Genetic Basis of Maize Resistance to Multiple Insect Pests: Integrated Genome-Wide Comparative Mapping and Candidate Gene Prioritization
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Date
2020
Journal Title
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Genes
Abstract
Several species of herbivores feed on maize in field and storage setups, making the
development of multiple insect resistance a critical breeding target. In this study, an association
mapping panel of 341 tropical maize lines was evaluated in three field environments for resistance to
fall armyworm (FAW), whilst bulked grains were subjected to a maize weevil (MW) bioassay and
genotyped with Diversity Array Technology’s single nucleotide polymorphisms (SNPs) markers.
A multi-locus genome-wide association study (GWAS) revealed 62 quantitative trait nucleotides
(QTNs) associated with FAW and MW resistance traits on all 10 maize chromosomes, of which,
47 and 31 were discovered at stringent Bonferroni genome-wide significance levels of 0.05 and 0.01,
respectively, and located within or close to multiple insect resistance genomic regions (MIRGRs)
concerning FAW, SB, and MW. Sixteen QTNs influenced multiple traits, of which, six were associated
with resistance to both FAWandMW, suggesting a pleiotropic genetic control. Functional prioritization
of candidate genes (CGs) located within 10–30 kb of the QTNs revealed 64 putative GWAS-based
CGs (GbCGs) showing evidence of involvement in plant defense mechanisms. Only one GbCG
was associated with each of the five of the six combined resistance QTNs, thus reinforcing the
pleiotropy hypothesis. In addition, through in silico co-functional network inferences, an additional
107 network-based CGs (NbCGs), biologically connected to the 64 GbCGs, and di erentially expressed
under biotic or abiotic stress, were revealed within MIRGRs. The provided multiple insect resistance
physical map should contribute to the development of combined insect resistance in maize.
Description
Keywords
Combined insect resistance, QTNs, Functional prioritization, Fall armyworm, Maize weevil, Stem borers
Citation
Badji, A., Kwemoi, D. B., Machida, L., Okii, D., Mwila, N., Agbahoungba, S., ... & Rubaihayo, P. (2020). Genetic basis of maize resistance to multiple insect pests: integrated genome-wide comparative mapping and candidate gene prioritization. Genes, 11(6), 689. doi:10.3390/genes11060689