| The main goals of maize breeding are high yield,stable yield and high quality.High yield and stable yield have been realized basically.The study of maize kernel quality has been paid more and more attention.For maize that uses heterosis,hybrids are used in production.Based on the natural population,RIL,DH,F2,BC and other traditional mapping populations for association analysis or linkage analysis,the mapping results are an indirect reflection of F1 genetic research.In order to directly study the loci or regions of F1 controlling maize kernel quality-related traits,the results of traditional mapping populations were supplemented.In this study,248 inbred lines with rich genetic diversity were used to construct natural population.100 inbred lines were screened from natural population as the female parent,and 4 different backgroung maize inbred lines Mo17,E28,Chang7-2 and Zheng58 are test parents.According to NCII,400 hybrids(100 females × 4 males)were constructed.We constructed 4 test cross populations,which are Mo17 test crosspopulation,E28 test cross population,Chang7-2 test cross population,Zheng58 test cross population.Every test population has 100 hybrids.Starch content,protein content,oil content,and lysine content of four natural populations and four test cross populations in multiple environments,combined with sequencing-based high-throughput SNP markers,kernel quality traits of each population were performed by genome-wide association analysis.The results of the study were performed as follows:1.The starch content,protein content,oil content and lysine content of the natural population and the four tested crosses showed a large degree of variation and a high degree of dispersion.The results showed that there were phenotypic diversity in kernel quality-related traits.The absolute values of the skewness and kurtosis of each trait in each environment are substantially less than 1,which indicated that the results of these traits conform to the normal distribution.2.The kernel quality traits were significantly different in the four test cross populations.The starch content of Zheng58 test cross population was significantly higher than that of other populations.The protein content of E28 test cross population and Chang7-2 test cross population was significantly higher than other populations;the oil content of E28 test cross population was significantly higher than other populations;Mo17 test cross population Lysine content is significantly higherr than other populations.3.The method of best linear unbiased prediction was used to deal with the phenotypic data of different environments of kernel quality traits in natural population and 4 test cross populations.The genome-wide association analysis of the starch content,protein content,oil content and lysine content in the natural population and the four test populations was performed by Farm CPU.The natural population were detected 7,4,11,and 4 SNP loci associated starch content,protein content,oil content,and lysine content,respectively.Mo17 test cross population were detected 8,7,9,and 10 SNP loci associated starch content,protein content,oil content,and lysine content,respectively.E28 test cross population were detected 12,4,4,and 7 SNP loci associated starch content,protein content,oil content,and lysine content,respectively.Chang7-2 test cross population was detected 7,6,5,and 9 SNP loci associated starch content,protein content,oil content,and lysine content,respectively.Zheng58 test cross population were detected 11,13,10,12 SNP loci associated starch content,protein content,oil content,and lysine content,respectively.4.Co-sites between different populations of the natural population and the four test cross populations in the same kernel quality traits were screened.There are no co-sites between the natural population and the four test cross populations.11 co-sites were detected in the same kernel quality trait of four different test cross populations.Among them,4 co-sites were detected in the starch content,no co-sites were detected in the protein content,1 co-sites was detected in the oil content,and 6 co-sites were detected in the lysine content.5.These 11 co-sites were donated 24 candidate genes associated kernel quality trraits.Among them,9 candidate genes are related to starch content,4 candidate genes are related to oil content,and 11 candidate genes are related to lysine content.In this study,natural populations and four test cross populations with different genetic background were used to locate genetic loci for controlling kernel quality traits in F1.It is a useful supplement to the results of association analysis or linkage analysis based on natural population,RIL,DH,F2,BC and other traditional maize mapping populations.It provided a reference for further improvement of maize kernel quality. |
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