Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/31/2005
Publication Date: 9/5/2005
Citation: Scott, M.P., Duvick, S.A. 2005. Identification of QTL controlling thermal properties of maize starch. Cereal Chemistry. 82(5):546-553. Interpretive Summary: Starch is used in many different products that require gelatinization of the starch by heating prior to use. The different uses require starches with different thermal properties. Thus, the thermal properties of starch are an important parameter in determining how well suited a starch is to a given purpose. Genetic modification can be used to develop starches with improved thermal properties, but has been limited by our poor understanding of the genetic control of starch thermal properties. In this study, we have examined the genetic control maize starch thermal properties. We identified regions of maize chromosomes that play a role in determining the thermal properties of maize starch. This information is valuable to scientists working to develop starches with modified thermal properties, because it suggests regions of the genome on which to focus their efforts. Ultimately, consumers and industries that use starch will benefit from starches with improved thermal properties because these starches will be better suited their end uses, resulting in higher quality products.
Technical Abstract: There is great interest in altering the thermal properties of starch because this would allow the development of starch with optimal properties for specific end uses. Genetic manipulation of starch thermal properties will be facilitated by a better understanding of the genetic control of starch gelatinization. We used differential scanning calorimetry to characterize the gelatinization parameters of maize kernel starch prepared from two populations of recombinant inbred lines, an intermated B73xMo17 population (IBM) and an F6:7 Mo17xH99 population. The traits examined were the onset and peak temperatures of gelatinization and the enthalpy of gelatinization of both native starch and also of gelatinized starch allowed to recrystallize by storage at 4oC for one week, a process called retrogradation. Substantial variation for these traits was found in spite of the narrow genetic base of the populations. We identified several quantitative trait loci controlling traits of interest in both populations. Up to 26% of the variation for a trait could be explained by a significant quantitative trait locus. The Wx1 gene, encoding a granule bound starch synthase co-localized to a significant quantitative trait locus for the percentage of starch undergoing retrogradation. This study underscores the complexity of the genetic control of starch functional properties.