Abstract:  Sargassum horneri is one of the important brown algae in coastal waters of Zhejiang Province with high ecological value. Analysis into the genetic diversity of Sargassum horneri populations can provide theoretical reference for resource protection， artificial breeding， and ecological restoration， etc. In this study， the genetic diversity of 80 individuals from 4 populations of Sargassum horneri was analyzed by amplified fragment length polymorphism （AFLP） method. Twenty primer pairs were selected from 64 primer pairs for the AFLP experiment. It was shown that 407 band loci were detected， of which 270 were polymorphic. The percentage of polymorphic loci （PPL） was 6634%. The percentage of polymorphic loci in each population varied from 3049% to 4654%， with an average of 3609%. Neis genetic diversity （H） was 0237 5， and Shannons information index （I） was 0374 1. The total genetic diversity for species （Ht） and the mean heterozygosity within populations （Hs） were 0314 2 and 0256 9， respectively. The total Gst was 0182 3， indicating that the major genetic variation was within populations， which accounted for 8177%， and the minor variation was among populations， which accounted for only 1823%. The gene flow within 4 populations was 1121 4， which reflected a certain amount of gene flow within the 4 populations in Zhejiang Province.

Key words: Sargassum horneri, AFLP, genetic diversity