Mapping quantitative trait loci for resistance to fall armyworm (Lepidoptera: Noctuidae) leaf-feeding damage in maize inbred Mp705

Authors: Womack, Erika; Williams, William; Smith, Jesse; Warburton, Marilyn; BHATTRAMAKKI, DINAKAR - Corteva Agriscience

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2019
Publication Date: 1/8/2020
Citation: Womack, E.D., Williams, W.P., Smith, J.S., Warburton, M.L., Bhattramakki, D. 2020. Mapping quantitative trait loci for resistance to fall armyworm (Lepidoptera: Noctuidae) leaf-feeding damage in maize inbred Mp705. Journal of Economic Entomology. 113(2):956-963. https://doi.org/10.1093/jee/toz357.
DOI: https://doi.org/10.1093/jee/toz357

Interpretive Summary: Interpretive Summary The fall armyworm (FAW) is an insect pest that feeds on all above-ground portions of the corn plant and causes significant yield loss. It has long been a major pest of corn in the southern United States, but in the past five years, it has spread across Africa and Asia with devastating consequences. This study used many chromosomal markers known as single nucleotide polymorphisms (SNP) and simple sequence repeats (SSR) to determine the location of chromosomal regions in a germplasm line of corn, Mp705, developed and released as a source of naturally occurring genetic resistance to FAW leaf feeding damage. Saturating the chromosomal map with markers allowed for better assessment and identification of chromosomal regions that contain genes that deter FAW from eating the corn plant and reducing the yield and quality of grain. Our analysis identified two major chromosomal regions of Mp705 that were important to reducing leaf-feeding damage by FAW. One region was found in previous studies, confirming its contribution to resistance, and the other major region is novel and may offer a new means to deter the FAW. Plant breeders will use this information and the known sources of resistance such as Mp705 or other germplasm lines developed by USDA-ARS to conduct marker assisted selection for reduced FAW damage. This will enable them to enhance the level of FAW resistance in germplasm lines, hybrids, or varieties adapted to their localities, whether that be the United States, Africa, or Asia.

Technical Abstract: Abstract The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a serious pest of maize (Zea mays L.). This migrant insect devastates maize plants in many countries threatening the livelihood of millions. In this study, quantitative trait loci (QTL) were mapped to identify chromosomal regions that control resistance to FAW leaf-feeding and to identify molecular markers linked to the target loci for use in marker-assisted selection (MAS). A bi-parental mapping population, comprising 243 F2:3 families derived from the cross Mp705 (resistant) x Mp719 (susceptible), was genotyped with 1,276 single nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers and phenotyped for FAW leaf-feeding damage after artificial infestation over three years. Major QTL were identified in bins 4.06 and 9.03 that together explained 35.7% of the phenotypic variance based on the data combined over all environments. Both parents contributed beneficial alleles, but the resistant parent, Mp705, contributed the beneficial allele for both large effect QTL and most of the small effect QTL identified in this study. The QTL in bin 9.03 co-locates with a previously identified QTL related to leaf-feeding resistance in maize by lepidopteran insects. The QTL in bin 4.06 is a novel QTL detected in this study that may offer a new source of resistance for the improvement of FAW leaf-feeding damage in maize. By identifying beneficial alleles derived from Mp705, our results open avenues for the implementation of an integrated MAS approach. Keywords: Quantitative trait loci, Mp705, maize, fall armyworm, host-plant resistance