| Maize sown in 25 million hectares is second to rice as the most important crops in China. The losses in maize production and poor quality grain have been influenced by more than 30 kinds of more common maize diseases. It is necessary to develop near isogenic lines and inbred lines with the resistance genes used in the research on inheritance of resistance and resistant breeding by marker assistant selection with conventional breeding instead of conventional breeding. The conclusion was as follows:Firstly, the breeding program of marker assistant selection with conventional breeding was done. The Susceptible inbred line Mo17 was used as recurrent parent, and the resistant inbred line Siyi as nonrecurrent parent. 4 flanking markers were used for selecting for the two resistance genes and 129 SSR markers that were polymorphism between Siyi and Mo17 with phenotypic selection were used for selecting for the genetic background of Mo17. Crossing once, backcrossing four times, selfing once, then got the NILs with the gene on chr.3, the one on chr.6 and these two genes in 2005, while 22 NILs with one and a few markers were obtained. Two complementary dominant genes conditioning the resistance, with a new genetic model, of the elite maize inbred line Siyi were confirmed by the genetic analysis based on BC3F1 from the combination of Siyi and Mol7.Secondly, the resistance gene to maize dwarf mosaic Mdm1 in the inbred line Pa405 was tagging by microsatellite markers, the linkage distance between the marker bnlg1600 and the gene is 3.2 cM. The two resistance genes to maize dwarf mosaic, Mdml and the gene mdm (t) in the lines Huangzaosi, were pyramided by MAS with Pedigree method. 5 inbred lines with high resistance to MDMV developed.Thirdly, the two resistance genes to MDMV in the inbred line Siyi and the resistance gene to Stalk Rot (pythium inflatum) Rpil in the line 1145 were pyramided. 15 inbred lines with high resistance to MDMV and stalk rot developed.
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