DOI: 10.1094/CC-82-0546 |  VIEW ARTICLE

Identification of QTL Controlling Thermal Properties of Maize Starch.

M. P. Scott (1,2) and S. A. Duvick (3). (1) USDA-ARS, Corn Insects and Crop Genetics Research Unit, Ames, IA 50011. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. (2) Corresponding author. Phone: 515-294-7825. Fax: 515-294-9359. E-mail: <pscott@iastate.edu> (3) USDA-ARS North Central Region Plant Introduction Station, Ames, IA 50011. Cereal Chem. 82(5):546-553. Accepted May 31, 2005. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. AACC International, Inc., 2005.

Starch has many uses and some of these uses would be facilitated by altering its thermal properties. 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 (Zea mays L.) kernel starch prepared from two populations of recombinant inbred lines, an intermated B73xMo17 population (IBM) and an F(6:7) Mo17xH99 population. The traits examined were the onset and peak temperatures of gelatinization and the enthalpy of gelatinization. These traits were measured for both native starch and for gelatinized starch allowed to recrystallize, a process called retrogradation. Substantial variation in these traits was found in spite of the narrow genetic base of the populations. We identified several quantitative trait loci (QTL) controlling traits of interest in each population. In the IBM population, a significant QTL for the peak temperature of gelatinization of retrograded starch co-localized to a molecular marker in the Wx1 gene, which encodes a granule bound starch synthase. The major QTL identified in this study explain, on average, approximately 15% of the variation for a given trait, underscoring the complexity of the genetic control of starch functional properties.