Utilization Of A High-Density Genetic Map For Mapping Of Quantitative Trait Loci For Pre-Harvest Sprouting Resistance Of Wheat And Important Quality Traits

During the wax-ripening stage,wheat is vulnerable to the disaster of Pre-harvest sprouting(PHS),and the quality of sprouting wheat are decreased,which caused significant economic loss for people.The Flour yield,Hardness index,Water content,Falling number,Grain protein content,and Ash are important processing or nutritional quality traits of wheat,to detection and analysis of the genes that regulate PHS and those important quality traits,then exploring the genetic mechanism of the corresponding traits will lay a great foundation for molecular breeding and creating wheat cultivar that has the resistance to PHS as well as high-quality.In this study,the RIL population containing 371 wheat lines constructed from wheat cultivar Chuang-Nong 18 and T1208,combined with a high-density genetic linkage map with wheat 55 K SNP array to identify and analyze the QTL about the above traits。The main results from this study are as follows:1.The PHS traits was assessed by whole spike germination method in the field and indoor forfour environments.Wheatsix important wheat quality traits,including Flour yield,Hardness index,Water content,Falling number,Grain protein content,and Ash were assessed in three environments by national standard method and near infrared spectrum analysis technology.The phenotypic values showed a transgressive segregation phenomenon of all traits in the RIL population,the lines with excellent trait phenotype values could as some important germplasm resources for PHS resistance and wheat high-quality breeding.2.The dormancy traits was assumed through wheat seed germination experiment,the result showed that there was not significant correlation(P<0.01)between Spike germination rate traits and Germination index,the seed dormancy could not be the major factor affecting PHS for ours wheat material.3.A total of 19 QTLs of PHS were detected through ICIM-BIP analysis,including one major QTL,QPHS.sicau-2B.3,which explained a phenotypic variation rate up to14.09%.The PHS trait was greatly affected by environmental factors and was detected by gene-environmental interaction analysis,too.A micro effect,stable QTL loci,QPHS.sicau-5D.2,was also identified in two environments.Moreover,the epistatic analysis revealed that the PHS traits were affected by the interaction between the additive QTL and the random loci.4.The difference significance analysis of the phenotypic value between wheat grain Hardness and the Falling number obtained from NIR spectral analysis and traditional methods showed that there were significant differences of Falling number,and the grain Hardness phenotype values measured by different methods have a close correlation(r=0.87,P<0.01).Then we corrected the grain hardness obtained by near infrared analysis,and found that the corrected value still could not be used for genetic mapping,so we thought that near-infrared analysis could not be suitable for assessing complex secondary-processing quality traits,such as the Falling number,and was more suitable for the primary processing quality of wheat.5.A total of 61 QTLs of wheat with important quality traits(Flour yield,Hardness index,Water content,Falling number,Grain protein content,and Ash)were detected by the ICIM-BIP method,including four major QTLs about Falling number,two major QTLs about Flour yield,two major QTLs about Water content and Grain protein content,one major QTLs about Ash content;one stable QTLs about Falling number and Ash for two environments,respectively.There was one stable and major QTL loci of wheat grain Hardness in three environments,QHI.sicau-5D,which explained a phenotypic variation rate up to 15.30%,further analysis suggested that there may be gene Puroindoline in the interval of this loci.The multi-environmental analysis showed that the phenotypic variation explained was low in any of the above quality traits from environmental factors.Epistatic QTL analysis of those quality traits showed that only interactions from random loci have indirect effects on the phenotypic value.6.All major,as well as stable QTLs,tended to be distributed in the same QTL clusters for wheat important quality traits,a total of 14 QTL clusters were detected,it would promote the pyramiding breeding of multi-gene and multi-trait for wheat.This study could lay a great foundation for fine mapping and map-based cloning of genes that controlling those above traits,accelerating marker-assisted breeding process about PHS resistance and high-quality wheat cultivar.