Genome-wide Association Study Of Traits About Major Nutritional Quality In Maize

Maize is an important feed resources for the development of livestock breeding and its nutritional quality is very important to animal husbandry.Genetic improvement is one of the effective ways to improve the quality of maize,and it is helpful to study the genetic basis of maize nutrition quality.In this study,the near-infrared spectroscopy(NIRS)technique was used to determine the main nutritional quality of 338 maize inbred lines and provided available germplasm resources for the high yield,high quality maize varieties.Genome level scanning was performed using a chip containing 56110 SNP marks to obtain genotype for 338 inbred lines.Based on the phenotype and genotype,the genome-wide association analysis was carried out,and the genes that controlled each nutritional quality trait were extracted and analyzed from the molecular level to the main quality traits of maize,which provided a theoretical basis for the genetic improvement of quality traits.The main results of this study were as follows:1.Silage quality of 338 maize inbreed lines such as ADF(Acid Detergent Fiber),NDF(Neutral Detergent Fiber),IVDMD(In Vitro Dry Matter Digestibility),CP(Crude Protein)and other major nutritional quality traits were measured and calculated the whole content of each nutrient quality traits,combining with the national quality of silage corn classification standard and 31 materials met the national secondary standard,which could be used as an excellent germplasm resource for silage maize breeding in the future.2.The 44,990 high quality SNP markers with polymorphism were selected,and the average distance between adjacent markers was 46 Kb.The results of the group structure analysis showed that 338 maize inbred lines could be divided into three subgroups:Tropical group,including 114 inbred lines,and the representative material was S37;The NSS group,consisting of 53 inbred lines,represented the material as Qi319;The SS group,comprising 127 inbred lines,represented the material as Ye478 and B73.3.The results of single factor variance analysis of 3 sub-populations showed that there were significant differences in the content of kernel oil,protein and starch in tropical maize and SS population maize,and there was no significant difference in thecontent of glutamate and lysine,and the tropical population was higher in oil and protein content than SS population,and lower in starch content than SS population.In straw nutritional quality traits except kernel,NDF content of bract in tropical population was significantly higher than SS population,and the IVDMD content of leaf,CP and IVDMD content of bract in tropical population was significantly lower than SS population.In terms of the whole silage quality,the NDF content of tropical population was significantly higher than SS population,and there was no significant difference in the content of ADF,CP and IVDMD.4.Genome-wide association study of the kernel oil content was carried out to obtain2 significant SNP,PZE-105182097 and SYN7798,which respectively located on chromosome 5 and chromosome 8,and the physical locations were 216645682 bp and14593507bp.One candidate gene GRMZM2G481843 was screened.5.Genome-wide association study of kernel starch content was carried out to obtain5 significantly related SNP,ZM006949-0697,SYN26622,SYN32247 and SYN32244 were all located in chromosome 5,and the physical locations were 65224253 bp,65224366bp,65417455 bp and 65418915 bp.PZE-108091532 was located on chromosome 8,and the physical location was 148676361 bp.Three candidate genes were screened,they were GRMZM2G112805,GRMZM2G130586,GRMZM2G132060,respectively.6.Genome-wide association study of ADF content obtained 4 significant SNP,pz-102079140,physical location was 61856982 bp and located on chromosome 2;PZE-105062148,physical location was 61353927 bp and located on chromosome 5;Pz-108053479 and SYN23212 were all located on chromosome 8,and the physical locations were 95301909 bp,164430850bp.Two candidate genes,GRMZM2G329325 and GRMZM2G093826 were screened.7.Genome-wide association study of NDF content was conducted to obtain 10 SNP with significant associations,pz-101117214,located on chromosome 1,and the physical location was 141682056 bp.SYN7494,SYN7499,SYN7496,pz-102076751 and pz-102079140 were located on chromosome 2,the physical locations were 209301452 bp,209340274bp,209351001 bp,58595912bp and 61856982 bp.PZE-108098094,PZE-108098097 and PZE-108098148 were located on chromosome 8,physical locations were 154148045 bp,154150646bp and 154266661 bp.SYN22969 was located on chromosome 10 with a physical location of 132526605 bp.7 candidate genes were screened,they were GRMZM2G115817,GRMZM2G146292,GRMZM2G146416,GRMZM2G073054,GRMZM2G093826,GRMZM2G023667 and GRMZM2G468661,respectively.8.Genome-wide association study of CP content was carried out to obtain three SNP with significant associations.pz-103044113,PUT-163a-18168669-1322 and pz-110037264 were located on the chromosome 3,6,10,and the physical locations were43524890 bp,111031131bp and 71105475 bp,respectively.One candidate gene was screened.9.Genome-wide association study of IVDMD content was conducted to obtain three SNP with significant correlation.PZA03659.3 and SYN36155 were located on chromosome 2,and the physical locations were 176727598 bp and 176871550 bp.PZE-110065138 was located on chromosome 10,and the physical location was120793997 bp.Two candidate genes were screened,they were GRMZM2G300955 and GRMZM2G167245,respectively.