analysis, a total of 198 fragments were amplified in twenty-seven individuals of the representative population by means of eight primer combinations, of which 166 were polymorphic. The percentage of the polymorphic fragments was 83.3%. A UPGMA dendrogram was constructed based on the genetic distances among the individuals, in which twenty-seven individuals of H. fusiformis clustered into one clade and the control individual of Sargassum horneri clustered into another one. In conclusion, high genetic diversity was revealed in the farmed population of Hizikia fusiformis from both morphological and molecular level. |
PDF Full Text Request