Dissertation > Agricultural Sciences > Crop > Cereal crops > Wheat > Wheat

Construction of Molecular Linkage Map of (Wangshuibai×Alondra’s) RIL Population and Mapping of ESTs Related with Fusarium Head Blight Resistance

Author WangJia
Tutor WangXiuE
School Nanjing Agricultural College
Course Crop Genetics and Breeding
Keywords Fusarium head blight Molecular Marker Linkage Map QTL EST
CLC S512.1
Type Master's thesis
Year 2011
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Fusarium head blight (FHB) or scab is an important disease of wheat which causes se-rious threat to grain yield, quality and food safety. Selection of wheat cultivars with FHB resistance is the most economical and effective means for FHB control. A wheat landrace, Wangshuibai, has been proved to be one of the important genetic resources for the im-provement of FHB resistance. In the present study, to further clarify the molecular mecha-nism of scab resistance of Wangshuibai’s, and to accelerate the effective utilization of scab resistance in wheat genetic improvement, a RIL population derived from a cross between Wangshuibai and Alondra’s was constructed. The population was used to constructe a mo-lecular marker based linkage map. Based on the evaluation data using different evaluation methods (single floret-inoculation, spray-inoculation, and natural infection in the severe epidemic areas) and different Fusarium strains with different DON-producing capabilities (B4-1、F0609、tri5), QTL related to FHB resistance of Wangshuibai was mapped. Ac-cording to the results of expression profile induced by the Fusarium gramiearum by Af-fymytrix GeneChip of wheat, primer pairs were designed according to those ESTs se-quences or cloned genes which showed differentially expression pattern (Xiao,2010). These ESTs were then mapped to the linkage map. The main results obtained in this re-search are as follows:1. The amplification data of the 193 polymorphic markers in the population was further used for linkage analysis using the Joinmap 4.0 software. A genetic map consisting of 35 linkage groups which belonged to the 21 wheat chromosomes and 162 molecular markers was constructed. The map covered a total of 1016.9cM of the wheat genome and the aver-age genetic distance was 11.0cM.19 of the 193 polymorphic markers was new designed and synthesized by our laboratory, and 15 were mapped on the genetic map established in this study. Theχ2 analysis of the 193 polymorphic markers revealed that 68 markers were skewed segregated in the population, and the segregation ratio was 35.2%. 2. Based on the established molecular linkage map and the evaluation data of FHB re-sistance, QTL analysis was performed using a joint composite interval mapping method of the Windows QTL Cartographer 2.5 when the LOD threshold is 2.0. A total of thirty-five QTLs related to FHB resistance were detected, which involved 13 chromosomes such as 1A、1B、2A、2B、2D、3A、3B、3D、4D、5B、6A、6B、7D. Using the resistance data from the spray-inoculation of the strain B4-1 in 2011, a QTL related to FHB resistance was detected on chromosome 3B between markers Xwmc505-Xwmc615, and its contribution ratio was the most as much as 20.49%. QTLs related to FHB resistance near marker Xgwm533 on chromosome 3B were repeatedly detected using the evaluation data from the spray-inoculation of the strain B4-1 in 2010 and 2011, and the evaluation data from the spray-inoculation of the mixture strain in 2007, and their average contribution ratio was 10.02%.3. Eleven primers derived from ESTs associated with FHB resistance were screened for polymorphisms between the two parents of the RIL population, and 10 were mapped on the genetic map established in this study. The genetic distance between EST516 and the FHB resistance QTL on chromosome 3B near marker Xgwm533 was 13.1cM. The average genetic distance between EST463 related with the hypothetical protein and the FHB resis-tance QTL on chromosome 3B near markers Xgwm505 and Xgwm615 was 2.6cM, and this QTL was detected repeatedly in different years using different methods and different strains for evaluation.4. The sequences of different copies of TaPDR1 gene in Wangshuibai and Alondra’s were compared and primers were designed according to their SNPs, a SNP marker named SNP-PDR1 was developped. The marker showed polymorphism between Wangshuibai and Alondra’s. However, we failed to map it on the linkage map.

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