Mapping For Major QTL Conferring Resistance To Orange Wheat Blossom Midge In Wheat And Its Source Analysis Among Wheat Varieties

Orange wheat blossom midge(Sitodiplosis mosellana Gehin)is an economically important pest insect that affects wheat yield worldwide.Breeding resistant cultivars is the most economical and effective measure to control midge.The emergence of molecular marker assisted selection(MAS)breeding method can greatly improve the breeding efficiency of resistant wheat varieties and it was beneficial to realize the convergence and simultaneous improvement of the OWBM resistance and other excellent agronomic traits of wheat varieties.At present,the foreign researches of midge mainly focus on the study of spring wheat resistance genes.In domestic winter wheat varieties,our group has found some midge-resistant related sites.However,limited by marker number and marker density,the linkage markers are still very restricted in the application of breeding of midge-resistant varieties.So,new midge-resistant gene resources and effective function markers should be discovered and developeded.In this study,two recombinant inbred populations were used as material to construct the genetic map by using selective population and entire population combined with SNP and SSR markers to map the major QTLs related to midge resistance and to screen the molecular markers closely linked to midge resistant genes for molecular breeding.According to the pedigree of midge-resistant varieties,the source of midge-resistant chromosome sections can be found.The main research results are as follows:1.Two different selective populations were used to QTL mapping analysis for the midge resistance gene of wheat.Seven QTL related to midge resistance were detected.In two populations,the effect values of the major QTL locus on chromosome 4A was high and stable,and the physical interval on chromosome 4A overlapped.Through comparative analysis,the midge-resistant major QTL was located between the SNP markers AX-109543456 and AX-108942696 on the long arms of chromosome 4A,and the corresponding physical interval was 4.9Mb(703434395-708327301 bp).According to the gene functional annotation,nine genes in QTL interval may be related to OWBM resistance.2.Entire population was also used to map the QTL related to midge resistance and the major QTL on chromosome 4A can be detected.This major QTL was located in the 2.8Mb(704444188-707248000bp)interval between EST and SSR markers E1-2 and hs270.The physical interval was included in the 4.9Mb interval of selective population.Therefore,both the selective population and the entire population can be used to map the major QTL,and the cost of selective population is low.3.Through pedigree and genetic analysis of sixty-five varieties,it was found that the midge resistance genes of resistant parents Henong 215 and Jimai 24 were similar,and this resistance genes were from Xinong 6028.In addition,Xinong 6028,Nanda 2419 and Lovrin 10 contained similar resistance loci in the QTL interval,the resistance loci within the physical interval(704444188bp-707831859bp)has strong transfer ability.In this study,two selective populations and one entire population were used to map the QTL related to midge resistance.Seven and six QTL were detected in selective populations and entire population,respectively,and the major QTL was mapped to a 4.9Mb(703434395-708327301bp)interval on the long arms of chromosome 4A.According to the gene functional annotation analysis,nine genes in the QTL interval may be related to OWBM resistance.Through pedigree analysis,it was found that the midge resistance locus of two resistant parents Henong 215 and Jimai 24 were similar,and the resistance locus were probably from Xinong 6028.