Physicochemical Characteristics of Starches of Two Sets of Near‐isogenic Wheat Lines with Different Amylose Content

Abstract

AbstractWheat lines with modified amylose content were produced by controlling the null alleles of three homoeologous Wx loci, Wx‐A1, Wx‐B1 and Wx‐D1 and those with triple‐null Wx alleles were found to yield waxy, amylose‐free starch. In this study, the new near‐isogenic lines developed by the recurrent backcross method between cv. Kanto 107 and the waxy mutant lines, K107Wx1 or K107Wx2, were cultivated and the physicochemical characteristics of their starches were investigated. The apparent amylose contents of the waxy near‐isogenic lines were 1.6 – 3.8%, whereas those of the non‐waxy near‐isogenic lines were 23.2 – 25.4%. The waxy lines had higher gelatinization temperature and enthalpy than the non‐waxy lines and no peak of amylose‐lipid complex as determined by DSC. The X‐ray diffraction patterns from both waxy and non‐waxy near‐isogenic lines corresponded to A‐type crystallization, like their parent lines. The starches isolated from the waxy lines had lower pasting onset and peak temperatures, higher peak viscosities and breakdown and lower final viscosity than those of the non‐waxy lines in the Viscoamylograph. The starch of non‐waxy near‐isogenic lines had lower peak and final viscosities and higher breakdown than did the recurrent parent line, cv. Kanto 107. The characteristics of the new wheat starches were well understood and classified, which will contribute to the wide application of these starches in food processing.