Genomic in situ hybridization analysis for identification of introgressed segments in alloplasmic lines from Zea mays x Zea diploperennis.

In this study, the tested four alloplasmic inbred lines, a2-4, a2-5, b1-1 and b2-1 were propagated from the same disease resistant individual in the parthenogenetic progenies of Zea mays L. cv. Lu 9 x Zea diploperennis (DP). All the lines except a2-5 were resistant to Helminthosporium turcium Pass and H. maydis Nisik. Introgressed DP segments in these lines were detected by both Southern hybridization and genomic in situ hybridization (GISH). The results of Southern hybridization showed that DP species-specific DNA sequences had been introgressed into the genomes of alloplasmic lines. The Southern hybridization band patterns in all of the tested lines were consistent with those of DP. Genomic in situ hybridization (GISH) signals were detected on 7 different chromosome pairs in lines a2-4 and a2-5, on 5 chromosome pairs in b1-1 and on 4 chromosome pairs in b2-1. The features of introgression, and disease resistant genes in the introgressed segments, as well as the gene silence or elimination in some alloplasmic lines are discussed.