Development and characterization of corn lines with new starch properties

Abstract

<p>The objectives of this research were to evaluate functions and structures of starches from exotic x adapted inbred lines and exotic breeding crosses (exotic populations x adapted lines), and to establish relationships between the fine structure and functional properties of the starches. A secondary objective was to confirm the advancement of selected functional traits into the next generation of corn.;A small-scale corn-starch extraction procedure optimized in this research was used to extract starch from corn kernels. Starches from several developmental lines with unusual thermal properties as measured on a Differential Scanning Calorimeter (DSC, gelatinization onset temperature (ToG) < 60°C or range of gelatinization (RG) > 14°C) were selected for further characterization. Two independent gelatinization transitions, located in different starch granules, were found in some starches. All selected starches from the developmental lines had greater peak viscosity as measured on a Rapid Visco Analyser (RVA) than did starch from normal corn inbreds Mo17. Significant differences were observed in starch-granule size distributions and shape distributions of the selected starches. Measurements with high-performance anion-exchange chromatography (HPAEC) revealed that all selected high-performance anion-exchange chromatography (HPAEC) revealed that all selected unusual starches had a lower normalized concentration of chains with a degree of polymerization (dp) of 15--24 and/or a greater normalized concentration of chains with dp of 6--12. To study the effect of environment and genotype on the gelatinization properties of starches from developmental corn lines, starches from developmental corn lines, grown (1) during three successive generations; and (2) in both temperate and tropical environments, were evaluated. Unusual thermal properties (low ToG) were fixed in some progeny lines. Environmental factors had a significant effect on the thermal properties of starch, and a significant interaction between environment and genotype was observed. These results suggest that incorporation of exotic alleles into Corn Belt germplasm is an excellent means to obtain value-added traits to produce starch with desirable functions.</p>