ISSR Analysis On Genetic Diversity Of Six Sargassum Thunbergii Populations

Sargassum thunbergii is a common seaweed which has high economic and nutritional values. It is a kind of warm-temperate seaweed.With the rapid development of sea cucumber aquaculture industry, the demand of S. thunbergii is rising rapidly. In order to know it deeply,the genetic diversity of six geographic populations of Sargassum thunbergii along the coast of Dalian and Penglai are investigated by the inter-simple sequence repeat (ISSR).The six geographic populations are SHICHENGDAO(SC), JIANGJUNSHI(JJ), DACHANGSHAN(DC), DONGTUOZI(DT), YANCHANG(YC) and PENGLAI(PL).Of the 160 ISSR loci tested, 145 (90.62%) are polymorphic with 14 different ISSR primers. The results show that the values of percentage of polymorphic bands (PPB), Shannon's information index (I) and Nei's gene diversity (H) are 41.25%~64.38%, 0.2321~0.3464 and 0.1585~0.2333 respectively.The result indicate that the genetic diversity within the six populations is high, while the genetic diversity within the five Dalian populations is higher than in Shandong's. Analysis of molecular variance (AMOVA) reveal that a higher portion (64.34%) of variations are detected within populations, while a lower portion (35.66%) of variation is found among populations, the Fst is 0.3566 among the different populations so that the most variations are in the populations.The UPGMA tree based on the Nei'genetic identity shows that DC is clustered with DT, then with JJ, SC and YC, and finally with PL. The information will be valuable for the cultivation and conservation for Sargassum thunbergii.The results show that genetic diversity is high within the six populations. The most variations are in the populations. That relationship of populations is decided on the geographical distance and the external environmental factors such as high salt and so on.