Study On The Application Of Molecular Marker Technique In Breeding Wheat For Powdery Mildew Resistance And Constructing DNA Fingerfrinting Of Wheat

Molecular marker technology is a new type of genetic marker system which had been developed since mid eighties of the century under the rapid progress of the theory and technique in molecular biology. Though experienced only a short time of more than ten years since its birth, molecular marker techniques have been widely used in viarious aspects of plant genetics and breeding, such as in constructing molecular genetic maps, tagging and cloning genes, marker-assisted selection for important agronomic traits, and in studying on evolution and relationships of species etc. In this research project, molecular marker techniques such as RFLP, RAPD, SCAR and ISSR were used in the study of finding DNA markers and marker-assisted selection for powdery mildew resistance genes of wheat and in DNA fingerprinting of wheat cultivars and lines. The program involves four aspects as follows: I . Screening of RAPD markers tightly linked to wheat powdery mildew resistance gene Pm6 Wheatltimopheevii introgression line IGVI-463 containing wheat powdery mildew resistance gene Pm6 possesses smaller introgressed chromosome fragment transferred from timopheevii, so it can be regarded as near-isogenic line (NIL) of the recurrent parent Prins containing no any other wheat powdery mildew resistance genes. The random amplified polymorphic DNA (RAPD) analysis was made in the Pm6 NIL with seven hundred random primers. It was found primer OPV2O could produce a 2kb reproducible fragment only in resistant near-isogenic line IGVI-463 and absent in Prins, the polymorphic fragment was designated as OPV202~. Further experiments verified the marker OPV2O2OOO was always present in all other introgression lines containing Pm6 and the donor parent timopheevii and absent in the control line Prins. Using F2 mapping population from a cross of IGVI-463 X Prins. Pm6 was shown to be tightly linked to the marker OPV2O20~J at a genetic distance of 3.0 ?2.2cM. The marker was successfully used in detecting the presence of Pm6 in different genetic background. It will be the basis of marker-assisted selection for Pm6 and of cloning Pm6 gene. II. Application and stability analysis of RAPD and SCAR markers in the selection for powdery mildew resistance gene Pm21 of wheat Wheat-Haynaldia villosa translocation line 6VS/6AL developed by Cytogenetic Institute of Nanjing Agricultural University contains the most effective wheat powdery mildew resistance gene Pm21 in China and even in worldwide. In order to make full use of the resistance gene resources in breeding for powdery mildew resistance of wheat, our institute has been making its best to transfer the gene into elite cultivars through backcrossing. To improve the efficiency of selection, we evaluated the stability and application value of the RAPD marker OPHI ~ and SCAR marker converted from it in the marker-assisted selection for Pm21. Many experiments by PCR analysis showed SCAR marker is more stable and reproducible than the R.APD marker, and SCAR reaction is insensitive to PCR conditions but the RAPD is sensitive which need better expertise, however, OPH171~ is a fairly stable marker which was verified by different researchers. The results shows SCAR marker converted from RAPD marker is an ideal marker system for marker-assisted selection characterized by its simplicity, rapidness and is worth to popularize. LII. Markers-assisted selection and pyramiding for powdery mildew resistance genes in common wheat...