Abstract: Wide hybridization is a most widely used technique in crop breeding programs. In addition to karyotypically stable crosses which give rise to hybrid plants, karyotypically unstable crosses, i. e., the chromosome elimination systems, can be used to produce doubled haploid (DH) plants through embryo rescue and doubling treatment. However, 2 ～5 % of the wheat DH progenies from wheat × maize crosses have morphological variations, which are incompatible with their theoretical homogeneity. Recently, it was proved at DNA level that some maize-specific DNAs were transferred into wheat DH progenies through fertilization between wheat and maize.