| Fusarium head blight(FHB,scab)is a global wheat disease which affects the safety of wheat production.The resistance is controlled by multiple genes/QTL.Pyramiding multiple stable QTL with large effects under different environments or genetic backgrounds is an effective strategy to improve the germplasm resistance to FHB.Wheat resistance to FHB spread within a spike(Type Ⅱ)and mycotoxin accumulation in infected grain(Type Ⅲ)are the two most important types of resistance.To date,hundreds of the QTL have been reported,but only a few QTL underlying the two traits have been utilized in breeding programs because most of them showed minor effects and may not be repeatable in different genetic backgrounds.However,most of the QTL are poor in stability and can not be well utilized.Genome-wide association studies(GWAS)is a good method to map the QTL of complex quantitative traits.The genome-wide scanning based on high-density SNP array has become an efficient method to identify new resistance sources and to excavate new loci of resistance to wheat scab.In this study,we conducted a meta-analysis of the QTL for these two resistance types.The meta-analysis and the integration of related information were optimized and improved in the following aspects when compared with the previous QTL meta-analysis studies:1)up-to-date QTL retrieved from 113 published literatures available before January 2020 were included;2)a panel of 118 consensus genetic map-based MQTL(gMQTL)were identified from a total of 625 original QTL via Biomercator V4.2.3,and these gMQTL were then projected to the reference sequence of Chinese Spring(IWGSC RefSeq V1.1),generating the reference sequence-based MQTL(sMQTL),which were further refined to 77 highly confident MQTL(hcMQTL);3)copy number of the SNP markers from the 660K and the 820K SNP arrays and that of SSR markers were analyzed,and both single-copy SNP markers and the SSR markers were intergrated with the hcMQTL intervals,within which the single-copy SNP markers were further transformed into CAPs/dCAPS markers;4)the public transcriptomic and proteomic data related to wheat responses to FHB from both our laboratory and colleagues were re-analyzed and integrated with hcMQTL intervals,within which 17 genes evidenced by both transcriptomic and proteomic were identified,which could be the candidate genes for further work.The hcMQTL identified in this study can be pyramided,via locus-specific markers assisted selection,into wheat to improve FHB resistance,which would be also convenient for paralleled comparisons between independent mapping results.Type Ⅱ resistance to FHB in a panel of 261 wheat accessions was evaluated for three consecutive years from 2017 to 2019,and Type Ⅲ resistance was determined in 2019.The results showed that Type Ⅱ and Type Ⅲ resistances had high heritability.After screening,48 accessions showing both low proportion of symptomatic spikelets(PSS)and low DON content in grains were identified to provide excellent parental lines for genetic improvement of wheat scab resistance.In addition,55K SNP array were used for genotyping the panel,and association analysis was performed.Twenty SNPs were significantly associated with Type Ⅱ resistance and eight SNPs with Type Ⅲ resistance using FarmCPU model.Among them,one locus on chromosome 7B associated with Type Ⅱ resistance were reproducible in three environments with high heritability and one locus on chromosome 4A were reproducible in two of the three environments.Finally,the SNPs significantly associated with Type Ⅱ and Type Ⅲ resistances were integrated with the hcMQTL intervals.The locus on chromosome 7B was then associated with both transcriptomic and proteomic data,which provided a basis for the development of diagnostic markers,gene cloning,and improvement of FHB resistance using pyramiding breeding strategy. |
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