Genetic diversity and distribution pattern of economic seaweeds Pyropia yezoensis and Py. suborbiculata (Bangiales, Rhodophyta) in the northwest Pacific

Abstract

Pyropia yezoensis and Py. suborbiculata have been traditionally important for marine aquaculture as food resources in the northwest Pacific region. We conducted molecular analyses using plastid rbcL and mitochondrial COI-5P markers to identify their genetic diversity hotspot using samples collected from various locations of the northwest Pacific region as well as genetic information obtained from a public repository, representing specimens around the world. In the rbcL result, Py. yezoensis was separated into 19 haplotypes, and Py. suborbiculata was separated into 26 haplotypes. In COI-5P, 5 and 14 haplotypes were revealed in Py. yezoensis and Py. suborbiculata, respectively. We discovered a large number of haplotypes of Py. yezoensis in Hokkaido of Japan and high genetic diversity of Py. suborbiculata in the East Sea. Interestingly, Py. yezoensis and Py. suborbiculata showed unique haplotypes in the eastern coast of Korea. The distinction of haplotype composition between the East Sea and those of other regions in the northwest Pacific could be due to the divergence from environmental isolation of the East Sea during the Last Glacial Maximum. Our results show that the East Sea including Hokkaido of Japan is an important genetic diversity hotspot of Py. yezoensis and Py. suborbiculata and needs to be further monitored for conservation.