Retention of thermal properties in starches from a chemically mutagenized corn inbred over three inbreeding cycles

Abstract

Chemically mutagenized corn lines were previously identified for having starches with unique functional properties measured by differential scanning calorimetry (DSC). The objective of this study was to investigate whether starches from these chemically mutagenized corn lines retained their unusual thermal properties during the additional inbreeding cycles. The mutagenized lines from a common inbred, B73, were self-pollinated and grown for three growing seasons. From each line, gelatinization and retrogradation properties of starch from single kernels were evaluated by DSC. After successive growing years, differences in gelatinization properties of the selected samples narrowed, shown by decreased ranges of values within a year for many of the gelatinization parameters. In addition, gelatinization peaks in subsequent years tended to yield slimmer and taller peaks, suggesting increased homogeneity of the starch granules. Greater onset temperatures and smaller range of gelatinization may have resulted from environmental influences. Over time, starch in the different lines may have increased in homogeneity, which could explain the decrease in ranges of values among thermal properties. These results suggest that when unique properties are identified in a new corn type, regrowing the corn for several years under similar growing conditions is necessary to establish the presence of fixed traits.