Abstract

The near isogenic lines (NILs) of non-susceptible to DNV-Z were bred through backcrossing successively using L10 as donor parent and Js as recurrent parent. The homozygosity of the NILs was detected using the SSR markers from the SSR linkage map. The results showed that the ratio of the linkage groups from the recurrent parent in the NILs increased rapidly along with the increase of the backcrossing generations. After 6 generations of backcrossing, it was selfed and was fed with DNV-Z. The linkage groups of 9 of the 5 BC₆ pairs, whose 1/4 offspring were non-susceptible to DNV-Z, were all replaced by the recurrent parent except the linkage group that heldnsd-Z, and only part of one linkage group from the other one individual had not been replaced. According to the markers linked to nsd-Z, Fl0316 had not been replaced in all of the 10 individuals, but crossover happened in 2 individuals between Fl0568 andnsd-Z.

Key words: Silkworm, Non-susceptible to DNV-Z, Near Isogenic line, SSR marker, Homozygosity and Linkage group.