珍珠贝的遗传育种研究

GENETICS—BREEDING STUDIES ON PEARL OYSTERS

本文对珍珠贝遗传和育种研究进展进行了综合评述，细胞遗传学研究结果表明，珍珠贝大多数种类染色体ｎ＝１４，无性染色体分化，核型的相似程度反映种间的亲缘关系。对珍珠贝的一些数量性状如形特征，壳色和生长速度等进行遗传分析，有助于确定数量性状的选育方法。合浦珠母贝贝壳棱柱层白色相对于褐色为隐性，现可培育出纯白色的群体。珍珠贝的生化遗传分析为选育和杂交育种提供了依据，并已用于亲子代鉴定。

Recent advances in Genetics and Breeding studies on pearl oysters were reviewed in this paper. The chromosome number of most pearl oysters which had been studied is N = 14, no sex chromosome was recongnised. Karyotype analysis had been performed on some species and banding technique is required for further study. Most commerically important traits of pearl oysters such as: Shell width, shell convekity, color of nacre and growth rate show quantative variation, some works had been done on estimating heritability of these traits,they provided useful parametes for conducting selective breeding. One of interesting discovery on qualitive trait inheritance is that the white coloration of shell (prismatic layer) of the Japanese pearl oyster is inherited under the control of a re- cessive gene. Electrophoretic analysis were conducted on some proteins and isozymes, it was used in parent——offspring identification and measuration of train purity, genetic identity and genetic distance between pearl oysters. Interspecific hybridization experiments resulted no true hybrid. While intraspe- cific hybridization between trains proved to be a valuable method in improving genetic structure of cul- tured stocks. Triploidy of pinctodn mnrtensii Dunker were induced with chemical and physical methods. Cytochalasin B treatment is the most efficient. But the percentage of tripliod decresed as the shell grew old. Gynogenetic diploid is also obtaind but the hatching rate is still poor. Further strdies should perform on (1) Protection of genetic resources (2) More detail inspectation of genetic structure of pearl oysters of our country. (3) Intraspecific hybridization and selective breed- ing . (4) the genome of pearl oysters. (5) somatic cell genetics study of pearl oysters, especially on ep- ithelium cells of mantle.