Abstract:Cytogenetic analysis is a valuable tool for germplasm study and protection. In order to clarify the Germplasm resources of Epinephelus moara, the metaphase chromosomes of E. moara of Tokyo Bay population were obtained from the head kidney tissue by the method of PHA and colchicine injection and the karyotype was analyzed by using microscopes. We observed 464 mitotic metaphases from 6 individuals, and 356 of all observed mitotic metaphases (76.72%) showed 2n = 48 chromosomes, which indicated that there were 48 chromosomes in the diploid. We then analyzed 10 mitotic metaphases and calculated the relative length and arm ratio of the chromosomes. The relative length of the chromosomes in E. moara of Tokyo Bay population varied from (5.13±0.15) % to (2.81±0.13) %. The arm ratio of the 14th chromosome was 2.35±0.14, and the arm ratio of the 16th chromosome was 2.71±0.24. The 24th chromosome had the minimum arm ratio, which was 1.99±0.13. According to arm ratio, the diploid consisted of 6 submetacentric, and 42 telocentric chromosomes, and the fundamental number of chromosome arms was 54, which indicated karyotypic formula in E. moara of Tokyo Bay population was 2n = 48，6sm + 42t，NF = 54. The form of the 24th chromosome was changed in different metaphase from the same individual (the shorter arm changed among filiform, T type, and SM type), which may be related with the expressed activity of the rDNA in nucleolar organizing region. By comparison with the chromosome karyotypes of other Epinephelus species, E. moara has the evolutive characteristics of karyotypic pattern and belongs to the specialization group. As detected, the karyotypes of E. moara were different between Japan (Tokyo Bay) and China (Xiamen coastal waters) samples, which may be caused by geographic isolation. There were abundant genetic diversity among different geographic populations, and the germplasm improvement of E. moara could be accelerated by heterosis among different geographic groups.
