Genome‐Wide Association Mapping of Aspergillus flavus and Aflatoxin Accumulation Resistance in Maize

Abstract

Contamination of maize (Zea mays L.) with aflatoxin, produced by the fungus Aspergillus flavus Link, has severe health and economic consequences. Efforts to reduce aflatoxin accumulation in maize have focused on identifying and selecting germplasm with natural host resistance factors, and several maize lines with significantly reduced aflatoxin accumulation have been identified. Past linkage mapping studies have identified quantitative trait loci (QTL) that consistently reduce aflatoxin levels in maize. In addition, an association mapping panel of 300 maize inbred lines was previously created specifically for the dissection of aflatoxin accumulation resistance. Here we report the results of a genome‐wide association study (GWAS) using this panel of testcrossed maize hybrids. Each of the inbred parents of the testcrossed hybrids was genotyped by sequencing to generate 261,184 robust single nucleotide polymorphisms (SNPs), and the entire panel was phenotyped for aflatoxin accumulation following inoculation with A. flavus in multilocation, replicated field trials. Results uncovered 107 SNPs associated with aflatoxin accumulation in one or more environments in the association panel at a probability level between 9.78 × 10−6 and 2.87 × 10−10. Eight SNP trait associations were found with a false discovery rate (FDR) of less than 10% (p < 3.83 × 10−7). These SNPs occur within the sequence of three uncharacterized genes. Variants in 25 other genomic regions showing high association values over more than one environment are also presented. These genomic regions are undergoing validation studies and will be of use to dissect the resistance to aflatoxin accumulation and improve this trait.

Quantitative trait loci for Fusarium and Gibberella ear rot resistance in Argentinian maize germplasm

“…For Gibberella ear rot resistance, QTLs were reported in bins 2.04, 2.06 and 2.08, 3.02, 3.04, 3.05, 3.06, 5.04, 5.05 and 5.06 in sources of resistance from Canada, Germany and Uganda (Liakat Ali et al 2005;Martin et al 2011Martin et al , 2012Tembo et al 2014). The same genome regions seem to be also important for Aspergillus ear rot resistance (Robertson-Hoyt et al 2007;Mideros et al 2014;Warburton et al 2015). The most important QTL mapped in bin 2.03.…”

Genomic‐Wide Association Study of Popping Expansion in Tropical Popcorn and Field Corn Germplasm

“…Association mapping studies have been widely reported for foliar diseases (Kump et al, 2011; Poland et al, 2011; Gowda et al, 2015; Olukolu et al, 2016), ear rot diseases (Zila et al, 2014; Warburton et al, 2015; Han et al, 2018), flowering time, and plant architecture (Wallace et al, 2016) in maize. In this study, we applied a comprehensive GWAS for popping expansion using 165,089 SNPs markers in 183 inbred lines with 2 yr of trial data.…”

Meta‐Analysis of QTL Studies for Resistance to Fungi and Viruses in Maize

“…Different methods have been used to identify QTL and genes related to resistance to maize diseases such as linkage mapping on biparental populations and association mapping on diverse populations (Warburton et al, 2015). This has contributed to the heterogeneity among published results.…”