Silkworm Aflp Molecular Marker Linkage Map Constructed

The silkworm. Born byv mon.. one of the important economic insects, plays an important role in our country. Constructing the linkage map of silkworm, Bombyx Mon., will lead to much great progress of molecular biology of Bombyx mon. Amplified Fragment Length Polymorphism, i.e. AFLP, is a novel molecular marker technique. having both the high polymorphism of RAPD and the reliability of RFLP. It has a good applied prospect considering the fact that it has been used to construct the linkage map and to map the quantitative trait locus(QTL) widely. AFLP was used to construct a high dense linkage map of Bombyx mon. in the paper. The following are the results: First, total 652 polymorphic loci were amplified using 24 primer combinations. On average, 27.2 polymorphic bands are amplified by one primer combination. The detected fragments are from I OObp to 1 000bp. Second. 33 linkage groups were constructed using 197 polymorphic loci, which was part of the 297 efficient polymorphic loci. The other doesn抰 link each other by our calculation and cant be used to construct the linkage map. The 197 loci account about 66.33% of the 297 efficient loci and 30.22% of the total polymorphic loci. Third. iii the 33 linkage groups. the biggest one is No.4. which has 46 markers: ~lhe smallest has only two markers. The longest linkage group is 89OcM,while the shortest is VII 1/ 1.lcM.The maximum distance between markers is 53.8cM, and te minimum is 0.55cM. Fourth, 33 linkage groups cover about 2692.4cM of the genomics of Bombyx mon. Average length of each linkage group is 81.6cM. In the paper 33 linkage groups are constructed, however Bombyx man, has only 28 chromosomes.It reflects that some of the linkage groups are linked together.But we can not link them together for the absence of the specific markers. Fifth, of the 33 linkage groups.23 has an average distance less than lOcM,and 8 is no less than 10cM and no more than 20cM. Two of them has an average distance more than 2OcN4. Average distance between loci is 9. lcM.And there are 6 markers in one linkage group on average. Sixth, there are 91 loci which map distance is less than lOcMgccounting 46.2% of the 197 loci that enter the linkage map; And the map distance of 64 loci is from 10cM to 20cM. The two account about 78.7% of the 197 loci. The last one, the results show that the length of linkage groi~~ has a positive correlation with the number of markers. That is to say, if there are more markers in a linkage group, the length it has will be longer. Meanwhile there are partial clustering markers. The reason would be that the markers are too close to have recombination. During the process of breeding, via the high dense molecular linkage map and considering the practical needs, ~ can follow the molecular markers and select the phenotype it controlls to reduce the blindness and to improve the breeding efficiency and to accelerate the breeding. Now breeding via marker-assisited selec~on (MAS) has caught the attention. Models of MAS have been constructed in the Brassica napus and watermelon, etc. The qualitative trait locus and quantitative trait locus mapped in 8 cm byx mon. have not so much. The linkage maps of Bombyx man, are mainly the construation of the scaffold. What w...