Studies On Molecular Markers Linked To Powdery Mildew Resistance Genes In Wheat

Powdery mildew is one of the most serious diseases affecting wheat yield. Wheat production of our countiy faces with single resistant source and unrational distribution of resistance genes, and lots of effective resistance genes had not been used as fully as possible. So, it is necessary to improve resistant sources known and research for new effective resistant genes. This study was to found AFLP molecular markers linked to Pml8 and an unknown resistant gene in Am6 by using SSR and AFLP techniques. This will set up a good base for using molecular markers linked to resistant genes to select-assistance and for cloning powdery mildew resistance genes. The main results are summaried as follows:1. 164 AFLP primer combinations were used to find molecular markers linked to PmlSAS of them appeared polymorphism between resistant DNA pool and susceptible DNA pool. The specific DNA fragments cosegregated with PmlS were amplified by 3 of primer combinations. They were 360bp (18M1), 210bp (18M2) and 315bp(18M3) DNA fragment produced by P14M77, P15M35 and P13M57 respectively.2. 182 primer combinations were used to analyze AFLP markers linked to powdery mildew gene of Am6 and 29 primer combinations showed polymorphism between resistant DNA pool and susceptible DNA pool. The specific DNA fragments 6MK 6M2 and 6M3 were amplified which linked to the powdery mildew gene of Am6. The. three primer combinations were P34M56(270bp),P16M81(450bp) and P80M75(465bp) respectively. The genetic distances between the gene and three DNA fragments were O.ScM, 5.1cM and 7.9cM respectively. 3. The 210bp DNA fragment(18M2) amplified by P15M35 was purified after second PCR and ligated with vector, then it was sequenced and compared in EBI data bank. The result showed that no plant nucleotide sequence was homology with it, so it may be a new nucleotide sequence.