| Starch is the main component of wheat grain and determines the quality of wheat processing quality.In this study,150 wheat cultivars(lines)in the south of Huanghuai region were used to identify starch traits under five environments,and genome-wide association studies(GWAS)using the wheat 35K SNP genotyping assay were carried out for those traits.The main results are as follows:1.A total of 35,143 SNP markers were found in 150 wheat cultivars(lines)by the 35K SNP genotyping assay,and 9552 high-quality stable polymorphic markers were obtained after screening.Group structure and principal component analysis divided the materials into two subgroups.The polymorphism information content(PIC)ranged from 0.0950 to 0.5000 and the order of average PIC in three genomes was A(0.3317)>B(0.3240)>D(0.3100).Linkage disequilibrium analysis found that A,B,D and the LD attenuation distances of the whole genome were 4.7,8,11,and 6 Mb,respectively.2.Total starch content had a very significant positive correlation with amylopectin content and a very significant negative correlation with hardness index,protein content and wet gluten content.Amylose content had a negative correlation with amylopectin content,hardness index and protein content,and a significant negative correlation with wet gluten content.Amylopectin content had a significant negative correlation with protein content and wet gluten content.Very significant positive correlation was found between protein content and wet gluten content with the larger related coefficient of 0.981.3.A total of 545 related markers were detected in wheat starch traits,including 197 markers for total starch content,214 markers for amylose content and 134 markers for amylopectin content.Nine related markers were stably detected in two or more environments.Among them,three stable markers were related to total starch content and located on 3D,6B and 7B,respectively,and their contribution rates of phenotypic variation(R2)ranged from 6.30%to 12.00%.Six stable markers were related to amylose content and located on 5B,5D,6A,6B,6B and 6D,respectively.AX-95258242 located on 5B was detected in three environments and its R2 ranged from 5.10%to 9.00%.All the markers related to amylopectin content were detected only in single environment.AX-94414203-A with the largest effect value increased the starch content 1.72%,AX-95100615-C increased it by 1.40%,AX-94494277-A decrease it by 1.51%,and the occupancy frequencies in the population were 90.60%,11.03%and 87.60%,respectively.AX-94391044-A,AX-95159175-A,AX-95209203-A,AX-94781187-A,X-94685800-A and AX-95258242-A reduced amylose content,and their occupancy frequencies were 91.78%,89.19%,89.19%,85.45%,69.13%and 69.59%,respectively.4.A total of 675 related markers were detected in wheat protein content,wet gluten content and hardness index,including 163 protein content markers,228 wet gluten content markers and 284 hardness index markers.One hundred and forty-seven SNP markers were stably detected in two or more environments.Forty-two stable markers related to protein content were located on fifteen chromosomes,their R2 ranged from 5.63%to 17.18%,and among them,AX-94843838 located on 5B was detected in four environments.Thirty-six stable markers related to wet gluten content were located on thirteen chromosomes,their R2 ranged from 5.64%to 14.61%,and AX-94780647 located on 1D was detected in four environments.Sixty-nine stable markers related to hardness were located on 16 chromosomes,their R2 ranged from 5.57%to 34.09%,and AX-94813152,AX-94795975,AX-95631542,AX-94922331,AX-94991433 and AX-94716438 were detected in five environments.A total of One hundred and forty-seven dominant allelic variants were found in three quality traits.AX-94414203-A on 6B with the greatest decrease effect reduced protein content by 1.61%,AX-94690816-A on 5A with the largest increase effect increased protein content by 1.10%,and their occupancy frequencies were 90.60%and 6.00%,respectively.AX-94780647-A on 1D and AX-94414203-A on 6B reduced wet gluten content by 3.36%and 3.66%,respectively,AX-94690816-A on 5A increased by 2.46%,and their occupancy frequencies were 93.33%,90.60%and 5.98%.AX-95112961-A on 5A with the largest effect increased hardness index by 21.34,AX-94923627-G on 5D decreased by 19.33,and their occupancy frequencies were 94.56%and 5.17%,respectively.5.A total of 115 candidate genes were found,and among them,fifteen for two or more traits.TraesCS6B02G136400 was a common candidate gene for starch content,protein content and wet gluten content,and the others were candidate genes for protein content or wet gluten content.Except for TraesCS4A02G343900 and TraesCS5D02G339400,the other thirteen candidate genes had gene or protein function annotations,and their functions need further study.There were six same candidate genes in two different SNP sites.The candidate gene of protein content for AX-94960802 and AX-95250370 on 2A was TraesCS2A02G080700,and that of wet gluten content for AX-94795268 and AX-94861346 on 5D was TraesCS5D02G544700.The others were the candidate genes of hardness index on 1B,including TraesCS1B02G240400 for AX-94750591 and AX-94957845,TraesCS1D02G226200 for AX-95000586 and AX-95137260,TraesCS2D02G391000 for AX-94749848 and AX-94637067,and TraesCS5B02G384200 for AX-94417031 and AX-95629800. |
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