MOLECULAR EVIDENCE ON MAIZE SPECIFIC DNA FRAGMENT TRANSFERRED INTO WHEAT THROUGH SEXUAL HYBRIDIZATION

Nearly 100 maize-specific repeated DNA clones were screened from a mai ze random genomic library, and used for RFLP analysis of two wheat DH populations from wheat and maize crosses. The result showed that a mai ze 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 whic h strong hybridization signals were detected. It is first proved at DN A level that some maize-specific DNA can he transferred into wheat DH progenies through fertilization at low frequency. Sequencing revealed that the size of the cloned insert DNA is 695 hp, containing 58% A + T . Southern hybridization to maize genome with several restriction enzy mes indicated that MR64 is a dispersed repeat with 2-3 dominant tandem units. Its sequence structure, methylation pattern, copy number and c hromosomal distribution were also determined. The possible mechanism o f alien DNA transfer was discussed.