Vitellogenin (Vg) is important for insect egg maturation and embryo development. In the present study, we characterized the molecular structure and expression profile of Vg gene, and analyzed its reproductive functions in diamondback moth, Plutella xylostella (L.), a destructive pest of cruciferous crops, using CRISPR/Cas9 system. The P. xylostella Vg (PxVg) included all conserved domains and motifs that were commonly found in most insect Vgs except for the polyserine tract. PxVg gene was highly expressed in female pupae and adults. PxVg protein was detected in eggs and female adults. PxVg was mainly expressed in the fat body and its protein was detected in most tissues, except in the midgut. CRISPR/Cas9-induced PxVg knockout successfully constructed a homozygous mutant strain with a 5-base pair nucleotide deletion. No PxVg protein was found in the mutant individuals and in their ovaries. There were no significant differences between wild (WT) and mutant (Mut-5) types of P. xylostella in terms of ovariole length and the number of fully developed oocytes in newly emerged females. No significant difference was observed in the number of eggs laid within two days, but there was a lower egg hatchability (84% for WT vs. 47% for Mut-5). This is the first study presenting the functions of Vg in ovary development, egg maturation, oviposition and embryonic development of P. xylostella. Our results suggest that the reproductive functions of Vg may be species-specific in insects. It is possible that Vg may not be the major egg yolk protein precursor in P. xylostella. Other “functional Vgs” closely involved in the yolk formation and oogenesis would need to be further explored in P. xylostella.

卵黄蛋白原（Vg）对于昆虫卵的成熟和胚胎发育很重要。在本研究中，我们表征了Vg基因的分子结构和表达谱，并使用CRISPR / Cas9系统分析了其在小菜蛾小菜蛾Plutella xylostella（L.）中的繁殖功能。该小菜蛾VG（Px的VG）是包含了常用的大多数昆虫的Vgs发现除丝氨酸道所有保守结构域和图案。PxVg基因在雌性up和成虫中高表达。在鸡蛋和成年女性中检测到Px Vg蛋白。病毒蛋白质主要在脂肪体内表达，除中肠外，在大多数组织中均检测到蛋白质。CRISPR / Cas9诱导的PxVg敲除成功构建了具有5个碱基对核苷酸缺失的纯合突变株。无Px的Vg的蛋白在突变的个体，并在其卵巢中发现。野生型（WT）和突变型（Mut-5）的小菜蛾之间在卵巢长度和新生雌性卵母细胞数量方面没有显着差异。两天内产卵的数量没有显着差异，但是孵化率较低（野生型为84％，而Mut-5为47％）。这是第一个介绍Vg功能的研究在卵巢发育，卵子成熟，产卵和胚胎发育小菜蛾。我们的结果表明，Vg的生殖功能在昆虫中可能是物种特异性的。Vg可能不是小菜蛾的主要蛋黄蛋白前体。与小卵黄体形成和卵子发生密切相关的其他“功能性Vgs”将需要在小菜蛾中进一步探索。