| Wheat Fusarium head blight（FHB）is a global fungal disease caused by Fusarium spp,in recent years,the incidence of the disease has become increasingly serious and the scope of occurrence has been expanding.The occurrence of Fusarium head blight not only resulted in the decline of wheat yield and quality,but also accumulated a variety of mycotoxins such as Deoxynivalenol（DON）,Nivalenol（NIV）and Zearalenone（ZEN）in grain.Serious threat to China’s food security and human and animal health.In this study,a natural population of 129 wheat cultivars was used to investigate the percentage of infected spikes and disease index in the field.The contents of DON,NIV and ZEN mycotoxins in wheat grains were measured by Ultra Performance Liquid Chromatography to explore the relationship between resistance to fusarium head blight and accumulation of antitoxin.Genome-wide association analysis of disease index and toxin content was carried out based on the 90K SNP chip in wheat,and the important loci regulating the resistance traits of fusarium head blight were identified and related candidate genes were screened.The main results are as follows:1.The results of toxin content determination of 129 wheat materials showed that the detection rates of DON,NIV and ZEN were 100%,97.69%and 82.95%,respectively,and the overstandard rates were 18.60%,15.50%and 10%,respectively.Based on disease index and three toxin contents,34 excellent resistant germplasm were screened(disease index<30%,DON content≤1 000μg·kg-1,NIV content≤500μg·kg-1,ZEN content≤60μg·kg-1).Among them,yangmai 14,Yang12-145,Niavt14 and DP36 showed low disease index and toxin content in three years.2.Correlation analysis of percentage of infected spikes,disease index,DON,NIV and ZEN contents showed that the percentage of infected spikes and disease index were significantly positively correlated with DON and NIV content（correlation coefficients were 0.424,0.462,0.431 and 0.495,respectively）.There was no significant correlation between percentage of infected spikes,disease index,DON content and ZEN content（correlation coefficients were 0.169,0.146,0.158,respectively）.The relationship between fusarium head blight incidence and toxin accumulation may be inconsistent due to different genotypes of wheat,and non-genetic factors may also affect the determination of toxin content.Therefore,resistance to fusarium head blight cannot be measured by only one index.3.Disease index,DON and NIV content of 91 wheat materials in two years were analyzed by GWAS using the wheat 90K SNP chip combined with MLM and GLM models.A total of 128 significant SNP markers（P≤0.001）were associated,distributed on19 chromosomes except 1D and 4D.Eleven stable loci were detected in two or more environments.There were only 6 loci associated with toxin stability,which were located on chromosome 1A,4A,6A,6B and 6D respectively,and could explain 11.96%～30.50%of phenotypic variation.Four loci were stably associated with toxin and disease index,which were located on chromosome 2A,2B,5B and 5D respectively,and could explain12.21%～34.11%of phenotypic variation.QFhb.ahau-2A can be detected in all three traits and can explain 18.90%-20.94%of phenotypic variation,which is worth further study.4.A total of 15 candidate genes related to fusarium head blight resistance were screened in stable QTL segments based on the Chinese Spring reference genome information and functional annotations of related genes.It provides reference for marker-assisted selection and gene cloning. |
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