Limits...
Confirmation and Fine Mapping of a Major QTL for Aflatoxin Resistance in Maize Using a Combination of Linkage and Association Mapping

View Article: PubMed Central - PubMed

ABSTRACT

Maize grain contamination with aflatoxin from Aspergillusflavus (A. flavus) is a serious health hazard to animals and humans. To map the quantitative trait loci (QTLs) associated with resistance to A. flavus, we employed a powerful approach that differs from previous methods in one important way: it combines the advantages of the genome-wide association analysis (GWAS) and traditional linkage mapping analysis. Linkage mapping was performed using 228 recombinant inbred lines (RILs), and a highly significant QTL that affected aflatoxin accumulation, qAA8, was mapped. This QTL spanned approximately 7 centi-Morgan (cM) on chromosome 8. The confidence interval was too large for positional cloning of the causal gene. To refine this QTL, GWAS was performed with 558,629 single nucleotide polymorphisms (SNPs) in an association population comprising 437 maize inbred lines. Twenty-five significantly associated SNPs were identified, most of which co-localised with qAA8 and explained 6.7% to 26.8% of the phenotypic variation observed. Based on the rapid linkage disequilibrium (LD) and the high density of SNPs in the association population, qAA8 was further localised to a smaller genomic region of approximately 1500 bp. A high-resolution map of the qAA8 region will be useful towards a marker-assisted selection (MAS) of A. flavus resistance and a characterisation of the causal gene.

No MeSH data available.


Related in: MedlinePlus

Frequency distribution of natural variations in the amount of aflatoxin (AA, ug/kg) and the score of resistance to A. flavus infection (RAI).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5037484&req=5

toxins-08-00258-f001: Frequency distribution of natural variations in the amount of aflatoxin (AA, ug/kg) and the score of resistance to A. flavus infection (RAI).

Mentions: The means, standard deviations, skewness, kurtosis, ranges and broad-sense heritability values, and analyses of variance (ANOVA) for the AA and RAI score are presented in Table 1. The ANOVA indicated that the AA and RAI score were significantly affected by plant line genotype (p < 0.01). The AA in the two populations and the RAI score in the association population displayed a wide range. Compared with the resistant RA line, the susceptible line (M53) had a significantly higher AA, and the transgressive segregation of this trait was apparent in the RIL population. For the AA, there was a 7.4-fold difference between the lines in the RIL population and a 3.4-fold difference between the lines in the association population. For the RAI score, there was a 3.3-fold difference between the lines in the association population in 2013 and a 4.6-fold difference between the lines in the association population in 2014. The AA and RAI score showed a similar variation range in the association population compared to the RIL population. The RAI score variation range for the RIL population is described in our previous study [17]. The AA distribution in the RIL population and the AA and RAI score in the association population were relatively normal (Figure 1) and consistent with the small absolute values of skewness and kurtosis (less than 1.0) for the two traits (Table 1). The heritability (h2) estimates for the AA and RAI score ranged from 78% to 85% (Table 1). Overall, the maize plants clearly exhibited considerable natural variations in the AA and RAI score and displayed a high genetic diversity.


Confirmation and Fine Mapping of a Major QTL for Aflatoxin Resistance in Maize Using a Combination of Linkage and Association Mapping
Frequency distribution of natural variations in the amount of aflatoxin (AA, ug/kg) and the score of resistance to A. flavus infection (RAI).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037484&req=5

toxins-08-00258-f001: Frequency distribution of natural variations in the amount of aflatoxin (AA, ug/kg) and the score of resistance to A. flavus infection (RAI).
Mentions: The means, standard deviations, skewness, kurtosis, ranges and broad-sense heritability values, and analyses of variance (ANOVA) for the AA and RAI score are presented in Table 1. The ANOVA indicated that the AA and RAI score were significantly affected by plant line genotype (p < 0.01). The AA in the two populations and the RAI score in the association population displayed a wide range. Compared with the resistant RA line, the susceptible line (M53) had a significantly higher AA, and the transgressive segregation of this trait was apparent in the RIL population. For the AA, there was a 7.4-fold difference between the lines in the RIL population and a 3.4-fold difference between the lines in the association population. For the RAI score, there was a 3.3-fold difference between the lines in the association population in 2013 and a 4.6-fold difference between the lines in the association population in 2014. The AA and RAI score showed a similar variation range in the association population compared to the RIL population. The RAI score variation range for the RIL population is described in our previous study [17]. The AA distribution in the RIL population and the AA and RAI score in the association population were relatively normal (Figure 1) and consistent with the small absolute values of skewness and kurtosis (less than 1.0) for the two traits (Table 1). The heritability (h2) estimates for the AA and RAI score ranged from 78% to 85% (Table 1). Overall, the maize plants clearly exhibited considerable natural variations in the AA and RAI score and displayed a high genetic diversity.

View Article: PubMed Central - PubMed

ABSTRACT

Maize grain contamination with aflatoxin from Aspergillusflavus (A. flavus) is a serious health hazard to animals and humans. To map the quantitative trait loci (QTLs) associated with resistance to A. flavus, we employed a powerful approach that differs from previous methods in one important way: it combines the advantages of the genome-wide association analysis (GWAS) and traditional linkage mapping analysis. Linkage mapping was performed using 228 recombinant inbred lines (RILs), and a highly significant QTL that affected aflatoxin accumulation, qAA8, was mapped. This QTL spanned approximately 7 centi-Morgan (cM) on chromosome 8. The confidence interval was too large for positional cloning of the causal gene. To refine this QTL, GWAS was performed with 558,629 single nucleotide polymorphisms (SNPs) in an association population comprising 437 maize inbred lines. Twenty-five significantly associated SNPs were identified, most of which co-localised with qAA8 and explained 6.7% to 26.8% of the phenotypic variation observed. Based on the rapid linkage disequilibrium (LD) and the high density of SNPs in the association population, qAA8 was further localised to a smaller genomic region of approximately 1500 bp. A high-resolution map of the qAA8 region will be useful towards a marker-assisted selection (MAS) of A. flavus resistance and a characterisation of the causal gene.

No MeSH data available.


Related in: MedlinePlus