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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.


Quantitative trait loci (QTL) for the amount of aflatoxin (AA, μg/kg) on maize chromosome 8. The designation on the left is the genetic distance (centi-Morgan, cM) and marker name. The right shows the likelihood odds (LOD) scores of the QTL on the chromosome.
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toxins-08-00258-f002: Quantitative trait loci (QTL) for the amount of aflatoxin (AA, μg/kg) on maize chromosome 8. The designation on the left is the genetic distance (centi-Morgan, cM) and marker name. The right shows the likelihood odds (LOD) scores of the QTL on the chromosome.

Mentions: The QTL analysis revealed one significant additive QTL for the AA—qAA8—on chromosome 8 (Table 3, Figure 2). This QTL explained 18.23% of the phenotypic variation. Moreover, this QTL was previously implicated in controlling the RAI score in the same RIL population [17]. The additive effect values indicated that the resistant parent RA alleles decreased both the AA and RAI score at this locus. Thus, this QTL may be a target region for identifying genes associated with an improved A. flavus resistance.


Confirmation and Fine Mapping of a Major QTL for Aflatoxin Resistance in Maize Using a Combination of Linkage and Association Mapping
Quantitative trait loci (QTL) for the amount of aflatoxin (AA, μg/kg) on maize chromosome 8. The designation on the left is the genetic distance (centi-Morgan, cM) and marker name. The right shows the likelihood odds (LOD) scores of the QTL on the chromosome.
© Copyright Policy
Related In: Results  -  Collection

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

toxins-08-00258-f002: Quantitative trait loci (QTL) for the amount of aflatoxin (AA, μg/kg) on maize chromosome 8. The designation on the left is the genetic distance (centi-Morgan, cM) and marker name. The right shows the likelihood odds (LOD) scores of the QTL on the chromosome.
Mentions: The QTL analysis revealed one significant additive QTL for the AA—qAA8—on chromosome 8 (Table 3, Figure 2). This QTL explained 18.23% of the phenotypic variation. Moreover, this QTL was previously implicated in controlling the RAI score in the same RIL population [17]. The additive effect values indicated that the resistant parent RA alleles decreased both the AA and RAI score at this locus. Thus, this QTL may be a target region for identifying genes associated with an improved A. flavus resistance.

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.