Variation in the Chain‐length Distribution Profiles of Endosperm Starch from Triticum and Aegilops Species

Abstract

AbstractThe 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.