Breeding studies on red sea bream Pagrus major: mass selection to genome editing

Red sea bream Pagrus major is extremely important in the aquaculture of Japan. The breeding of red sea bream, which has a history of more than half a century, can be divided into three main categories. The first is selective breeding. The Aquaculture Research Institute, Kindai University, began breeding fast-growing red sea breams in the early 1960s through mass selection. I summarized the results of the selection and characteristics of the fish in the 1990s. The second is breeding through chromosome manipulation and sex control. Two types of gynogenetic diploids (G2N) were artificially induced. Although growth and survival of G2N were inferior, the growth of heterozygous clones produced by mating G2N was comparable to normal diploids. The sex differentiation process and the induction condition of all-male groups by 17α-methyltestosterone treatment were clarified, and the percentage of females could be increased to more than 85%. The third is breeding through genetic manipulation. We first developed the microinjection method, and succeeded in increasing the percentage of edible ratio by deleting the function of myostatin gene by genome editing. Combining new technologies, such as genome editing, with the existing breeding methods mentioned above would result in faster and more effective breeding.