Genes and genetic mechanisms contributing to fall armyworm resistance in maize

Authors: Warburton, Marilyn; Woolfolk, Sandra; Smith, Jesse; Hawkins, Leigh; Castano-Duque, Lina; Lebar, Matthew; Williams, William

Submitted to: The Plant Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2023
Publication Date: 3/2/2023
Citation: Warburton, M.L., Woolfolk, S.W., Smith, J.S., Hawkins, L.K., Castano-Duque, L.M., Lebar, M.D., Williams, W.P. 2023. Genes and genetic mechanisms contributing to fall armyworm resistance in maize. The Plant Genome. 16(2):e20311. https://doi.org/10.1002/tpg2.20311.
DOI: https://doi.org/10.1002/tpg2.20311

Interpretive Summary: Maize (Zea mays L.) is a crop of major economic and food security importance globally. The fall armyworm (FAW), Spodoptera frugiperda can devastate entire maize crops, especially in countries or markets that do not allow the use of transgenic crops. Host-plant insect resistance conferred by naturally occurring maize genes, is an economical and environmentally benign way to control FAW. We grew 289 different kinds of maize in the field and put FAW larvae on them, and then measured damage to the leaves. In this study, we identified 30 maize lines that showed significantly less damage than the rest. We also identified 7 genes and several metabolic pathways, the mechanisms that cells use to build important proteins and chemicals, that were associated with reduced insect feeding damage. We can now use this information to breed new, resistant maize varieties for farmers.

Technical Abstract: Maize (Zea mays L.) is a crop of major economic and food security importance globally. The fall armyworm (FAW), Spodoptera frugiperda can devastate entire maize crops, especially in countries or markets that do not allow the use of transgenic crops. Host-plant insect resistance conferred by naturally occurring maize genes, is an economical and environmentally benign way to control FAW, and this study sought to identify maize lines, genes, and pathways that contribute to resistance to FAW. Of 289 maize lines phenotyped for FAW damage in artificially infested, replicated field trials over three years, 30 were identified with good levels of resistance that would make excellent breeding donor lines for introgression breeding of FAW resistance into elite but susceptible hybrid parents. The 289 lines were also genotyped by sequencing to provide SNP markers for a Genomewide Association Study, which was followed by a metabolic pathway analysis using the Pathway Association Study Tool (PAST). GWAS identified 15 SNPs linked to 7 genes, and PAST identified multiple pathways, associated with FAW damage. Top pathways, and thus useful resistance mechanisms for further study, include the biosynthesis of carotenoids, particularly zeaxanthin; 1,4-dihydroxy-2-naphthoate biosynthesis II, precursor to vitamin K2, and of known antibiosis agents; and hormone signaling pathways.