Abstract: Pyropia haitanensis is one of the most important economic seaweeds for mariculture in China. In order to investigate genetic diversity of P. haitanensis, we collected 125 individuals from 11 populations along the southeast coast of China. We amplified 408 bp length of COX gene fragments and 488 bp length of rbcL gene fragments. The concatenated COX and rbcL gene fragments had a length of 896 bp, and the ratios of T, C, A, G were 34.9%, 14.6%, 34.2% and 16.3%, respectively. We detected 128 mutation sites, including 19 single-base mutation and 109 simple information sites. The mean nucleotide and haplotype diversity of 11 populations were 0.035 9±0.028 4 and 0.817 0±0.024 0, respectively. The concatenated COX and rbcL gene fragments defined 31 haplotypes from 125 individuals, and Hap1,Hap10 and Hap16 were the core haplotypes, accounting for 32.8%, 12.8% and 24.8% of all individuals, respectively. The result of distance analysis showed a linear correlation between population-pairwise genetic distances and geographic distances (R²=0.002 2, p=0.735 4). Genetic distance increased with the increased geographic distance, but geographic isolation had not yet been formed. The ML tree constructed from haplotypes showed no obvious geographical lineage structure in P. haitanensis, indicating potential gene exchange among populations.

Key words: Pyropia haitanensis, COX gene, rbcL gene, genetic diversity