关键词: 玉米、郑单22、密度、产量, 玉米、郑单22、密度、产量

Abstract: To understand the genomic differences between Salmonella pullorum and Salmonella gallinarum and to screen Salmonella pullorum-specific sequences that could serve as diagnostic markers, SSH technique was used to compare the genomic differences between S. pullorum C79-13 (tester) and S.gallinarum Sg9 (driver). The tester and driver genomic DNA were digested with Rsa I to give a range of blunt-ended fragments between 100bp and 2000bp. The digested tester DNA was then subdivided into two portions, which were ligated with adaptor 1 and adaptor 2R respectively. Twice hybridizations and two times PCR were performed. The mixture of subtracted DNA fragments were cloned into PCR?2.1 cloning vector and transformed into E.coli DH5α competent cell to construct the subtracted DNA library.The results are as follows: 400 positive clones were obtained; Analysis of 240 clones with PCR shows that all plasmids in the clones contain about 100~2000 bp inserts．The constructed DNA subtractive library lays foundation for screening and cloning relational genes of Salmonella pullorum, and further establishing new system for molecular differentiation .