Genome-wide Association Analysis And Linkage Analysis Of Wheat Kenel Related Traits And The Exploring Of Important Gene Loci

Kernel related traits is the major objective of wheat breed improvement.There are many factors influencing kernel related traits.According to the actual observation in the field and previous research results,kernel related traits of kernel size,leaf traits(flag leaf traits and leaf senescence)were selected to study the genetic regulation of thousand kernel weight,flag leaf width,flag leaf length,flag leaf area,length-width ratio of flag leaf and leaf premature senescence.It is expected to provide some useful molecular research for wheat yield traits and increase wheat yield.The results are as follows:1.According to genome-wide association analysis with 90 K chip,4,417 SNPs for kernel length,3,172 SNPs for thousand kernel weight and 650 significant SNPs for grain width were identified in 14 environments over multiple years.The most SNPs associated with kernel length and thousand kernel weight were obviously distributed on chromosome 7B.Haplotype analysis indicated that the homologous gene Os GW8 of rice was contained in a block section.The Ta GW8-B1 gene contained 4826 bp was cloned in hexaploid wheat.2.Ta GW8-B1 a and Ta GW8-B1 b the allele of Ta GW8-B1 gene were found in Chinese wheat cultivars.The molecular marker Ta GW8-7B was developed to identify the Ta GW8-B1 a and Ta GW8-B1 b alleles.The correlation analysis between agronomic traits and Ta GW8-B1 gene in 365 cultivars over three years showed that cultivars with Ta GW8-B1 a allele had significantly wider kernel width and significantly higher kernel number per spike than the cultivars with Ta GW8-B1 b allele.The cultivars possessed Ta GW8-B1 a allele produced higher yield from yield surveys of 246 recently cultivars or advanced lines in 14 environments.Among Chinese wheat cultivars,the Ta GW8-B1 a allele is dominant with accounting for more than 85%.However,the Ta GW8-B1 b allele has a trend of slow increase.3.The relative expression level of Ta GW8-B1 gene was investigated in seed development stage and mature seeds after harvest.The result showed that the expression110 of Ta GW8-B1 gene increased gradually 28 days after flowering as well as in the middleand late stage of grain filling.The relative expression of Ta GW8-B1 a was higher than that of Ta GW8-B1 b allele and the expression of Ta GW8-B1 gene increased sharply at 42 days after flowering.Meanwhile,the relative expression of Ta GW8-B1 a allele was significantly higher than that of Ta GW8-B1 b allele in mature seeds.These results indicated that Ta GW8-B1 gene was positively correlated with kernel width and thousand kernel weight.4.Through genome-wide association analysis of 163 representative wheat cultivars in Yellow and Huai wheat region 181 SNPs for flag leaf length,99 SNPs for flag leaf width,123 SNPs for flag leaf area and 215 SNPs for length-width ratio of flag leaf were found in 9 environments.IACX10100 locus was found in all 7 investigated environments and was associated with flag leaf length to width ratio,flag leaf length ratio and flag leaf area.Among the 16 SNPs loci related to flag leaf length to width ratio,A/A/T/G/C/G/G/G/ A/A/T/C/T/A/A/Cgenotype combination phenotypic values is 11.27,while the C/A/C/A/T/T/A/A/G/G/C/G/T/A/C/C composite phenotypic value is 23.67.3QTLs for flag leaf length,8 QTLs for flag leaf width,4 QTLs for flag leaf area and 8QTLs for length-width ratio of flag leaf were detected in PC population.Qflw-5A ?Qlwr-5A.1 and Qfla-5A were found between the same flanking markers and all were associated with flag leaf width,flag leaf length to width ratio,flag leaf area.Moreover,some significant SNPs related to flag leaf traits by genome-wide association analysis were located in the interval of QTLS for flag leaf traits.Those result provide useful information for further analysis of flag-leaf related traits.5.The cultivar Xinmai 26 and Zhoumai 22 cross to form RIL population(XZ population).The genes related to leaf premature senescence scale 2 were located on chromosome 5B ranged from 399 Mb to 411 Mb in segregation lines XZ-42.Transcriptome analysis of leaf premature senescence strains and normal strains in XZ-42 lines indicated that differential expression genes are mainly involved in circadian rhythm,plant hormone response and signal transduction,defense response and other biological pathways.There are 12 differentially expressed genes on chromosome 5B between 363 Mb and 410 Mb.Traes CS5B02G219500 and Traes CS5B02G219600 genes are associated with auxin induction proteins and Traes CS5B02G224100 is a WRKY homologous gene.The metabolites analysis of normal and premature senescence strains in XZ-42 lines showed that plant hormones indole-carboxylic acids,salicylic acids and phenolamides related to plant defense were found.These results showed that prematuresenescence is a combination of multiple regulatory processes,which may be related to auxin,salicylic acid and biological defense.According to the analysis of kernel size,flag leaf size,leaf senescence those traits related to yield,the superior Ta GW8-B1 a allele for yield,some important SNPs loci and QTLs loci associated with flag leaf size were found.The differential expression genes and metabolites related to senescence were explored.It provided useful molecular markers for breeding,important genetic loci for improving wheat plant type.At the same time,it also provided reference information for analyzing the regulation pathway of leaf senescence and cloning related genes.