DSC CHARACTERISTICS OF GELATINIZATION OF STARCHES OF SINGLE-MUTANTS, DOUBLE-MUTANTS, AND TRIPLE-MUTANTS AND THEIR NORMAL COUNTERPART IN THE INBRED OH43-MAIZE (ZEA-MAYS L) BACKGROUND

Starch granules were isolated from mature kernels of single-, double-, and triple-mutants of endosperm starch modifying genes [waxy(wx), dull(du), amylose extender(ae), sugary-2(su2)] and their normal counterpart in the inbred Oh43 maize (Zea mays L.) background. Gelatinization characteristics of the starch granules were investigated by means of differential scanning calorimetry (DSC). The onset, peak, and conclusion temperatures of gelatinization (To, Tp, and Tc, respectively) and the heat of gelatinization (DELTA-H) of starch were determined from the DSC thermograms, The Tc of wx was higher than normal starch, and the DELTA-H of wx was larger than normal starch. The Tp and Tc values of ae starch were the highest. The To, Tp, and Tc values of su2 starch were low. The noticeable effects of each of the wx, ae, and su2 genes on To, Tp, Tc and DELTA-H were observed in starches of their respective mutant combinations. Apparent epistatic effects of the genes for gelatinization temperature were observed. Pronounced effect of the heating rate on gelatinization temperature of su2 containing starches was observed. The DELTA-H values ot starches containing the su2 mutant were lower than other mutant starches and were affected by the heating rate.