Genome-wide Association Analysis Of Nutritional Quality Traits In Triticale Grains

Objective: The grain quality of Triticale is the main index to determine its end use and evaluate the quality of varieties.Grain quality is a complex quantitative trait.Revealing its genetic basis and exploring its molecular markers are important basis for improving grain quality of triticale.This study intends to explore the SNP loci and candidate genes associated with grain quality traits of Triticale through genome-wide association analysis,and to provide a theoretical basis for revealing its genetic mechanism,molecular marker assisted selection and quality improvement.Method: In this study,300 triticale Germplasm from 20 countries in 6 continents were used as natural populations to systematically determine the four important grain quality traits of crude starch content(GSC),protein content(GPC),straight(AC)and amylopectin content(APC)of mature grains harvested in two years.At the same time,300 triticale germplasm were sequenced by SLAF SEQ technology,and the genome-wide association analysis was carried out by using mixed linear model(LMM).The significant SNP loci of Triticale grain quality traits were excavated,and their significant SNPs were annotated.Results:1、The four grain quality traits of 300 triticale germplasms in two years showed extensive variation.The largest coefficient of variation was the amylose content,which was 20.72%,and the smallest was the crude starch content,which was 6.59%.The differences between genotypes,years,and the interaction between genotypes and years of quality traits all reached significant levels(P<0.001).The heritability of the four grain quality traits was all high(more than 70%).2、Through SLAF-seq sequencing technology,a total of 2149.59 Mb reads data were obtained,of which874 612 SLAF tags were obtained when the AB genome was used as a reference,of which 637 212 were polymorphic SLAF tags;459 288 were obtained when the R genome was used as a reference SLAF tags,of which there are 277 225 polymorphic SLAF tags.3、A total of 78 SNP loci closely related to 4 grain quality traits were identified,of which 8 loci closely related to GSC were distributed on R3 chromosome;There are 37 loci closely related to GPC,which are distributed on chromosomes 1a,1b,2a,5b and 6B;There are 26 loci closely related to AC,which are distributed on chromosomes 2a,5A,7b and R3;Among them,there are 7 loci closely related to APC,which are distributed on chromosomes 1b,6a,R5 and R6.4、A total of 27 candidate genes related to grain quality were detected,including 4 candidate genes for crude starch content,9 candidate genes for protein content,6 candidate genes for amylose content and 8candidate genes for amylopectin content.Scwn3r01g107700 encodes nitrate reductase 1.It can directly regulate the reduction of nitric acid,and to regulate nitrogen metabolism and then affect photosynthetic carbon metabolism;Sc WN6R01G330500.1.It encodes F-box protein genes and plays the role of protein degradation in plants through ubiquitin protease pathway;Tritd7bv1g168170 encodes ubiquitin carboxyl terminal hydrolase,which participates in ubiquitin proteasome pathway,targets the degradation of macromolecular proteins,and then realizes the activation and transfer of nitrogen groups;Tritd6av1g209030 encodes protein kinases such as serine or threonine.Conclusion: 78 stable loci associated with triticale grain quality traits were detected,and 27 candidate genes associated with triticale grain quality traits were screened.