对家蚕第18连锁群隐性基因elp、ch-2和mln测交系的分子定位分析

Molecular mapping of test mapping strain for 18^(th) linkage group recessive genes elp, ch-2 and mln in silkworm (Bombyx mori)

家蚕长形卵(elp)、第二隐性赤蚁(ch-2)、暗化型(mln)均为第18染色体上的隐性突变,在经典连锁图谱上的顺序和遗传距离已经排定。文章采用正常卵、正常黑蚁及正常白蛾品种P50与包含此3个隐性突变的三隐性测交系W18组配正反交群体,F1回交W18后获得回交群体(P50×W18)♀×W18♂和W18♀×(P50×W18)♂,分别记作BC1F和BC1M,利用已构建的家蚕SSR分子连锁图谱和根据家蚕基因组精细图设计的STS标记,对这3个突变基因elp、ch-2、mln进行了分子定位研究,并根据家蚕基因组精细图,将第18连锁群的经典遗传图、分子连锁图和基因组物理图进行了对应。整合后的图谱遗传距离为94.2 cM,突变基因和分子标记的排列顺序分别与形态标记连锁图和基因组精细图相一致,研究结果对家蚕第18染色体上其他突变的定位与克隆有重要的借鉴作用。

The ellipsoid egg, the second recessive gene of chocolate larvae, and melanism are controlled by three reces- sive genes, elp, ch-2, and mln in silkworm, respectively. Their order and genetic distance have been scheduled in estab- lished linkage group. Owing to lack of crossing over in females, the reciprocal backcrossed F1（BC1） progenies were bred for linkage analysis using the wild type silkworm strain P50（＋elp＋ch-2＋mln/＋etp＋ch-2＋mln） and W18 with ellipsoid egg, the sec- ond recessive gene of chocolate larvae, and melanism （elp ch-2 mln / elp ch-2 mln）. In this research, we mapped three mu-tant genes, elp, ch-2, and mln on the chromosome 18 based on the SSR linkage map and STS markers designed based on silkworm genome sequence. The established linkage group, molecular linkage group, and the physic map of chromosome 18 had been corresponded. The genetic distance for this chromosome in this research was 94.2 cM, and the order of the mutants and molecular markers were consistent with the established silkworm linkage maps and the fine genome sequences. This research will lay important bases for map-based cloning for other mutants on chromosome 18.