Abstract
Maize kernel is exposed to several fungal species, most notably Fusarium verticillioides, which can contaminate maize kernels with fumonisins. In an effort to increase genetic gains and avoid the laborious tasks of conventional breeding, the use of marker-assisted selection or genomic selection programs was proposed. To this end, in the present study a Genome Wide Association Study (GWAS) was performed on 339 RILs of a Multiparental Advanced Generation InterCross (MAGIC) population that had previously been used to locate Quantitative Trait Locus (QTL) for resistance to Fusarium Ear Rot (FER). Six QTLs for fumonisin content were detected in the bins 3.08, 4.07, 4.10, 7.03-7.04, 9.04-9.05 and 10.04-10.5. Five of the six QTLs collocate in regions where QTLs for FER were also found. However, the genetic variation for fumonisin content in kernel is conditioned by many other QTLs of small effect that could show QTL x environment interaction effects. Although a genomic selection approach to directly reduce fumonisin content in the kernel could be suitable, improving resistance to fumonisin content by genomic selection for FER would be more advisable.
Highlights
Maize kernel is exposed to several fungal genera, including Fusarium, Aspergillus or Penicillium, which can contaminate maize kernels with mycotoxins
Neither significant genotypic (− 0.07 ± 0.11) and phenotypic (− 0.06 ± 0.04) correlation coefficients were found between fumonisin content and days to silking
Large and significant differences among inbred founders were detected for fumonisin content, but the estimated heritability for fumonisin content in the Multiparental Advanced Generation InterCross (MAGIC) population derived from those founders was low highlighting the importance of moving to breeding methodologies assisted by molecular markers with stable effects across environments
Summary
Maize kernel is exposed to several fungal genera, including Fusarium, Aspergillus or Penicillium, which can contaminate maize kernels with mycotoxins. In Spain, Fusarium verticillioides predominates over other species. This species produces fumonisins that, in addition to causing multiple disorders in animals [1], have been classified as possibly carcinogenic by the International Agency for Research on Cancer [2]. In contrast to inbred panels, multiparental populations largely avoid the potentially confounding influence of population structure and increase the frequency of panel rare alleles which could be of particular interest for breeding [17]. An efficient MAGIC population has clear advantages over other approaches: it has greater genetic variation than biparental populations; it has a balanced allelic frequency since all founders contribute ; and a uniform and high recombination rate that increases the resolution of genetic analysis, mapping and gene isolation [18]
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