QTL mapping for resistance to European corn borer (Ostrinia nubilalis Hb.) in early maturing European dent maize (Zea mays L.) germplasm and comparison of genomic regions for resistance across two populations of f 3 families

The European corn borer (ECB, Ostrinia nubilalis Hubner) is a major pest of maize in central Europe. The objectives of our study were to (1) identify QTL for resistance to ECB, (2) estimate their genetic effects, and (3) investigate the consistency of QTL across two different populations. A total of 230 F 2:3 families derived from cross 1396A (resistant) x F478 (susceptible) were used for QTL analyses. Each F 2:3 family was evaluated for resistance traits tunnel length (TL), stalk damage ratings (SDR), and relative grain yield (RGY) using manual infestation with ECB larvae. The agronomic traits comprised grain yield under insecticide protection (GYP) and manual infestation (GYI), date of anthesis (ANT), dry matter content (DMC), and in vitro digestible organic matter (IV-DOM) of stover. The field experiment was performed with two replications in two environments in 1995. Two QTL for SDR and two QTL for TL were detected explaining 24.7% and 26.0% of the genotypic variance (σ 2 g), respectively. For agronomic traits one to three QTL were found, explaining between 2.0% and 11.8% of σ 2 g. No common QTL for resistance traits were found across population 1396AxF478 and a second population of 230 F 2:3 families derived from cross D06 (resistant) x D408 (susceptible). Two QTL for IVDOM and DMC were in common among both populations. Due to the low consistency of QTL across populations, marker-assisted selection (MAS) is not recommended for improving ECB resistance in early maturing dent germplasm.