Quantitative Trait Loci for First- and Second-Generation European Corn Borer Resistance Derived from the Maize Inbred Mo47

Abstract

fied QTLs for resistance to 1ECB and 2ECB. Schö n et al. (1991) identified four QTLs for resistance to 1ECB European corn borer (ECB), Ostrinia nubilalis (Hü bner), family on chromosomes 1, 4, 6, and 9 in F 3 families from the Crambidae, order Lepidoptera, is a serious insect pest of maize (Zea mays L.) in the USA. Understanding the genetic basis for ECB resis-cross of Mo17 (susceptible) and H99 (resistant). Schö n tance should increase the efficiency of breeding insect-resistant germ-et al. (1993) identified seven QTLs for resistance to plasm. The objectives of this study were to determine the number, 2ECB in an F 3 population derived from the cross of B73 genomic positions, and genetic effects of quantitative trait loci (QTL) (susceptible) ϫ B52 (resistant) on chromosomes 1 (two conferring resistance to leaf feeding damage cause by first-generation QTLs), 2 (two QTLs), 3, 7, and 10. Lee (1993) reported ECB (1ECB, defined as the trait of leaf feeding damage) and stalk 16 QTLs for resistance to 2ECB in three populations tunneling caused by second-generation ECB (2ECB, defined as the of F 3 families derived from crosses of B73 ϫ B52, B73 ϫ trait of stalk tunnel damage). The study included 244 F 2:3 families DE811 (resistant), and Mo17 (susceptible) ϫ B52. derived from the cross of B73Ht (susceptible) ϫ Mo47 (resistant). Beavis et al. (1994) identified QTLs for resistance to Inbred Mo47 represented a novel source of ECB resistance containing 2ECB on chromosomes 7, 8, and 9 from topcrosses and 50% tropical germplasm. The QTL analyses for three individual environments and combined across environments were performed by com-F 4 families from the cross of B73 ϫ Mo17. In the F 3 posite interval mapping using QTL Cartographer. Nine QTLs were families derived from the cross of two European maize identified for 1ECB on chromosomes 1 (three QTLs), 2, 4 (two QTLs), lines, D06 and D408, Bohn et al. (2000) identified six 5, 6, and 8, on the basis of data combined across environments. SevenQTLs for ECB tunnel length on chromosomes 1, 3, 5QTLs for 2ECB were found on chromosomes 2, 5 (two QTLs), 6 (two QTL), 9, and 10. Although some of the differences (two QTLs), 8, and 9. Several of the QTLs detected are located in in QTLs detected may be due to methods used in meagenomic regions reported for resistance to other stem borer pests of suring ECB damage, these results suggest that different maize. Inconsistency of QTLs across environments complicates use

Phenotypic versus marker-assisted selection for stalk strength and second-generation European corn borer resistance in maize

“…It is likely that the phenotypic data used in population 4 were superior to those used in population 3, resulting in better estimates of QTL positions and effects. In fact, the QTL from population 4 accounted for 57.5% of the phenotypic variation (Jampatong et al 2002), while the QTL from population 3 accounted for only 16.1%.…”

“…Populations 1, 2, and 3 (Flint-Garcia 2001;Flint-Garcia et al 2003) and population 4 (Jampatong 1999a;Jampatong et al 2002) were used to make selections for high and low RPR, and resistance and susceptibility to 2-ECB. The pedigrees of the four populations are population 1, 'MoSCSSS-High RPR''MoSQB-Low SCS' (stalk crushing strength, an alternative measurement of stalk strength; 282 families); population 2, 'MoSCSSS-High RPR''MoSCSSS-Low RPR' (291 families); population 3, 'MoSCSSS-High RPR''Mo47' (291 families); and population 4, 'Mo47''B73' (244 families).…”

“…Rind penetrometer resistance was determined about 2 weeks after anthesis for 10 competitive plants plot 1 as previously described (Flint-Garcia et al 2003). For 2-ECB evaluation, 10 plants plot 1 were artificially infested with neonate ECB larvae as previously described (Jampatong et al 2002). Approximately 8 weeks after infestation, stalks from infested plants were split longitudinally from one node above the primary ear to the ground and the length of the tunnels caused by ECB boring within the stalk, i.e., tunnel length (TL) per plant was visually estimated.…”

“…It was somewhat surprising that QTL from population 4 were more effective in selection for resistance than QTL from population 3. The 2-ECB data for population 4 that were used in the original QTL analysis were obtained from three environments with three replications each (Jampatong et al 2002), while data for the population 3 QTL analysis were based on a single environment with three replications (Flint-Garcia 2001). It is likely that the phenotypic data used in population 4 were superior to those used in population 3, resulting in better estimates of QTL positions and effects.…”

“…In a previous study, we found that RPR was controlled by many genes with small-tomoderate effects (Flint-Garcia et al 2003). Cardinal et al (2001), Flint-Garcia (2001 and Jampatong et al (2002) found that resistance to 2-ECB was conferred by several genes with small-to-moderate effects.…”