Location: Corn Insects and Crop Genetics ResearchTitle: Interaction of genetic mechanisms regulating methionine concentration in maize grain
|HUFFMAN, RYAN - Iowa State University|
|POLLAK, LINDA - Retired ARS Employee|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/2016
Publication Date: 7/14/2016
Citation: Huffman, R.D., Edwards, J.W., Pollak, L.M., Scott, M.P. 2016. Interaction of genetic mechanisms regulating methionine concentration in maize grain. Crop Science. 56(5):2379-2389. https://doi.org/10.2135/cropsci2015.10.0633..
Interpretive Summary: Methionine is an essential component of poultry diets. Normally methionine is provided as a supplement that adds to the cost of the diet. An alternative approach is to base a diet on corn that is bred to contain elevated methionine levels. This approach reduces the cost of the diet. Several types of high methionine corn have been developed by researchers. In this work we tested different combinations of these high methionine corn varieties to identify the combinations with the best perormance. We learned that some types of high methionine work better in combination with other types. This information can be used by plant breeders to develop new hybrids with elevated methionine levels. This will allow poultry producers to formulate healthy diets for less cost, resulting in higher profits for poultry producers and/or lower costs to consumers of poultry products such as eggs and meat.
Technical Abstract: Methionine is a limiting amino acid in poultry diets so methionine supplementation is typically required to meet nutritional demands. Maize varieties with increased methionine levels have been developed utilizing three different approaches: i.) increased levels of the methionine-rich 10 kDa zein, ii.) disruption of protein deposition using the floury-2 (fl2) allele, and iii.) recurrent selection. The goal of this study was to characterize the interactions of these three mechanisms for increasing methionine in order to develop optimal breeding strategies for this limiting amino acid. A complete diallel mating design was used to produce all possible hybrid combinations which were analyzed by Griffing’s experimental method 3, model 1. The significantly negative GCA for RS2 suggests it did not perform well in hybrid combination while the significant SCAs suggest that some specific combinations of mechanisms worked well together. Analysis of grain quality traits by NIR revealed that the high methionine hybrid combinations had starch and oil concentrations similar to all other hybrids but had elevated protein concentrations. Our results suggest that dzr1 and recurrent selection are effective mechanisms to elevate methionine in hybrid combination and do not have an associated yield penalty, relative to other hybrids produced in the study, which supports their use in a high methionine maize breeding program.