The wild relatives of cultivated Saccharina japonica belong to the genus Saccharina, with S. cichorioides serving as a vital source of wild germplasm for kelp breeding due to its superior tolerance and higher polysaccharide content. However, limited understanding of its population structure and genetic diversity often leads to increased operating costs and longer breeding process times.
Recently, the research team led by Prof. DUAN Delin from the Institute of Oceanology of the Chinese Academy of Sciences (IOCAS), along with collaborators from Japan and Russia, revealed the genetic background of the important wild crop relatives.
The study was published in Aquaculture on Jun. 6.
Combined with five other species in the Saccharina genus, 13 populations of S. cichorioides were used to estimate genetic diversity, population structure, and evolutionary history based on the mitochondrial marker COI and 9 microsatellite markers.
The researchers revealed that S. cichorioides can be subdivided into two distinct groups. These groups exhibit significant genetic differentiation and limited gene flow. Populations along the coast of the Sea of Japan (the JPS group) display high levels of genetic diversity, while populations along the east coast of Sakhalin Island (the OKS group) represent ancient populations.
Among the six studied species, S. cichorioides exhibits the highest haplotype and nucleotide diversity. Significant genetic differentiation is evident among these wild crop relatives.
Gene flow analysis revealed no gene introgression between the JPS and OKS groups. The researchers inferred that the Soya Strait may act as a barrier limiting genetic exchange between populations of S. cichorioides.
In this study, the high levels of genetic diversity were mainly found in populations located along the shoreline of the Sea of Japan. "Therefore, combined the high genetic diversity and strong tolerance, these populations may be valuable resources for the breeding purpose of kelp aquaculture," said ZHANG Jie, the corresponding author of the study.
Relationship and geographical distribution of S. cichorioides and its closely related species. (Image by IOCAS)
Yu Ma, Jie Zhang, Haojie Qiao, Yuqun Du, Norishige Yotsukura, Anna V. Klimova, Nina G. Klochkova, Tatiana N. Krupnova, Dmitry A. Galanin, Delin Duan. (2025). Distinct genetic groups with restricted gene flow in wild crop relatives Saccharina cichorioides from the northwestern Pacific. Aquaculture. 609.742804.
(Text by ZHANG Jie)
Media Contact:
ZHANG Yiyi
Institute of Oceanology
E-mail: zhangyiyi@qdio.ac.cn
(Editor: ZHANG Yiyi)