| Rearing silkworm with artificial feedings(AD)is the developmental direction in the future sericulture industry,but the technology can’t meet the practical demands because of lacking suitable silkworm strains feeding on AD.Explorating the genetic modes and the molecular mechanism has important theoretical and practical significances in the selection of silkworm strains feeding on AD.Therefore,we utilied the silkworm strains with obviously different feeding habits as the experimental material in this study to research the genetic pattern of different silkworm strains on AD,and locate related genes with SSR markers and Map-based cloning technology,and also used semiquantitative polymerase chain reaction(sq-PCR)technique to detect the differences in mRNA experession level between good feeding varieties,Zhongguang 04(ZG04),and bad feeding varieties,Lu7(L7),of the 14 predicted genes.The main results are as follows:1.We utilized 3 pairs of silkworm strains with significantly different feeding habit on AD,and made them to combine P1,P2,F1,F2 and BC1,and gained 10 generations.We investigated the setae dispersion rates of newly hatched silkworms fed with AD after 36?h,and analyzed the genetic pattern with the Joint Scaling Test.The results indicated that good and bad feeding habit strains of Jingsong A and Jingsong B displayed additive-maternal influence genetic pattern.It was dominant-additive-maternal pattern between polytrophic strain,Zhongguang 04,and bad feeding habit strain,Lu7,on AD.2 We made the ZG04 and L7 to combine F1 and BC1F(ZG04×L7)× L7 and BC2F[(ZG04×L7)×L7]×L7,then analyzed positioning and linkage of genes related with AD habits using SSR technology,The results indicated that 2 SSR marker S0709 and S0710 which were in the seventh linkage groups linked with AD habits.The genetic distance was 1.1 cM.Five new polymorphism SSR makers were obtained find by the SSR Hunter 1.3software.According to the results of PCR amplification with the 5 new SSR markers in BC2 F population,the low feeding individuals resembled L7.Based on the information in KAIKObase Silkworm Database,the nucleotide sequence and prediction genes between S0709-S0710 were analyzed,and 14 prediction genes were found between S0709 and S0710.Based on the marker loci and gene loci,a linkage map between 14 genes and 7 molecular markers was drawn.The genetic distance of genetic linkage map was 226720 bp,and the distance between Gene8 and S3 markers was nearest to 241 bp.3 Using silkworm of newly-hatched,and 2nd instar larvae,3rd instar larvae,and the 3rd instar larvae head of ZG04 and L7 as material,we measured expressional level of 14 genes between S0709-S0710 by sq-PCR technique to measure expression of 13 genes in S0709-S0710.The results show indicated that no significant difference in the expression of 10 genes in ZG04 and L7,but Gene1 and Gene3,but in ZG04,the expressional level are were higher than that of in L7 silkworm among of newly-hatched silkworm,2nd instar larvae,3rd instar larvae,and the 3rd instar larvae head.Gene4 was not expressed in ZG04,but expressed in L7 at different ages.The specific functions of these genes and their relationship with diet should be further studied. |
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