SNP-based Association Analysis For Grain Filling Related Traits And Grain Weight In Durum Wheat

Wheat is the most important subsistence crop in the world,with more than 40%of the population taking wheat as their staple food.Wheat mainly includes common wheat(Triticum aestivum,AABBDD,2n=42)and durum wheat(Triticum durum,AABB,2n=28).The area of durum wheat planted is relatively small,accounting for about 10%of the world’s total wheat planting area.Compared with common wheat,durum wheat has the characteristics of better quality,stronger adaptability and rich genetic variation in many traits.It is an important secondary gene source for genetic improvement of common wheat.Grain filling is a key and complicated dynamic physiological process affecting the final yield formation of wheat,which determines the final grain shape,grain weight,plumpness index and other commercial properties.Studying the grain filling characteristics and grain weight genetic characteristics of different durum wheat germplasm is of great significance to excavate excellent durum wheat germplasm resources,enrich the genetic basis of wheat genetic improvement,to enhance wheat yield and quality potential.In this study,a natural population consisting of 150 durum wheat from 41 countries and regions was used as research material,and 10 traits such as grain filling characteristics and grain weight were observed and measured for three consecutive years.The association analysis of the 10 investigated traits 1366 single nucleotide polymorphisms(SNP)markers based on EST sequence was carried out using the mixed linear model(MLM).The main results of the study were as follows:1.Phenotypic analysis of grain filling characteristics and thousand kernel weight in durum wheat:the 10 phenotypic traits(GFR1,GFR2,GFR3,GFR4,GFR5,GFR6,Rmean,Rmax,T,TGW)investigated in this study have rich genetic variation,of which the highest coefficient of variation was the filling rate in the sixth stage.The phenotypic values of all traits showed typical quantitative traits.All of the 10 related traits had high heritability(H~2>77%),of which thousand grain weight had the highest heritability(H~2=93.16%).The correlation analysis showed significant correlation between most of the agronomic traits,thousand grain weight showed extremely significant positive correlation with the other nine grain filling traits,and the duration of grain filling showed extremely significant negative correlation with average grain filling rate and maximum grain filling rate.2.Association analysis of grain filling traits and thousand grain weight in durum wheat:a total of 128 significant association results were detected in 10 agronomic traits investigated for three consecutive years(P<0.01).The number of SNP markers associated with each traits varied from 1 to 22,with the contribution to phenotypic variation ranging from 4.63%to 59.44%.A total of 75 SNP markers were detected at six grain filling rates.The three grain filling parameters of average grain filling rate,maximum grain filling rate and the duration of grain filling were associated with 38 SNP markers,and the associated SNP markers were mainly distributed on chromosomes 3A and 4B.There are 15 SNP markers significantly associated with thousand grain weight,which were distributed on chromosomes 1A,1B,3A,3B,5A,5B,6B,7A,7B,with the most markers on chromosomes 7A and 7B.All SNP markers with significant correlation of investigated traits in this study were mainly located on chromosomes 1A,2A,3A,4B,7A and 7B,forming QTL clusters in specific chromosomes regions of the wheat genome.