Variation in the Chain-length Distribution Profiles of Endosperm Starch fromTriticum andAegilops Species

The baseline variation data on the chain-length distribution profiles of endosperm starch were acquired for use as a criterion for variation among bread wheat (Triticum aestivum L.) cultivars/lines. A total of 126 starch samples isolated from closely related species belonging to the Triticum-Aegilops group, i.e., five Triticum and 22 Aegilops species, were examined. Their side-chains were debranched by isoamylase and chain-length distribution profiles were determined by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). An averaged chain-length distribution profile calculated from all data indicated that the most abundant side-chain had a degree of polymerization (DP) of 11 and its proportion based on relative peak area was 7.5%. The side-chains were classified into four groups, and the average proportions of each group were as follows; DP 6-12, 28.5% (range 26.3-30.9%); DP 13-24, 48.6% (46.2-50.8%); DP 25-36, 13.7% (12.8-15.2%) and DP ≥37, 8.9% (7.2-10.6%). The chain-length distribution profiles of Triticum and Aegilops species were essentially similar and no peculiar profile was observed. The range of the variation in the proportion of side-chain groups, however, was comparable to the difference between waxy and non-waxy bread wheat starches and among starches from wheat grown at different temperatures; this would affect the gelatinization and retrogradation properties of starch.