家蚕非滞育红卵突变体Re-nd的遗传分析

Genetic analysis of the non-diapause red egg mutant Re-nd in the silkworm,Bombyx mori

【目的】家蚕Bombyx mori非滞育红卵突变体Re-nd是家蚕品种C108经化学诱变剂N-甲基-N-亚硝基脲(N-methyl-N-nitrosourea,MNU)诱导产生的新型卵色突变体,属于浆液膜突变。本研究旨在通过传统的遗传学方法分析其突变表型产生的机理,为进一步对Re-nd突变基因的克隆和功能研究及应用奠定基础。【方法】非滞育家蚕突变体Re-nd与野生型滞育的二化品种大造(Dazao)和非滞育的多化品种N4杂交、同胞交配及回交,然后进行遗传分析;同时,Re-nd与已知滞育白卵突变体w-2、桃红眼白卵突变体pe及红卵突变体re杂交、同胞交配及回交,然后进行遗传分析。【结果】结果显示,Re-nd分别与大造和N4杂交F 1代的非滞育卵都为淡红色;同胞交配的F 2代非滞育卵色为红色、淡红色和淡黄色,其红卵(包括淡红色卵)与淡黄色卵的数量比基本符合3∶1;回交B 1代非滞育卵为红色和淡黄色,其数量比基本符合1∶1。Re-nd与w-2和pe杂交的F 1代均表现为淡褐色滞育卵色;与w-2杂交产生的F 2代滞育卵色表型有正常深褐色、淡褐色、黄色以及淡黄偏微红色,非滞育卵表型有红色、淡黄偏微红色、橙黄色以及淡黄色;与pe杂交产生的F 2代卵都是滞育卵,其卵色表型有正常深褐色、淡褐色、淡黄偏微红色以及红色;与re杂交F 1代均表现为淡褐色滞育卵色,F 2代都为滞育卵,其卵色表型有正常深褐色、淡褐色以及红色,re亲本滞育卵的颜色为红色,F 2代卵中并没有分离出新的卵色。【结论】通过杂交和遗传分析,证实了Re-nd突变体为独立的显性遗传,Re-nd突变基因位于w-2及pe突变基因的下游,可能参与了不同于野生型卵色素代谢分支,即卵中眼色素生物合成后期3-羟基-犬尿氨酸进一步代谢合成奥敏类(ommatins)色素的过程。

【Aim】Re-nd,a non-diapause red egg mutant of the silkworm,Bombyx mori,is a new egg color mutant.It was obtained by mutagenesis of the C108 strain induced by the chemical mutagen N-methyl-N-nitrosourea(MNU),belonging to serous membrane mutation.This study aims to analyze the mechanism of mutant phenotype by traditional genetic methods,so as to lay a foundation for further cloning,functional research and application of the mutant genes of Re-nd.【Methods】The hybridizing,sib mating and backcrossing between non-diapause mutant Re-nd and the wild-type diapause bivoltine Dazao strain and non-diapause polyvoltine N4 strain of B.mori,respectively,and the genetic analysis were carried out.Meanwhile,the hybridizing,sib mating and backcrossing between Re-nd and diapause egg color mutants with the known mutants such as white egg mutant w-2,peach red eye white egg mutant pe and red egg mutant re of B.mori,respectively,and the genetic analysis were also carried out.【Results】The results showed that the non-diapause eggs of F 1 hybrids of Re-nd with Dazao and N4 were both in light red.The non-diapause eggs of F 2 generation of sib mating were in red,light red and light yellow with the ratio of the number of red eggs(including light red eggs)to the number of light yellow eggs basically conforming to 3∶1.The non-diapause eggs of backcross B 1 generation were in red and light yellow,with the ratio of the number of red eggs to the number of the light yellow eggs being basically consistent with 1∶1.The diapause eggs of F 1 hybrids of Re-nd with w-2 and pe were in light brown.The diapause eggs of F 2 hybrid of Re-nd with w-2 were in normal dark brown,light brown,yellow and light yellow with slightly red,while the non-diapause eggs of F 2 hybrid were in red,light yellow with slightly red,orange-yellow and light yellow.The F 2 hybrid eggs of Re-nd with pe were all diapause eggs in normal dark brown,light brown,light yellow with slightly red and red.The hybrid diapause eggs of Re-nd with re in F 1 were in light brown,and those of in F 2 were all diapause eggs in normal dark brown,light brown and red.The diapause eggs in re parents were in red,and no new egg color separation was found in the hybrid eggs of Re-nd with re in F 2.【Conclusion】Through the hybridization and genetic analysis,it was confirmed that Re-nd mutant is an independent dominant inheritance,and the mutant gene of Re-nd should be located in the downstream of the mutant genes of w-2 and pe and may be involved in the process of further metabolism of 3-hydroxy-caninuric acid to ommatins at the later stage of ocular pigment biosynthesis,which is different from the wild-type egg pigment metabolism branch.