Genetic Analysis And Molecular Mapping Of Stripe Rust Resistance Gene(s) In Three Wheat Lines

Stripe rust (or yellow rust), caused by fungus Puccinia striiformis f. sp. tritici (Pst), is one of the most important foliar diseases of wheat. Characterization and utilization of novel resistant genes are the most effective, economic and environmentally-friendly approach to control the disease.This research main focus on:(1) QTL mapping for resistance to stripe rust (Puccinia striiformis f. sp. tritici) in common wheat accession PI 182103; (2) Molecular mapping and allelic analysis stripe rust resistance gene YrSP in wheat genotype AvSYrSPNIL; (3) Identification and genetic mapping of a recessive gene for resistance to stripe rust in wheat line LM168-1. The following results were obtained.(1) QTL mapping for resistance to stripe rust (Puccinia striiformis f. sp. tritici) in common wheat accession PI 1821031. The results show PI 182103 not only has seedling resistance, but also has high temperature adult-plant resistance. A total of 184 recombinant inbred lines from cross AvS/PI 182103 and SSR/SNP markers were used to map the quantitative trait loci (QTL) for resistance genes of PI 182103;2. Three QTL of seedling resistance to PST-100 and PST-114 were identified and named as Qyr.PI182103.wgp-2AS, Qyr.PI182103.wgp-5BS and Qyr.PI182103.wgp-3AL. Qyr.PI182103. wgp-2AS can explain the phenotypic variance to PST-100 and PST-114 is 8.22% and 4.95%, respectively. Qyr.PI182103.wgp-5BS could explain the phenotypic variance PST-100 and PST-114 is 14.20% and 8.22%, respectively. Qyr.PI182103. wgp-3AL could explain the phenotypic variance PST-100 and PST-114 is 8.07% and 5.38%, respectively;3. Three QTL for stripe rust resistance of adult plant were detected, and designated as Qyr.PI182103.wgp-7BL, Qyr.PI182103.wgp-5BS and Qyr.PI182103.wgp-4DL, respectively. Qyr.PI182103.wgp-7BL, Qyr.PI182103.wgp-5BS could be detected steadily in two locations, but Qyr.PI182103.wgp-4DL only detected in Mt.Vernon. Qyr.PI182103.wgp-7BL could explain the phenotypic variance across five environments is from 12.60% to 29.39%. Qyr.PI182103. wgp-5BS could explain the phenotypic variance from 8.22% to 57.9%. Qyr.PI182103.wgp-4DL could explain the phenotypic variance in Mt.Vernon from 2.54%to 11.75%;4. A completely set of Chinese Spring (CS) nulli-tetrasomic lines,7B-CS ditelosomic lines, and 7BL-CS deletion lines were used to map the Qyr.PI182103.wgp-7BL on 7BL 0.14-0.4 regions;5. Allelic analysis, resistance test and molecular marker test results showed Qyr.PIl82103.wgp-7BL was different from Yr2, Yr6, Yr39, Yr52, Yr59, YrZH84, YrC591 on 7B chromosome, it could be a new stripe rust resistance gene;6. Polymorphism test of markers linked with Qyr.PI182103.wgp-7BL in 74 wheat genotypes showed, none of the genotypes were found to have both target bands.(2) Molecular mapping and allelic analysis stripe rust resistance gene YrSP in wheat genotype AvSYrSPNIL1. To map YrSP, its near-isogenic line was backcrossed to the recurrent parent, Avocet Susceptible (AvS). Genetic analysis of the F1, F2, F2:3and BC1 progenies confirmed the single dominant gene. A total of 182 F2 plants and their derived F23 lines were phenotyped with an avirulent Pst race and genotypes with simple sequence repeat (SSR), single-nucleotide polymorphism (SNP), and sequence tagged site (STS) markers. A linkage map was constructed with 3 SSR,17 SNP and 3 STS markers covering 27.6 cM. Markers S3 and dp269 were 0.4 and 1.8 cM from YrSP, respectively;2. A completely set of Chinese Spring (CS) nulli-tetrasomic lines,2B-CS ditelosomic lines, and 2BL-CS deletion lines located YrSP on 2BL 0-0.5 regions;3. Allelic analysis, resistance test and molecular marker test results showed YrSP is different from Yr5, Yr7, Yr43, Yr44, Yr53 it is a new stripe rust resistance gene;4. Polymorphism test of markers flanked YrSP in 77 wheat genotypes showed,2 gegenotypes:OR2080156H and OR2080229H were found to have both target bands.(3) Identification and genetic mapping of a recessive gene for resistance to stripe rust in wheat line LM168-11. Wheat line LM168-1, which was derived from a cross between common wheat Chuannong 16 and Milan, has good adult-plant resistance to stripe rust based on field tests of several years. To elucidate the genetic basis of resistance, LM168-1 was crossed with susceptible variety SY95-71. Parents and F1, F2, BC1 and F2:3 progenies were tested in field in 2009 to 2011 inoculated with predominant Pst races of China. The genetic analysis showed that resistance to stripe rust in LM168-1 was controlled by a single recessive gene, temporarily designated as yrLMl 68;2. Simple sequence repeat (SSR), resistance gene analog polymorphism (RGAP) and target region amplification polymorphism (TRAP) techniques were used to identify molecular markers linked to the resistance locus. Finally, a linkage group consisting of two SSR, four RGAP and five TRAP markers was constructed for yrLM168. The closest markers R1 and R2 flanked the resistance gene locus at 2.4 and 2.4 cM, respectively. Furthermore, two SSR markers Xwmc59 and Xwmcl45 assigned the gene on chromosome 6A.These resistance genes should be useful in stripe rust resistance breeding programs, and the closely linked markers could be used for rapidly transferring these genes to wheat breeding populations.