The fecundity of triploid female Crassostrea gigas exhibited significant variation and was lower compared to diploid individuals. Previous studies categorized mature stage triploid female C. gigas into two groups: female α, characterized by a high number of oocytes, and female β, displaying few or no oocytes. To investigate the molecular mechanisms underlying irregular oogenesis and fecundity differences in triploid C. gigas, we performed a comparative analysis of gonad transcriptomes at different stages of gonadal development, including female α, female β, and diploids. During early oogenesis, functional enrichment analysis between female diploids and putative female β triploids revealed differently expressed genes (DEGs) in the ribosome and ribosome biogenesis pathways. Expression levels of DEGs in these pathways were significantly decreased in the putative female β triploid, suggesting a potential role of reduced ribosome levels in obstructing triploid oogenesis. Moreover, to identify regulatory pathways in gonad development, female oysters at the early and mature stages were compared. The DNA repair and recombination proteins pathways were enriched in female diploids and female α triploids but absent in female β triploids. Overall, we propose that decreased ribosome biogenesis in female triploids hinders the differentiation of germ stem cells, leading to the formation of a large number of abnormal germ cells and ultimately resulting in reduced fecundity. The variation in fertility among triploids appeared to be related to the degree of DNA damage repair during female gonad development. This study offers valuable insights into the oogenesis process in female triploid C. gigas.

三倍体雌性巨牡蛎的繁殖力表现出显着的变异，并且与二倍体个体相比较低。先前的研究将成熟阶段的三倍体雌性C. gigas分为两组：雌性 α 组，其特点是卵母细胞数量较多，雌性 β 组，其卵母细胞数量很少或没有。为了研究三倍体巨线虫卵子发生不规则和繁殖力差异的分子机制，我们对性腺发育不同阶段（包括雌性α、雌性β和二倍体）的性腺转录组进行了比较分析。在早期卵子发生过程中，雌性二倍体和假定的雌性β三倍体之间的功能富集分析揭示了核糖体和核糖体生物发生途径中不同表达的基因（DEG）。这些途径中 DEG 的表达水平在假定的雌性 β 三倍体中显着降低，表明核糖体水平降低在阻碍三倍体卵子发生中具有潜在作用。此外，为了确定性腺发育的调控途径，对早期和成熟阶段的雌性牡蛎进行了比较。DNA修复和重组蛋白途径在雌性二倍体和雌性α三倍体中丰富，但在雌性β三倍体中缺失。总的来说，我们认为雌性三倍体核糖体生物发生的减少阻碍了生殖干细胞的分化，导致大量异常生殖细胞的形成，最终导致繁殖力下降。三倍体生育力的差异似乎与女性性腺发育过程中 DNA 损伤修复的程度有关。这项研究为雌性三倍体C. gigas的卵子发生过程提供了宝贵的见解。