Breeding Application For Comprehensive Quality In A Large Germplasm Collection Of Chinese Wheat Landraces

Wheat landraces have good adaptability to local natural conditions and cultivation environment,and have abundant agronomic traits and genomic diversity.With the narrowing genetic basis of modern breeding,wheat landraces have become important germplasm resources.Moreover,Chinese Wheat Landraces are abundant in number and types,and have excellent potential in wheat quality breeding.The quality of wheat is mostly a quantitative trait,which is greatly affected by environmental factors,manifesting as continuous variation and complex genetic basis.Today,with the rapid development of molecular biology,genome-wide association analysis as a new technology has begun to be applied in the field of plants.Compared with the traditional QTL,genome-wide association analysis has the advantages of wide allele coverage and high precision.It can explore more useful gene loci,enrich the genetic basis of modern wheat quality breeding,and provide new gene resources for wheat quality improvement.In this study,272 Chinese wheat landraces were planted in Chongzhou for three consecutive years.Nine quality characters including protein content,starch content,settlement value,falling number,wet gluten,gluten coefficient,stable time,water absorption and valorimeter value were determined and analyzed.Combined with the polymorphic sites on wheat660k chip,the whole genome association analysis of 272 quality traits based on the obtained population structure and genetic relationship was carried out to provide excellent heterotopia points for wheat quality breeding.The main research results are as follows:(1)The quality characters of 272 Chinese wheat landraces in Chongzhou environment for three consecutive years were analyzed.Nine quality characters of three-year wheat landraces have wide variation,the biggest variation coefficient is the stable time,which is53.29%,the smallest is the starch content,which is 4.65%.All quality traits were significantly affected by the year and variety,indicating that genotype and environmental factors had significant effects on the variation of traits.According to the quality classification standard of wheat varieties,the local varieties were classified and screened.According to the comprehensive analysis of each quality,the protein content of local varieties is high but the quality is poor.The strong gluten wheat varieties with high quality potential were found,such as centipede wheat(Changshan,Zhejiang),xiaohongmang,guangtou white shell wheat,wheat(Hezheng,Gansu),Suzhuo Zhuoma and pumang red wheat;the weak gluten wheat varieties,such as Yangmai(Huanggang,Hubei),yuzuiwei wheat and early winter wheat.According to the difference of wheat region of local varieties,the analysis of wheat region difference was carried out.In General,from north to south,the proportion of strong gluten wheat of local varieties decreased,while the difference between the East and the West in the proportion of strong gluten wheat of local varieties was small,the difference between the north and the South was small,but it was mainly concentrated in the East,the distribution of strong gluten wheat was similar to that of strong gluten wheat,while the middle gluten wheat was concentrated in the three wheat regions of the Huang Huai Hai,the middle and lower reaches of the Yangtze River and South China.(2)Using 178803 polymorphic SNP markers with diversity and MAF≥0.05 screened from wheat660k chip,the whole genome association analysis of 272 wheat landraces in China was carried out.A total of 312 SNP markers(P<0.0001)were detected.Except for chromosome 1D,all the other chromosomes were distributed.The total contribution rate of phenotype variation(R~2)of all related loci was 7.60%～23.16%.54 highly significant SNP markers and 14 QTLs were detected in both environments.Among them,the most stable protein content related loci/QTLs were 50(13qtl),which were distributed on chromosomes 1A,2A,1B,3B,3D,4A,5B,6B,7A and 7B.Moreover,the most stable related loci were located on chromosome 3B,mainly in the QTLs of 254.14-273.17 Mb,287.71-295.39 Mb,298.36-301.34 Mb,332.33-337.74 Mb,343.36-353.17 Mb,355.27-358.68 Mb and 365.49-366.95 Mb.One stable correlation site related to starch content was detected at 185.82Mb on chromosome 6A;two stable correlation sites related to settlement value were detected at 101.10Mb and 109.16Mb on chromosome 4D;one stable correlation site related to gluten coefficient was detected at 93.98Mb on chromosome 1A.There were few stable correlation Very significant of falling number,wet gluten,stable time,water absorption and valorimeter value.In addition,SNP loci associated with quality traits of 272 Chinese wheat landraces were predicted and annotated.These candidate genes are mainly related to the synthesis and transformation of nutrients such as amino acids,proteins,fats,sugars,resistance proteins,cytochromes,transporters and protein kinases.