Abstract: This paper reported the genetic structure analysis for a backcross introgression lines (BILs)of Brassica campestris L. based on a genetic linkage map constructed using a doubled haploid (DH) population. the BILs population with 121 lines derived from a cross between a DH line of a commercial F₁ (Z16) and an oi-ltype B. campestris inbred line (L144) , which was developed by twice consecutively backcrossing using Z16 as a recip ient parent. The characteristics of introgression of L144 in B IL s was analyzed using 97 SSR markers mapped on the DH genetic map. The results showed that the variation of percentage of the donor parent (L144) genome presenting in the BILs was from 0.84% to 35.00% , with an average of 11.31% , consistent with the theoretical expectation of 12.50%. The percentage of the donor parent (L144) alleles presenting in the 25 BC₂ of BIL plants ranged from 1.69% to 27.36% , and the average ratio was 11.03%.

Key words: Brassica campestris, genetic map, double haploid population, backcross introgression lines