Molecular Marker Of Wheat Resistance Gene Against Stripe Rust, Powdery Mildew And Leaf Rust

Wheat is one of the three leading cereal crops, with over 600 million tonnes being havested annually in the world. It has important significance to ensure high-yield. However, Stripe rust, powdery mildew and leaf rust are three of the most destructive diseases of wheat and cause serious yield loss in wheat growing regions with temperate climates resulting in huge economic loss. Although chemical control and some cultivation measures, to a certain extent, could reduce these losses, it has been proved that the most economical, effective and environmentally safe way to control these pathogenes is to breed resistant cultivars. Due to the high variability of pathogenes, this work could not be completed once and for all. A disease-resistant cultivar which planted alone and extensively may lost its resistance in a relatively short period because of the epidemic of a new virlence physiological race. Extensively collection and identification of resistance resources and genes is the premise of wheat breeding for disease resistance. The purpose of this study is to screen some genetic resources with resistance against stripe rust, and to identify molecular markers linked to resistance genes against stripe rust, powdery mildew and leaf rust. The results were as follows:1. The resistance of 216 cultivars (or lines) and 147 introgression lines were scored at adult plant stage. Among the 216 cultivars (or lines), there are 28 cultivars of immune resistance,73 cultivars of high resistance,57 cultivars of middle resistance and 10 cultivars of slow rust resistance. These materials can be further used for resistance breeding against stripe rust. At the same time,16 introgression lines with resistance and good appearence of other agronomic traits also were identified in this study. These materials with the genetic background of wheat cultivar Yanzhan 1 can be used as the source for resistance breeding and to study the resistance gene when combined with Yanzhan 1 to form near-isogenic lines.2. Association analysis of the resistance against stripe rust of 153 cultivars and 308 SNP markers designed by our laboratory was conducted. Through the independence test of the contingency table analysis, six SNP markers were identified to be associated with the disease resistance at the 0.01 probability level. Moreover, variance analysis of the resistance of cultivars grouped by these six SNP markers showed significant or extremely significant difference.3. Genetic analysis and molecular marker of a powdery mildew resistance gene in the lines GRY19 were conducted. The genetic analysis result showed that the resistance of GRY19 is controlled by a single dominant gene derived from Elytrigia intermedium. Five genetic markers, Xgwm297, Xwmc335, Xwmc364, Xwmc426 and Xwmc476 on 7BS chromosome, were identified to be linked with the resistance gene in an F2 population of Mianyang 11/GRY19. The loci order is Xwmc426-Xwmc335-Pm40-Xgwm297-Xwmc364-Xwmc476 with genetic distance of 5.9 cM,0.2 cM,0.7 cM,1.2 cM and 2.9 cM, respectively, which were consistent with the published maps. The resistance gene transferred from Elytrigia intermedium into wheat line GRY19.was novel, and was designated Pm40. The close flanking markers will enable marker assisted transfer of this gene into wheat breeding populations.4. QTL analysis of adult plant resistance against leaf rust of wheat international mapping population Synthetic x Opata 85 was conducted. According to the infection type, five QTLs were detected and explained 62.63% phenotypic variation. Meanwhile, three QTLs were detected according to severity and explained 41.65% phenotypic variation. Among them, QLr.caas-4B and QLr.caas-3B were the QTL loci detected by both infect type and severity, and they showed the largest genetic effect. According to their location on genetic map, QLr.caas-4B might be Lr31, QLr.caas-3B might be Lr27 and QLr.caas-7D might be Lr34, QLr.caas-6A might be consistent to the QTL reported by William H. M. et. Therefore, QLr.caas-1A and QLr.caas-5A were new QTL loci.5. The haplotype of Lr34/Yrl8/Pm38 were detected in 133 cultivars collected by our laboratory for breeding. In this study, a allele specific PCR primer Prsnp1 was designed to identify the A/T SNP difference in the 4th intron. Prsnp1, cssfr5 and cssfr6 were proved to be effective in the detection of A/T SNP in the 4th intron, TTC's Indel in the 11th Exon and C/T SNPs in the 12th Exon. As a result,44 cultivars which came from seven of the eleven wheat regions showed to be the+Lr34 haplotype.