MAS In Breeding The High Tolerance To Fluoride And Scaleless Wings Of Silkworm Strains And Mapping The Susceptible Geneto AcMNPV In Silkworm

With the development of economy, air pollution is becoming a serious problem beacouse in some regions. Fluoride is one of the main components in polluted air,it is harmful not only to human beings but also to mulberry trees and silkworms. Fortunately,we have discovered the mutant, Dtf?dominant toleranceto fluoride? in silkworms. And this mutant has been mapped using simple sequence repeat?SSR? and sequence tag site?STS? markers. Dtf controls tolerance to fluoride. The larvae can survive even when they are fed with mulberry leaves treated with 200 mg/kg of NaF solution, but the larvae of highly susceptible silkworm strains will die even at a concentration as low as 50 mg/kg.There is a layer of scales on the surface of the wings of silkworm moths, which is a typical characteristic for lepidopteran adults. In silkworm egg production farms, when the moths hatch, there are numerous airborne scales.This scales will be floating in the air and environmental pollution, harm people's health, reassure workers can't normal work.Fortunately,we also have discovered the mutant, nlw?scaleless wings? in silkworms.The allele now is recessive, and has been mapped using simple sequence repeat?SSR?.We used silkworm strain T6 and U13 as parents, qingsong as recurrent parent. For the cross-over experiments, a female of the Jingsong strain was crossed with a male of the T6 strain, and then?Jingsong x T6? females were mated to the U13 strain. Jingsong females were then crossed to?Jingsong x T6? x U13 to obtain BC1 and other backcross?BC? generations?six in total? males in order to evaluate their economic characteristics. In each generation, SSR and STS markers, located on either side of Dtf, S1214 and S121201 and nlw, S1305 and cash2 p, were used to detect the genotype of male moths after they mated with Jingsong females.When backcrossing generations, only the heterozygous individuals from Jingsong and T6 in S1214 and S121201 and Jingsong and U13 in S1305 and cash2 p were used. Otherwise, Jingsong-type homozygous animals were discarded. Self-mating within a generation was carried out in the BC6 generation, and these offspring were fed with 200 mg/kg NaF-polluted mulberry leaves. Scaleless-wing moths with good economic characteristics were selected from the surviving individuals and were self-mated to generate the next generation?BC₆F₃?, and molecular markers were used to select the individuals that were homozygous at both the Def and nlw sites. Thus, a new silkworm strain with good economic characteristics, high tolerance to fluoride, and scaleless wings was developed.Autographa californica multiple nucleopolyhedrovirus?AcMNPV?, the member of the virus family Baculoviridae, could infect a relatively wide number of hosts. We have found that several silkworm strains were susceptible to recombinant AcMNPV by intrahemocoelical infection, and that the susceptibility to AcMNPV was controlled by one recessive gene, sav. Based on these results, the non-susceptible silkworm strain C108 and susceptible silkworm strain P50 were used to construct reciprocal mapping populations BC1 F and BC1 M respectively. The individuals were judged for their susceptibility by using fluorescence microscope after they were injected of recombinant AcMNPV AcA3egfp?EGT per larva and reared for 3 days. Strong green fluorescence was observed on susceptible larval body surface.The STS markers were designed based on the silkworm genome sequences, and sav was mapped to chromosome 3 owing to the lack of crossing over in female silkworm. This linkage map was constructed by BC1 M, it has a genetic distance of 48.7cM, with sav mapped at 37.6 cM. The sav gene mapped between t T0399 and T03147, they are 5.1 cM and 0.4cM away from sav respectively.