香港牡蛎是我国华南地区贝类养殖的支柱产业，但近些年来，香港牡蛎产业面临着一些亟需解决的问题,例如繁殖期品质急剧下降、死亡率高、生长周期长等。三倍体育种能解决香港牡蛎产业中遇到的品质不稳定、生长慢、死亡率高等问题，研究及推广性腺不育或育性差、品质稳定、抗逆性强、生长速度快的香港牡蛎3N新品种成为养殖业者、消费者和研究者共同且迫切的要求。通过四倍体与二倍体杂交生产100%的三倍体，是规模化生产香港牡蛎3N的最优良且最根本的方法，获得稳定的四倍体群系是实现产业化全三倍体培育的重要保障。当3N♀×2N♂受精后抑制PB2是适合诱导香港牡蛎4N的一种新型优良方法，但是对于怎么进一步优化该方法？该方法诱导四倍体形成的机理及倍性稳定性如何？怎么建立稳定的香港牡蛎四倍体群系？香港牡蛎四倍体的生长及遗传特性如何？四倍体与二倍体杂交生产的3N、诱导3N和2N在生长及遗传方面有何差异？本课题正是基于这些问题和视角，拟通过荧光显微镜、共聚焦显微镜、荧光原位杂交、免疫荧光、转录组、代谢组等分子生物学和细胞生物学技术手段系统开展4N诱导新方法的优化，4N诱导形成新机制和倍性稳定性分析，4N稳定群系构建，4N、杂交3N、诱导3N和2N的生长比较和遗传特性解析等一系列研究深入解析香港牡蛎四倍体的形成机制及遗传特性。总的来说，本课题的研究不但对于探究香港牡蛎四倍体的诱导形成新机制及其遗传特性有重要科学意义，而且对于解决香港牡蛎二倍体产业遇到的问题和三倍体的规模化推广都具有十分重要的实际应用意义和价值。

Crassostrea hongkongensis (Hong Kong oyster) is a pillar industry of shellfish culture in Southern China, but in recent years, the Hong Kong oyster industry has faced some urgent problems, such as the rapid decline in quality during reproduction, high mortality and long growth cycle. Triploid breeding can solve the problems of unstable quality, slow growth and high mortality in the Hong Kong oyster (Crassostrea hongkongensis) industry. To study and promote the triploid Hong Kong oysters with low gonadal sterility or fertility, stable quality, strong resistance to stress and fast growth has become a common and urgent demand of farmers, consumers and researchers. The production of 100% triploid by crossbreeding tetraploid and diploid is the best and most fundamental method for large-scale production of the triploid Hong Kong oysters, and obtaining stable tetraploid population is an important guarantee for industrialized triploid cultivation. It is a new and excellent method to produce tetraploid by inhibiting polar body Ⅱ release after fertilization of triploid female and diploid male, but for how to further optimize the method? What is the mechanism and ploidy stability of tetraploid induced by this method? How to establish a stable Hong Kong oyster tetraploid population? What are the growth and genetic characteristics of tetraploid Hong Kong oysters? What are the differences in growth and heredity between hybrid triploids (hybridization between tetraploids and diploids), induced triploids and diploid Hong Kong oysters? Based on these problems and perspectives, a series of studies on the optimization of new tetraploid induction methods, analysis of new mechanism and ploidy stability of tetraploid induction, construction of tetraploid stable colony, growth comparison and analysis of genetic characteristics among tetraploid, hybridization triploid, induced triploid and diploid are carried out to analyze the formation mechanism and genetic characteristics of tetraploid Hong Kong oysters, by means of molecular and cell biology techniques such as fluorescence microscopy, confocal microscopy, fluorescence in situ hybridization, immunofluorescence, transcriptome, metabolic group, etc. In general, this research not only has great scientific significance for exploring the new mechanism and genetic characteristics of tetraploid induction in Hong Kong oyster, but also has very important practical application significance and value for solving the problems encountered in the diploid industry of Hong Kong oyster and the large-scale promotion of triploid Hong Kong oyster.