Monday, November 13, 2006
59-2

Joint Analysis of Insect Feeding Damage in Maize.

Andrew Hauck and Martin Bohn. Univ of Illinois at Champaign-Urbana, Crop Science Dept, 1102 S Goodwin Ave, Urbana, IL 61801

The past two decades of plant breeding have resulted in the publication of many studies identifying quantitative trait loci (QTL) using molecular markers. Quantitative genetic theory suggests that for a given trait, there are many QTL of small effect contributing to the overall phenotype of an individual. The relatively large effects of environmental variation and small population sizes commonly used in QTL studies limit the power of QTL detection and may explain the difficulty in repeatability of QTL experiments. The purpose of this study was to ascertain the advantages of combining data from multiple QTL studies on common traits for enhanced power of QTL detection. A joint analysis was conducted using genetic and phenotypic data collected from a number of studies examining the segregation of alleles related to cell wall strength and insect resistance in maize populations derived from crosses between two inbreds. Parental inbreds adapted to temperate and tropical growing conditions with contrasting levels of insect feeding damage are represented in the combined experimental population, capturing a broad range of the natural genetic variation for this trait in maize. Marker genotypes were standardized for common identification of inheritance from a resistant or susceptible parent, then pooled within chromosomal bins. Analyses of variance was performed to associate genotypes within bins with trait expression. The level of significance was determined with a re-sampling strategy. Bins carrying genes contributing to the resistance of maize against stem borer larvae leaf feeding were found on all chromosomes except for chromosome 2. In some cases bins with no reported resistance QTL, as determined from the original studies, were found to be significant. A number of significant bins match the genomic locations of candidate genes, such as members of the lignin pathway, and QTL for other correlated traits, like cell wall digestibility.


Handout (.pdf format, 48.0 kb)