Wednesday, November 15, 2006

Detection of Donor Alleles for Enhanced Starch Concentration in the Illinois Low Protein Maize Strain.

Torbert Rocheford and H. Sofia Silva. Univ of Illinois, AW-101 Turner Hall, Urbana, IL 61801

There is interest in modifying levels of starch, protein and oil on maize grain for specific end uses. We are interested in breeding for higher levels of starch to enhance starch fermentation efficiency to produce ethanol. Quantitative Trait Loci (QTL) associated with kernel composition traits would facilitate the development of maize inbreds and hybrids with desirable properties and levels of components, enabling better and more efficient conversion to secondary products.To identify quantitative trait loci (QTL) affecting kernel composition traits in maize, the Illinois Low protein cycle 90 (ILP90), previously developed by selection for low protein (resulting in extreme high levels of starch), was crossed to B73. The cross was then backcrossed to B73 and selfed one time producing 150 BC1S1 families. The BC1S1 population was then selfed  two more generations producing 138 BC1S3 families. By evaluating kernel composition traits in a (ILP90×B73)B73 background we are looking for donor alleles in the ILP strain that would improve inbreds and likely increase hybrid starch levels. Starch, protein, oil, and kernel weight were measured in grain samples of (ILP90×B73) B73 S1 and S3 families using a Near Infrared Reflectance (NIR) instrument. QTL for the individual traits and Principal Components Analysis (PCA) were performed in both populations individually and a combined model was used to detect consistent QTL across generations. QTL associated with starch concentration was detected near the location of brittle1 (bt1) and amylose extender1 (ae1) in the BC1S1 and also for the combined analysis. The majority of QTL associated with starch concentration did not map to starch structural biosynthetic genes, suggesting that unknown regulatory loci may influence quantitative variation for starch concentration.