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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.


Epistatic effects on the amount of aflatoxin (AA). The lines denote epistatic associations between QTLs.
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toxins-08-00258-f003: Epistatic effects on the amount of aflatoxin (AA). The lines denote epistatic associations between QTLs.

Mentions: To examine epistatic interactions, six pairs of interacting QTLs were mapped to chromosomes 1, 3, 8 and 10 (Table 4, Figure 3). Two pairs of epistatic QTL interactions on chromosomes 8 and 10 reduced the AA by 1.51 and 1.75 μg per kilogram of maize kernel, respectively, whereas the remaining pairs increased the AA level. The phenotypic variation explained by these interactions ranged from 14% to 23%. The additive QTL on chromosome 8, qAA8, did not show a significant epistatic interaction.


Confirmation and Fine Mapping of a Major QTL for Aflatoxin Resistance in Maize Using a Combination of Linkage and Association Mapping
Epistatic effects on the amount of aflatoxin (AA). The lines denote epistatic associations between QTLs.
© Copyright Policy
Related In: Results  -  Collection

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

toxins-08-00258-f003: Epistatic effects on the amount of aflatoxin (AA). The lines denote epistatic associations between QTLs.
Mentions: To examine epistatic interactions, six pairs of interacting QTLs were mapped to chromosomes 1, 3, 8 and 10 (Table 4, Figure 3). Two pairs of epistatic QTL interactions on chromosomes 8 and 10 reduced the AA by 1.51 and 1.75 μg per kilogram of maize kernel, respectively, whereas the remaining pairs increased the AA level. The phenotypic variation explained by these interactions ranged from 14% to 23%. The additive QTL on chromosome 8, qAA8, did not show a significant epistatic interaction.

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.