Date of Award
Doctor of Philosophy
The European corn borer is a significant pest of maize in temperate regions. Resistance to stalk tunneling damage from the second-generation larvae appears to be quantitatively inherited, and may be related to cell wall components (CWCs) in the leaf sheath and stalk. In order to identify quantitative trait loci (QTL) that affect resistance to stalk tunneling and clarify their association with QTL affecting cell wall components in the leaf sheath and stalk, two populations of B73 (susceptible to tunneling by ECB, low to intermediate concentrations of CWCs) x De811 (resistant, high CWCs) were developed, one consisting of 147 F3 lines and the other of 191 recombinant inbred lines (RILs). Both populations were artificially infested with ECB larvae at pollen shed, and stalks were split at 60 days after infestation and the amount of tunneling was recorded. These populations were also analyzed for concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) in the leaf sheaths and stalks. The samples were scanned using near infrared spectroscopy and prediction equations were developed using data collected from a subset of samples analyzed using the van Soest detergent method. Composite interval mapping (CIM) was used to detect QTL for each trait, and the relationships between the QTL detected for the same traits in different generations and among different traits in the same generation were examined. Seven and fourteen QTL for stalk tunneling were observed in the mean environments for the F3 and RI lines of B73 x De811, four and twelve of which, respectively, are linked to QTL for CWCs. The previously reported genetic correlations for ECB stalk tunneling with CWCs in the F3 lines (rg = -0.11 to -0.33) indicate that a genetic association may exist between the two traits. However, the genetic correlations for the RIL were -0.03 to 0.08, raising the possibility that the correlations observed in the F 3 lines were either due to environmental factors or the result of linkage disequilibrium. Factors other than concentrations of CWCs appear to be associated with the expression of resistance to stalk tunneling in this population.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu
Matthew David Krakowsky
Krakowsky, Matthew David, "Identification of quantitative trait loci associated with cell wall components and resistance to the European corn borer (Ostrinia nubilalis (Hübner)) in maize (Zea mays L.) " (2001). Retrospective Theses and Dissertations. 653.