The Genetic Basis of ZmBGLU17 in Modulating Maize Resistance to the Fall Armyworm Spodoptera Frugiperda

Maize, as a globally important food crop, is threatened by pests including the fall armyworm (FAW, Spodoptera frugiperda) throughout its production. Current management strategies are largely limited to conventional chemical insecticides and transgenic maize varieties. However, the identification and functional characterization of endogenous insect-resistance genes within maize inbred line populations, as well as the underlying molecular mechanisms governing resistance, remain poorly understood. Here, we systematically evaluate FAW resistance on 300 modern maize inbred lines and 200 recombinant inbred lines (RIL) populations in field, followed by quantitative trait locus (QTL) and genome-wide association studies (GWAS) mapping to screen candidate genes. Our data demonstrate that a β-glucosidase ZmBGLU17 was identified as a key FAW resistance gene, which contributes to the accumulation of two defense metabolites, lignin and DIMBOA. Overexpression of the ZmBGLU17 gene confers enhanced resistance to the FAW by significantly reducing larval survival. Haplotype analysis revealed two distinct haplotypes, with haplotype 1 demonstrating significantly enhanced resistance to FAW infestation compared with haplotype 2. Jointly, our research identified ZmBGLU17 as a key resistance-associated gene against FAW and confirmed its functional role through rigorous genetic validation. Furthermore, haplotype analysis revealed prevalent resistance-linked haplotypes, thereby establishing a molecular foundation for the development of FAW-resistant maize inbred lines.