家蚕性连锁平衡致死系致死基因的SSR定位

Mapping of the lethal genes in the sex-linkaged balanced lethal silkworm Bombyx mori using SSR markers

家蚕性连锁平衡致死系(S-14)雄蚕的两条Z染色体分别携带有一个非等位、紧密连锁的隐性胚胎期致死基因l1(lethal gene1)和l2(lethal gene2)。两个致死基因的致死时期分别是转青期和G2期。将S-14品系的雄蚕和家蚕P50品系的野生型雌蚕杂交,F1代雄蚕和P50品系雌蚕回交,即P50×(P50×S14)。回交后代雌蛾根据父本(F1代雄蚕)携带l1或l2基因分成两类BC1-l1和BC1-l2,分别用来做l1和l2基因定位。利用公布的家蚕全基因组序列筛选l1基因和l2基因所在Z染色体与P50品系Z染色体间的差异SSR标记,分别获得16个和18个差异性SSR标记,用差异性标记检测BC1-l1和BC1-l2,最终将l1基因定位在Z染色体物理图谱中的19.79Mb位点到染色体末端约2.60Mb范围内,将l2基因定位在Z染色体物理图谱的17.86Mb位点到18.55Mb位点约0.69Mb范围内。

The males of sex-linkaged balanced lethal silkworm strain（S-14） has two non-allelic recessive genes（lethal gene 1,l1 and lethal gene 2,l2） . The two genes are located on two different Z chromosomes and cause death of embryos at body pigmentation stage and end reversal embryo stage,respectively. We firstly hybridized the males of S-14 strain with the females having wild-type genes of P50 strain and then backcrossed the males of F1 with females of P50 strain. A total of 1660 female moths of BC1 generation were divided into two groups,1 100 in BC1-l1 and 560 in BC1-l2 according to the lethal gene carried by these female moths′ fathers-fame moths of F1,respectively. Based on the nucleotide sequence infor-mation from the published physical map of Bombyx mori,we developed 16 polymorphic SSR markers in l1 gene region and 18 polymorphic SSR makers in l2 gene region compared to the allelic region of P50 strain and used these SSR markers and groups of BC1-l1 and BC1-l2 to map the two lethal genes,respectively. Gene l1 was mapped on the region of Z chromosome,covering a physical distance of 2.60 Mb. Gene l2 was fine mapped on the region of Z chromosome,covering a physical distance of 0.69 Mb.