Molecular evidence on maize specific DNA fragment transferred into wheat through sexual hybridization

Nearly 100 maize specific repeated DNA clones were screened from a maize random genomic library, and used for RFLP analysis of two wheat DH populations from wheat and maize crosses. The result showed that a maize fragment in clone MR64 was transferred into two wheat DH lines, i.e. No.18 in common wheat DHs and No.15 in persicum wheat DHs, in which strong hybridization signals were detected. It is first proved at DNA level that some maize specific DNA can be transferred into wheat DH progenies through fertilization at low frequency. Sequencing revealed that the size of the cloned insert DNA is 695 bp, containing 58% A+T. Southern hybridization to maize genome with several restriction enzymes indicated that MR64 is a dispersed repeat with 2-3 dominant tandem units. Its sequence structure, methylation pattern, copy number and chromosomal distribution were also determined. The possible mechanism of alien DNA transfer was discussed.