Location: Corn Host Plant Resistance ResearchTitle: Mapping of quantitative trait loci for resistance to fall armyworm and southwestern corn borer leaf-feeding damage in maize
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2017
Publication Date: 2/25/2018
Citation: Womack, E.D., Warburton, M.L., Williams, W.P. 2018. Mapping of quantitative trait loci for resistance to fall armyworm and southwestern corn borer leaf-feeding damage in maize. Crop Science. 58(2):529-539. https://doi.org/10.2135/cropsci2017.03.0155.
Interpretive Summary: Fall armyworm (FAW) and southwestern corn borer (SWCB) are damaging insect pests of corn that cause yield and economic loss. A previous study identified regions on chromosomes that contain genes that contribute to the reduction of damage caused by these insects in a corn population created by breeding an insect resistant parent, Mp704, with an insect susceptible parent, Mo17. Chromosomal markers called simple sequence repeat (SSR) were used to determine the location of these regions resulting in a chromosome map. The current study reports a more detailed map of the Mp704 x Mo17 corn population created by adding 159 new markers, SSR and single nucleotide polymorphism (SNP), to the original map of 75 SSRs to re-evaluate the regions of interest. Analysis identified seven regions on chromosomes that explained 61% of the difference in FAW leaf-feeding damage in the Mp704 x Mo17 population. Six regions explained 53% of the variation for SWCB. Possible genes responsible for the reduction of leaf-feeding damage by the FAW and SWCB fall in the regions identified in the current study include glossy15 (chromosome 9), the ribosome-inactivating protein (chromosome 7) and pathogenesis-related protein (chromosome 8). Adding significantly more markers to the previously reported map allowed a better assessment of chromosome regions that could deter insects from eating the corn plant which could improve breeding applications and the detection of possible genes controlling FAW and SWCB resistance.
Technical Abstract: Fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), and southwestern corn borer (SWCB), Diatraea grandiosella Dyar are damaging insect pests of maize resulting in significant yield and economic losses. A previous study identified quantitative trait loci (QTL) that contribute to reduced leaf-feeding damage by these insects in the maize mapping population created by crossing Mp704 (resistant) x Mo17 (susceptible). The current study reports a more complete map by adding 159 simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers to the original map of 75 SSRs for QTL analyses. Composite interval mapping (CIM) and multiple interval mapping (MIM) identified seven QTL (including one new one in this study) and one interaction (explaining 61% of the phenotypic variation) for FAW, and six QTL (including two new ones) and one interaction (explaining 53%) for SWCB damage averaged across all environments. Candidate genes glossy15, the ribosome-inactivating protein (rip2) and pathogenesis-related protein (prp1) co-locate with QTL identified in the current study in bins 9.03, 7.04, and 8.03, respectively. The addition of significantly more markers to the previously reported map allowed a better assessment of QTL positions and effects, which can improve breeding applications and the detection of candidate genes controlling FAW and SWCB resistance.