An amplified fragment length polymorphism map of the silkworm

The silkworm (Bombyx mori L.) is a lepidopteran insect with a long history of significant agricultural value. We have constructed the first amplified fragment length polymorphism (AFLP) genetic linkage map of the silkworm B. mori at a LOD score of 2.5. The mapping AFLP markers were genotyped in 47 p rogeny from a backcross population of the cross no. 782 x od100. A total of 1248 (60.7%) polymorphic AFLP markers were detected with 35 PstI/TaqI prim er combinations. Each of the primer combinations generated an average of 35 .7 polymorphic AFLP markers. A total of 545 (44%) polymorphic markers are c onsistent with the expected segregation ratio of 1:1 at the significance le vel of P = 0.05. Of the 545 polymorphic markers, 356 were assigned to 30 li nkage groups. The number of markers on linkage groups ranged from 4 to 36. There were 21 major linkage groups with 7-36 markers and 9 relatively small linkage groups with 4-6 markers. The 30 linkage groups varied in length fr om 37.4 to 691.0 cM. The total length of this AFLP linkage map was 6512 cM. Genetic distances between two neighboring markers on the same linkage grou p ranged from 0.2 to 47 cM with an average of 18.2 cM. The sex-linked gene od was located between the markers P1T3B40 and P3T3B27 at the end of group 3, indicating that AFLP linkage group 3 was the Z (sex) chromosome. This wo rk provides an essential basic map for constructing a denser linkage map an d for mapping genes underlying agronomically important traits in the silkwo rm B. mori L.