Mapping Of The Restore Genes Of C-cytoplasmic Male Sterility And The Resistance Gene To Maize Dwarf Mosaic Virus

Cytoplasmic Male Sterility (CMS) is a kind of common phenomenon in higher plants, it cannot produce viable pollen, but its female fertility is unaffected. Three types of male sterile cytoplasm in maize designated as T, C and S, can be classified by the specific nuclear genes, which suppress the male sterile effects of these cytoplasm and restore pollen fertility. The restorer genes and genetics of CMS-C have not been understood very clear because of its complex genetic background. The reports about the chromosomal location of restorer gene Rf4 are different, and the chromosomal location of restorer gene Rf5 and Rf6 haven't been studied.Using restorer lines Fengkel, A619, sterile lines CMS-C-237, CMS-C-Mol7 and its progeny, we find Fengkel has two duplication gene Rf4 and Rf5, and A619 has one restorer gene Rf4. The restorer gene Rf4 is mapped on chromosome 8 through SSR method, 25.4cM from the primer bnlg2307; and the restorer gene Rf5 is on the long arm of chromosome 5, links with the primers bnlg1711, bnlgl346 and phi058, the genetic distance from three primers are 7.51cM, 1.68cM, 9.87cM.Maize dwarf mosaic virus (MDMV) is the most widely occurring viral disease of corn in the world; it can reduce grain yield near 50% in some year. It is difficult to avoid MDMV because it has many kinds of virus strains (including A, B, C, D, E, F, 0 and KSI), and transmits through inoculation, aphid and seed. Using resistance hybrids is the best way to control maize dwarf mosaic now. China is a higher occurring country, of the two major strains of the virus in our country; strain B has a wider geographical occurrence than SCMV.The inheritance of resistance to MDMV is very complex. Many studies have been conducted to elucidate the type of gene function; the conclusions draws from the results of these studies are different. Some researcher concluded that resistance to MDMV had one or two dominant genes, reciprocal chromosomal translocation and RFLP method had been used to map the dominant gene Mdml, all studies were in agreement that Mdml localized on chromosome 6.Corn inbred Huangzaosi, Pa405 (resistance to MDMV-B) and Mo 17, 8112 (highly susceptible to MDMV-B) was chosen for this study. Through genetic analysis, Huangzaosi has a major gene and some quantitative genes that resist MDMV-B, the main resistant gene is a new recessive gene named mdm2. Using reciprocal chromosomal translocation lines with genetic marker wxwx, mdm2 gene is mapped on chromosome 6.Through SSR method, mdm2 is localized on the long arm of chromosome 6, links with SSR primer bnlg1867, bnlg391 and phi077, the genetic distances with the three primers are 9.56cM, 6.72cM, and 4.74cM...