家蚕新红卵突变体胚胎致死基因lre的鉴定及致死分子机理

The silkworm, Bombyx mori, is a vital economic insect and a model lepidopteran, and has been one of the animals best suited for physiological, developmental, and genetics studies. The new red egg mutant Fuyinhong was found in the process of germplasm resource preservation of silkworm (Bombyx mori) Fuyin. The new mutant is different from the previous red egg mutants of silkworm. Apart from the red color shown in the eggs, the mutant Fuyinhong can result in embryonic lethality. After incubated for 4-5 days, the homozygous recessive embryos would cease developing. Genetic analysis indicates that lethality is controlled by a recessive gene, which is lethal in the homozygous state and conforms to the general inheritance rules. In this study, based on the genetic analysis of Fuyinhong mutant, whole-genome resequencing method was used to search for differential genes between Fuyin and Fuyinhong. And then, the candidate genes of lre will be screened by analysing the RNA and protein expression characteristics of the differential genes, and the function of the candidate genes will be verified by reverse mutation.The study will lay a foundation for further study on the formation mechanism of the lre mutant. The results of the study can provide a theory basis for further study on the embryonic development of silkworm. Given that the lre mutant is a lethal egg mutant, it can provide genetic material for the development of genetic control technology of lepidopteran pests.

家蚕是一种重要的经济昆虫和鳞翅目模式昆虫，是研究动物生理、发育、遗传等生命现象的重要材料。"芙印红"是云南近年在家蚕种质资源保存中发现的一种新的红卵突变体，不仅卵色表现为红色，且具有胚胎期致死性，在催青后4-5天胚胎即停止发育。遗传分析发现其致死性由一个隐性遗传基因控制，纯合致死，遵循普通的遗传学规律。本研究针对这一致死性状，在经典遗传分析的基础上，通过基因组重测序比较正常个体与突变个体基因组之间的序列差异，寻找差异基因，并从RNA水平和蛋白水平研究分析差异基因的表达特征，获得胚胎致死基因lre的候选基因，并通过回复突变技术验证候选基因的功能，初步明确新红卵突变体胚胎致死的分子机制。本研究将从分子水平上解析家蚕新红卵突变体胚胎致死机理这一关键科学问题，研究结果对于阐明家蚕胚胎发育的原理具有重要意义，也可为该基因作为鳞翅目农林害虫种群遗传控制技术的靶标基因素材提供理论依据。

家蚕是完全变态发育的鳞翅目昆虫，分为卵、幼虫、蛹和成虫四个发育阶段。卵期是家蚕发育的一个重要时期，卵的好坏直接影响到幼虫、蛹和成虫的发育。本项目以具有胚胎期致死性的家蚕卵突变体Fuyin-lre（芙印红）为材料，通过对Fuyin-lre胚胎的表型观测，确定了Fuyin-lre胚胎在发育早期（丙1期）即停止发育；遗传规律分析表明Fuyin-lre的胚胎致死性由一个与红卵基因re紧密连锁的隐性遗传基因控制，纯合致死，遵循孟德尔遗传规律；DGE及基因组序列分析显示，Fuyin-lre的发生是由于突变区域发生了基因组大片段的缺失和插入，含红卵基因re在内的9个紧密连锁的基因（约280kb）发生集体缺失所致，而大片段的缺失可能与具有转移大片段能力的家蚕转座子Bmmar1有关；对突变区域内9个基因的表达及序列分析显示，红卵基因re与基因BGIBMGA003696-TA不具有胚胎致死性；对剩余7个基因进行RNAi显示，7个基因中的5个基因在RNAi后胚胎仍能够正常发育，而基因BGIBMGA003697-TA和BGIBMGA003700-TA在RNAi后胚胎发育困难，仅有极少数胚胎能够发育到后期，表明基因BGIBMGA003697-TA和BGIBMGA003700-TA对家蚕胚胎发育具有重要影响。家蚕是鳞翅目模式昆虫，胚胎致死效应在鳞翅目害虫防治中具有潜在应用价值，研究结果对于阐明家蚕胚胎发育的原理具有重要意义，也可为该基因作为鳞翅目农林害虫种群遗传控制技术的靶标基因素材提供理论依据。