Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2007
Publication Date: 8/1/2007
Citation: Brooks, T.D., Bushman, B.S., Williams, W.P., McMullen, M.D., Buckley, P.M. 2007. Genetic basis of resistance to fall armyworm (Lepidoptera: Noctuidae) and southwestern corn borer (Lepidoptera: Crambidae)leaf-feeding damage in maize. Journal of Economic Entomology. 100:1470-1475. Interpretive Summary: Corn lines that exhibit less leaf damage from fall armyworm and southwestern corn borer feeding than most commercially available corn hybrids have been developed and released by ARS. Larvae of these insect pests tend to grow more slowly on the resistant corn germplasm than on susceptible corn. Experiments were undertaken to determine the genetic basis of the inheritance of this resistance in two released lines, Mp704 and Mp708. This study identified genes or groups of genes responsible for reduced leaf feeding damage in the resistant line Mp708 and compared them with those genes found previously in Mp704 and investigated the relationship between resistance to southwestern corn borer and fall armyworm. Results indicated that a small number of genes influence similar resistance between the two lines. Four chromosomal regions were identified that reduced damage by both insects and appeared in both Mp704 and Mp708. The consistency between the lines suggests that transfer of resistance to new hybrids is feasible. Because only a few genes or groups of genes appear to be associated with resistance, their transfer from Mp704 or Mp708 into elite corn hybrids should be relatively straightforward using molecular techniques and markers identified in this study. Resistance to leaf feeding damage by both fall armyworm and southwestern corn borer can be enhanced simultaneously with these resistance genes.
Technical Abstract: To clarify the genetic basis of resistance to leaf feeding damage by fall armyworm and southwestern corn borer a study was undertaken to compare quantitative trait loci involved in two related resistant maize lines, Mp704 and Mp708. Models containing four and seven QTL explaining southwestern corn borer and fall armyworm resistance, respectively, were identified in Mp708. Key genomic regions influencing both traits are located on chromosomes 1, 5, 7, and 9. Several QTL for resistance were similar to those identified in Mp704 implying that genetic and biochemical mechanisms of resistance are shared between the two lines. QTL regions on chromosomes 1, 5, 7, and 9 contained resistance to both insects and were expressed in both resistant lines. These regions correspond with previously identified QTL related to resistance to other Lepidoptera suggesting that broad spectrum resistance to leaf feeding is primarily controlled by only a few genetic regions in this germplasm.