Mapping of quantitative trait loci for resistance to fall armyworm and southwestern corn borer leaf-feeding damage in maize.
Fall armyworm [FAW, Spodoptera frugiperda (J. E. Smith)] and southwestern corn borer (SWCB, Diatraea grandiosella Dyar) are damaging insect pests of maize (Zea mays L.) that result 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) × Mo17 (susceptible). The current study reports a more complete map by adding 151 simple sequence repeat (SSR) and single-nucleotide polymorphism markers to the original map of 73 SSRs for QTL analysis. Composite interval mapping (CIM) identified 24 QTL explaining up to 26.5% of the total phenotypic variation (chromosome bin 9.03), and multiple interval mapping (MIM) identified 36 QTL (including five new QTL found compared with the previous study) and 10 interactions for FAW leaf-feeding damage. Twenty-nine QTL explaining up to 29% of the total phenotypic variation (chromosome bin 7.02) were identified using CIM for SWCB leaf-feeding damage, and 21 QTL (including five new QTL) and 11 interactions were identified using MIM for this trait. The addition of significantly more markers to the previously reported map allowed for the identification of new QTL and a better assessment of QTL positions and effects, which can improve breeding applications and the detection of candidate genes controlling FAW and SWCB resistance.