Title Progress of DNA Marker-Assisted Breeding in Maricultured Finfish
Authers Akiyuki OZAKI, Kazuo ARAKI, Hiroyuki OKAMOTO, Masanori OKAUCHI, Keiichi MUSHIAKE, Kazunori YOSHIDA, Tatsuo TSUZAKI, Kanako FUJI, Takashi SAKAMOTO, and Nobuaki OKAMOTO
Keywords marker-assisted selection (MAS), markers-assisted introgression (MAI), DNA marker, economic traits
Citation Bull. Fish. Res. Agen. No.35, 31-37, 2012
The marine products industry has developed based on direct catch from natural resources. However, because of the depletion and gradual restriction of aquatic resources, only recently has breeding been considered as an important research area. With the depletion of aquatic resources, the expectation regarding aquaculture research is increasing. Also genetic improvement of traits for improved culture is leading to superior varieties because we can improve the phenotype to suit aquaculture conditions by domestication of artificially produced fish with each generation.
 The essential conditions for DNA marker-assisted selection (MAS) is development of useful resource families to evaluate phenotypes and information about genetic linkages and a large number of polymorphic genetic markers. At the beginning of the study, we mainly aimed to use improved technologies on salmonid fish (Ozaki et al., 2001). But now the research and development are being applied to other kinds of maricultured fish. Some of the cases have already reached a practical stage and have been used in genetic improvement production. Two cases of MAS programs have succeeded in developing Japanese flounder resistant to lymphocystis disease (Fuji et al., 2007) and Atlantic salmon resistant to infectious pancreatic necrosis (Moen et al., 2009). These cases indicate the validity of the methodology.
 MAS breeding is applicable to other target species. However, there still remain problems and potential to further improve the methodology. One is markers-assisted introgression (MAI) or quantitative trait loci (QTL) pyramiding. MAI is the next phase of MAS. This method uses DNA markers of the responsible region for specific traits, and introgression hybridization to obtain several economic traits on one strain. We are carrying out research and development about MAI using Japanese flounder (Paralichthys olivaceus) as a target species. The other is effective utilization of natural genetic resources. At this point, aquatic resources have advantages because wild species have not beem selected and still maintain high genetic diversity. Individuals have high potential for genetic breeding regarding phenotypic characters. We are researching practical applications about selection of economic important traits from natural genetic resources using Japanese amberjack (Seriola quinqueradiata) as a target species.
URI http://www.fra.affrc.go.jp/bulletin/bull/bull35/35-5.pdf