Wheat Powdery Mildew Resistance Gene Pm16 Ssr Markers And Multi-gene Accumulated Body Of Marker-assisted Selection

Powdery mildew, caused by Erysiphe graminis (Blumeria graminis) f.sp. tritici, is one of the most destructive wheat diseases throughout the word and China. It has been proved that the most effective method to suppress the pathogen is to breed resistant cultivars and pyramiding different resistant genes into a genotype is one way to breed wheat cultivars with durable and broad-spectrum powdery mildew resistance. Therefore the exploitation of powdery mildew resistant (Pm) genes, which including Pm gene's marking, location and molecular-marker aided selection, would benefit breeding the effective powdery mildew resistant cultivars.One of the most effective resistant Pm genes is Pm16 that comes from wild tetraploid wheat (Triticum dicoccoides), is immune to all the pathogen races prevailing in Northern China and was widely regarded as locating on chromosome 4A on the basis of monosomic analysis. In this study, the 156 F2 individuals and their parents, Chancellor (susceptible mother) and 70281 (resistant father) carrying Pml6 were inoculated with powdery mildew strain No. 15 at seedling stage to assess their resistant ability. The resultsshowed that the resistance of 70281 was controlled by a pair of single dominant genes, it was Pm16.Twenty of 156 DNA samples extracted from the F2 population were pooled into two separate groups for bulked segregant analysis (BSA ). Toidentify the molecular markers linked to the resistant gene, 65 sets of microsatellite primer were screened between the parents and progenies. The results indicated, on 4A chromosome of wheat and the 3rd chromosome of rice, there was no PCR polymorphism between the resistant pool and the susceptible ones with 31 sets of primer. However, three SSR markers located on 5BS chromosome of wheat were found linked with Pml6. The locus order on linkage map was Pml6-xgwml59-Borcl09- Borc004 and the 3 genetic distance intervals were 5.3cM, 23.7cM and 2.2cM in order. Therefore the Pml6 was newly located on 5BS chromosome instead of the former considered 4A chromosome of wheat.The 49 DH3 seedlings, which potentially contain the multiple Pm resistant genes were tested by the analysis of STS-PCR marker of Pm4b, SCAR-PCR marker Pml3 & Pm21 and Biochemical marker of Pm12, The results showed that senven plants confer with Pm4b+ Pml2+ PmV, one plant with Pm4b+ Pm13+ PmV, three plants with Pm12+ Pm4b, six plants with Pm4b+PmV, tow plants with Pml2+PmV, tow plant with Pml3+ PmV respectively. We will validate the plants with identified genes using gene-to-gene method and genetic analysis.