| Maize is one of the world’s top three staple foods,and with the development of society,people’s demand for healthier food has gradually increased,and the mineral element and carotenoid content of maize seeds affect the quality of maize.In this study,170 maize backbone inbred lines were used to analyze the genetic variation of mineral and carotenoid traits in the seeds and to screen for superior germplasm with high mineral and carotenoid contents.The genome-wide association analysis was carried out in combination with 3 million SNP markers covering the whole maize genome,and the genetic basis was initially resolved.The main research findings are as follows:First,the content of five mineral elements(Cd,Cu,Fe,Mn,and Zn)in 170 germplasm grown at two locations in Jiangmen,Guangdong,and Ledong,Hainan was determined based on microwave ablation-inductively coupled plasma mass spectrometry,and it was found that all five mineral elements had abundant genetic variation in maize germplasm resources.the average content of Cd in the two locations was 0.02mg/kg,and the average content of Cu in the two locations was 3.34mg/kg.Cd averaged 3.34mg/kg,Cu averaged 51.13mg/kg,Mn averaged 8.69mg/kg and Zn averaged 21.40mg/kg at both sites,and the correlation coefficients between Fe and Mn and Zn and Mn were found to be significant for all five trait indicators at both sites;by genome-wide association By genome-wide association analysis,a total of 8872 SNP loci were detected to be closely associated with seed mineral element traits in the two environments,of which 7964,398,149,100 and 264 SNP loci were significantly associated with Cd,Cu,Fe,Mn,and Zn element traits,respectively.And 7 loci/intervals were localized to more than 2 traits or 2 environments simultaneously,and 27 colocalized candidate genes were screened in the 100 kb range upstream and downstream of the significant loci.These included the Zm HMA3 gene that has been reported to be involved in Cd element accumulation.Second,In Del primers were designed to validate 30 of these mineral elementsignificant loci based on the results of genome-wide association analysis for localization.The results showed that five polymorphic primer pairs were screened out of the 30 pairs of In Del marker primers,among which the Chr2Cd1 marker regulating Cd content showed phenotypic co-segregation and had greater application value.Thirdly,the carotenoid contents of 170 representative maize germplasm were determined by high-performance liquid chromatography(HPLC),with the distribution ranging from 10.59mg/kg to 122.84mg/kg.The four carotenoid fractions measured had significant correlation coefficients between lutein and zeaxanthin,lutein and β-carotene,and zeaxanthin and β-cryptoxanthin at both locations.By genome-wide association analysis,a total of 1197 significant SNP loci were detected to be closely associated with the traits of interest,12 loci/intervals were localized to two or three traits simultaneously,and 29 co-localized candidate genes were screened in the 100 kb range upstream and downstream of the significant loci.Correlation analysis was also carried out for material elements and carotenoid content,which showed no significant correlation between the two.In this experiment,the genetic variation of 170 good germplasm in seed mineral elements and carotenoid content was analyzed,Screening of 23 excellent germplasm resources with high beneficial and low harmful elements and 68 excellent germplasm resources with carotenoid content >50mg/kg were screened;10069 significant SNP loci were identified,and the In Del primer Chr2Cd1 was developed to predict the seed Cd content more accurately.This study provides an important reference for the discovery of excellent maize germplasm resources and variety improvement. |
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